®

RT8230A/B/C/D/E

Dual-Channel Synchronous DC/DC Step-Down Controller

with 5V/3.3V LDOs
General Description Features
The RT8230A/B/C/D/E is a dual-channel step-down,  Maximum Duty Up to 96%
controller generating supply voltages for battery-powered  CCRCOT Control with 100ns Load Step Response
systems. It includes two Pulse-Width Modulation (PWM)  Wide Input Voltage Range : 5V to 25V
controllers adjustable from 2V to 5.5V, and two fixed 5V/  Dual Adjustable Output :
3.3V linear regulators. Each linear regulator provides up  CH1 : 2V to 5.5V

to 100mA output current. The 5V linear regulator supplies  CH2 : 2V to 4V

power to the PWM drivers. The RT8230A/B/C/D/E includes  Fixed 3.3V and 5V LDO Output : 100mA
on-board power-up sequencing, a power-good output,  1% Accuracy on 3.3V LDO Output
internal soft-start, and soft-discharge output that prevents  Frequency Adjustable Via TON Setting
negative voltage during shutdown.  4700ppm/ °C RDS(ON) Current Sensing
 Adjustable Current Limit Combined with Enable
A constant current ripple PWM control scheme operates
Control
without sense resistors and provides 100ns response to
 Internal Soft-Start and Soft-Discharge
load transient. To eliminate noise in audio applications,
 Thermal Shutdown
an ultrasonic mode is included, which maintains the
 RoHS Compliant and Halogen Free
switching frequency above 25kHz. Moreover, the diode-
emulation mode maximizes efficiency for light load
applications. The RT8230A/B/C/D/E is available in the
Applications
WQFN-20L 3x3 package.  Notebook and Sub-Notebook Computers
 2-Cell, 3-Cell and 4-Cell Li+ Battery-Powered Devices

Simplified Application Circuit

VIN

RT8230A/B/C/D/E

VIN VIN
UGATE2

BOOT2 *
ENLDO/ENC ENLDO/ENC
VIN
PHASE2 VOUT2
LGATE2
UGATE1
* BOOT1 FB2

VOUT1 PHASE1 ENTRIP2

LGATE1
ENTRIP1

FB1
RTON LDO3 3.3V
TON

BYP1 LDO5 5V

ENM/SECFB ENM/SECFB

GND PGOOD PGOOD

* : optional

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RT8230A/B/C/D/E
Ordering Information Pin Configurations
RT8230A/B/C/D/E
(TOP VIEW)

UGATE1
Package Type

PHASE1
LGATE1
BOOT1
BYP1
QW : WQFN-20L 3x3 (W-Type)
Lead Plating System
20 19 18 17 16
G : Green
FB1 1 15 LDO3
(Halogen Free and Pb Free) ENTRIP1 2 14 LDO5
TON 3 GND 13 ENM
Pin Function With
ENTRIP2 4 21 12 ENLDO
A : ENM+ENLDO FB2 5 11 VIN
B/D : SECFB+ENLDO 6 7 8 9 10
C/E : SECFB+ENC

BOOT2
UGATE2

LGATE2
PGOOD

PHASE2
Note :
Richtek products are :
 RoHS compliant and compatible with the current require- RT8230A
ments of IPC/JEDEC J-STD-020.

UGATE1
PHASE1
LGATE1
BOOT1
 Suitable for use in SnPb or Pb-free soldering processes.

BYP1
20 19 18 17 16
Marking Information FB1 1 15 LDO3
RT8230AGQW ENTRIP1 2 14 LDO5
TON 3 GND 13 SECFB
2F= : Product Code
ENTRIP2 4 21 12 ENLDO
2F=YM YMDNN : Date Code FB2 5 11 VIN
DNN 6 7 8 9 10

BOOT2
UGATE2

LGATE2
PGOOD

PHASE2
RT8230BGQW
2E= : Product Code RT8230B/D
2E=YM YMDNN : Date Code
UGATE1
PHASE1
LGATE1
BOOT1

DNN
BYP1

20 19 18 17 16
RT8230CGQW FB1 1 15 LDO3
2D= : Product Code ENTRIP1 2 14 LDO5
TON 3 GND 13 SECFB
2D=YM YMDNN : Date Code
ENTRIP2 4 21 12 ENC
DNN FB2 5 11 VIN
6 7 8 9 10
BOOT2
UGATE2

LGATE2
PGOOD

PHASE2

RT8230DGQW
3C= : Product Code
3C=YM YMDNN : Date Code RT8230C/E
DNN
WQFN-20L 3x3

RT8230EGQW
3D= : Product Code
3D=YM YMDNN : Date Code
DNN

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 RT8230A/B/C/D/E
Functional Pin Description
Pin No. Pin Name Pin Function
Feedback Voltage Input for Channel 1. Connect FB1 to a resistive voltage
1 FB1
divider from VOUT1 to GND to adjust output from 2V to 5.5V.
Enable and Current Limit Setting for Channel 1. There is an internal 5A
current source to the ENTRIP1 pin. Connect a resistor to GND to set the
2 ENTRIP1
threshold between 0.2V and 3V for channel 1 current limit. The GND 
PHASE1 current limit threshold is 1/10th the voltage on the ENTRIP1 pin.
Switching Frequency Setting. Connect a resistor to GND to adjust switching
3 TON
frequency.
Enable and Current Limit Setting for Channel 2. There is an internal 5A
current source to the ENTRIP2 pin. Connect a resistor to GND to set the
4 ENTRIP2
threshold between 0.2V and 3V for channel 2 current limit. The GND 
PHASE2 current limit threshold is 1/10th the voltage on the ENTRIP2 pin.
Feedback Voltage Input for Channel 2. Connect FB2 to a resistive
5 FB2
voltage-divider from VOUT2 to GND to adjust output from 2V to 4V.
6 PGOOD Power Good Output for Channel 1 and Channel 2. (Logical AND)
Bootstrap Supply for Channel 2 High-Side Gate Driver. Connect to an external
7 BOOT2
capacitor according to the typical application circuits.
8 UGATE2 Gate Drive Output for Channel 2 High-Side MOSFET.
Switch Node of Channel 2 MOSFETs. PHASE2 is the return rail for the
9 PHASE2
UGATE2 high-Side gate driver.
LGATE2
Gate Drive Output for Channel 2 Low-Side MOSFET.
(RT8230A/B/E)
10 Gate Drive Output for Channel 2 Low-Side MOSFET and Charge Pump CLK.
LGATE2
The CLK frequency will become fast to pull up charge pump voltage when the
(RT8230C/D)
SECFB voltage is low to 2V.
11 VIN Supply Voltage Input.
ENLDO Master Enable Control Input. The LDO5/LDO3 are enabled if it is within logic
(RT8230A/B/D) high level and disable if it is less than the logic low level.
12
ENC Master Enable Control Input. The channels are enabled if it is within logic high
(RT8230C/E) level and disable if it is less than the logic low level.
ENM Mode Selection with Enable Control Input. Pull up to LDO5 (Ultrasonic mode)
(RT8230A) or LDO3 (DEM) to turn on both switch channels. Short to GND for shutdown.
13 Feedback Voltage Input for Charge Pump. The SECFB is used to monitor the
SECFB
optional external 14V charge pump. Connect a resistive voltage divider from
(RT8230B/C/D/E)
14V charge pump output to GND to detect the output.
5V Linear Regulator Output. It is also the supply voltage for the low-side
14 LDO5
MOSFET driver and analog supply control circuits.
15 LDO3 3.3V Linear Regulator Output.
LGATE1
Gate Drive Output for Channel 1 Low-Side MOSFET.
(RT8230A/C/D)
16 Gate Drive Output for Channel 1 Low-Side MOSFET and Charge Pump CLK.
LGATE1
The CLK frequency will become fast to pull up charge pump voltage when the
(RT8230B/E)
SECFB voltage is low to 2V.

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RT8230A/B/C/D/E
Pin No. Pin Name Pin Function
Switch Node of Channel 1 MOSFETs. PHASE1 is the return rail for the
17 PHASE1
UGATE1 high-Side gate driver.
18 UGATE1 Gate Drive Output for Channel 1 High-Side MOSFET.
Bootstrap Supply for Channel 1 High-Side Gate Driver. Connect to an external
19 BOOT1
capacitor according to the typical application circuits.
20 BYP1 Switch Over Source Voltage Input for LDO5.
21 Ground. The exposed pad must be soldered to a large PCB and connected to
GND
(Exposed Pad) GND for maximum power dissipation.

Function Block Diagram

TON

BOOT1 BOOT2

UGATE1 UGATE2

PHASE1 PHASE2
LDO5 LDO5
Channel1 Channel2
Buck Buck
LGATE1 Controller Controller LGATE2

FB1 FB2
ENTRIP1 ENTRIP2
SW5 PGOOD
Threshold
BYP1
GND
Power-On
Sequence ENLDO/ENC
Clear Fault Latch ENM/SECFB

LDO5

LDO5 REF LDO3 LDO3

VIN BYP1

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 RT8230A/B/C/D/E
Operation
The RT8230A/B/C/D/E includes two constant on-time Over-Voltage Protection (OVP) & Under-Voltage
synchronous step-down controllers and two linear Protection (UVP)
regulators. The two channel output voltages are continuously
monitored for over-voltage and under-voltage conditions.
Buck Controller
When the output voltage exceeds OVP threshold (113%
In normal operation, the high-side N-MOSFET is turned of VOUT), UGATE goes low and LGATE is forced high;
on when the output is lower than VREF, and is turned off when it is less than 52% of reference voltage, under-
after the internal one-shot timer expires. While the high- voltage protection is triggered and then both UGATE and
side N-MOSFET is turned off, the low-side N-MOSFET is LGATE gate drivers are forced low. The controller is latched
turned on to conduct the inductor current until next cycle until ENTRIP is reset or LDO5 is re-supplied.
begins.
LDO5 and LDO3
Soft-Start (SS)
When the VIN voltage exceed the POR rising threshold,
For internal soft-start function, an internal current source the LDO5 and LDO3 can be power on by ENLDO.
charges an internal capacitor to build the soft-start ramp
The linear regulator LDO5 and LDO3 provide 5V and 3.3V
voltage. The output voltage will track the internal ramp
regulated output.
voltage during soft-start interval.
Switching Over
PGOOD
The BYP1 is connected to the channel 1 output. After the
The power good output is an open-drain architecture.
channel 1 output voltage exceeds the set threshold
When the two channels soft-start are both finished, the
(4.66V), the output will be bypassed to the LDO5 output
PGOOD open-drain output will be high impedance.
to maximize the efficiency.
Current Limit
The current limit circuit employs a unique “valley” current
sensing algorithm. If the magnitude of the current sense
signal at PHASE is above the current limit threshold, the
PWM is not allowed to initiate a new cycle. Thus, the
current to the load exceeds the average output inductor
current, the output voltage falls and eventually crosses
the under-voltage protection threshold, inducing IC
shutdown.

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RT8230A/B/C/D/E
Absolute Maximum Ratings (Note 1)
 VIN, ENLDO, ENC to GND ------------------------------------------------------------------------------------- −0.3V to 30V
 BOOTx to PHASEx ---------------------------------------------------------------------------------------------- −0.3V to 6V
 PHASEx to GND
DC -------------------------------------------------------------------------------------------------------------------- −0.3V to 30V
<20ns --------------------------------------------------------------------------------------------------------------- −8V to 38V
 UGATEx to PHASEx
DC -------------------------------------------------------------------------------------------------------------------- −0.3V to (LDO5 + 0.3V)
<20ns --------------------------------------------------------------------------------------------------------------- −5V to 7.5V
 LGATEx to GND
DC -------------------------------------------------------------------------------------------------------------------- −0.3V to (LDO5 + 0.3V)
<20ns --------------------------------------------------------------------------------------------------------------- −2.5V to 7.5V
 Other Pins ---------------------------------------------------------------------------------------------------------- −0.3V to 6V
 Power Dissipation, PD @ TA = 25°C
WQFN-20L 3x3 --------------------------------------------------------------------------------------------------- 3.33W
 Package Thermal Resistance (Note 2)
WQFN-20L 3x3, θJA ---------------------------------------------------------------------------------------------- 30°C/W
WQFN-20L 3x3, θJC --------------------------------------------------------------------------------------------- 7.5°C/W
 Junction Temperature -------------------------------------------------------------------------------------------- 150°C
 Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------- 260°C
 Storage Temperature Range ----------------------------------------------------------------------------------- −65°C to 150°C
 ESD Susceptibility (Note 3)
HBM (Human Body Model) ------------------------------------------------------------------------------------- 2kV

Recommended Operating Conditions (Note 4)

 Supply Voltage, VIN --------------------------------------------------------------------------------------------- 5V to 25V
 Junction Temperature Range ----------------------------------------------------------------------------------- −40°C to 125°C
 Ambient Temperature Range ----------------------------------------------------------------------------------- −40°C to 85°C

Electrical Characteristics
(VIN = 12V, VENLDO = VENC = 5V, VENTRIP1 = VENTRIP2 = 2V, No load, TA = 25°C, unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
Input Supply
Rising Threshold -- 4.6 5
VIN Power On Reset PORVIN V
Falling Threshold 3.2 3.7 --
VIN Shutdown Supply Current IVIN_SHDN VENLDO = GND -- 10 25 A
Not Switching, VENLDO = 5V,
VIN Standby Supply Current IVIN_SBY -- 50 80 A
VENM = GND
BYP1 Quiescent Current IQ_nosw VFBx = 2.05V -- 150 200 A
Buck Output and FB Voltage
FBx Valley Trip Voltage VFBx CCM Operation 1.98 2 2.02 V
SECFB Voltage VSECFB 1.92 2 2.08 V
PHASEx Discharge Current IDCHGx VPHASEx = 0.5V 5 8 -- mA

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 RT8230A/B/C/D/E
Parameter Symbol Test Conditions Min Typ Max Unit
Frequency Control
VIN = 20V, VOUT1 = 5V, RTON = 100k 240 300 360
Switching Frequency f SWx kHz
VIN = 20V, VOUT2 = 3.33V, RTON = 100k 280 355 430
Minimum Off-Time T LGATEx VFBX = 1.9V -- 275 350 ns
Ultrasonic Mode Frequency f ASM VENM = LDO5 25 33 -- kHz
Soft-Start
Soft-Start Time TSSX From ENTRIP Enable -- 0.8 -- ms
Current Sense
ENTRIPx Source Current IENTRIPx VENTRIPx = 0.9V 4.5 5 5.5 A
ENTRIPx Current
TCIENTRIPx In Comparison with 25C -- 4700 -- ppm/C
Temperature Coefficient
Zero-Current Threshold VZC VFBx = 2.05V, GND  PHASEx -- 1 -- mV
Internal Regulator
VIN = 12V, No Load 4.9 5 5.1
VIN > 7V, ILDO5 < 100mA 4.8 5 5.1
LDO5 Output Voltage VLDO5 V
VIN > 5.5V, ILDO5 < 35mA 4.8 5 5.1
VIN > 5V, ILDO5 < 20mA 4.5 4.75 5.1
VIN = 12V, No Load 3.267 3.3 3.333
VIN > 7V, ILDO3 < 100mA 3.217 3.3 3.383
LDO3 Output Voltage VLDO3 V
VIN > 5.5V, ILDO3 < 35mA 3.267 3.3 3.333
VIN > 5V, ILDO3 < 20mA 3.217 3.3 3.383
LDO5 Output Current ILDO5 VLDO5 = 4.5V, VBYP1 = GND, VIN = 7.4V 100 175 -- mA
LDO3 Output Current ILDO3 VLDO3 = 3V, VIN = 7.4V 100 175 -- mA
LDO5 Switchover Threshold
VSWTH Rising Edge At BYP1 Regulation Point 4.4 4.66 4.79 V
to BYP1
LDO5 Switchover Equivalent
RSW LDO5 to BYP1, 10mA -- 1.5 3 
Resistance
UVLO
Rising Edge -- 4.3 4.5
LDO5 UVLO Threshold VUVLO5
Falling Edge 3.7 3.9 4.1 V
LDO3 UVLO Threshold VUVLO3 Controllers Off -- 2.5 --
Power Good
PGOOD Detect, VFBx Rising Edge 87 92.5 96
PGOOD Threshold VPGxTH %
Hysteresis -- 8 --
PGOOD Leakage Current High State, VPGOOD = 5.5V -- -- 1 A
PGOOD Output Low Voltage ISINK = 4mA -- -- 0.3 V
Fault Detection
OVP Trip Threshold VOVP FBx with Respect to Internal Reference 109 113 117 %
OVP Propagation Delay -- 1 -- s
UVP Trip Threshold VUVP UVP Detect, FBx Falling Edge 47 52 57 %
UVP Shutdown Blanking
tSHDN_UVP From ENTRIPx Enable -- 1.6 -- ms
Time

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RT8230A/B/C/D/E
Parameter Symbol Test Conditions Min Typ Max Unit
Thermal Shutdown
Thermal Shutdown T SHDN -- 150 -- C
Thermal Shutdown
-- 10 -- C
Hysteresis
Logic Inputs
Controller On 0.2 -- 3
ENTRIPx Input Voltage VENTRIPx V
Controller Off 4.5 -- --
Shutdown -- -- 0.4
ENLDO Input Voltage
VENLDO Enable 1 -- -- V
(RT8230A/B/D)
ENLDO Floating, Default Enable 1.6 2.4 3.3
ENLDO Current VENLDO = 0.2V, Source -- 1 5
I ENLDO A
(RT8230A/B/D) VENLDO = 5V, Sink -- 1 5
Shutdown -- -- 0.4
ENC Input Voltage
VENC Enable 1 -- -- V
(RT8230C/E)
ENC Floating, Default Enable 1.6 2.4 3.3
Buck Controller Off Level -- -- 0.8
Buck Controller On Level, ASM Operation
ENM Input Voltage 1.2 -- 1.8
(only for CH1, CH2 keep on DEM)
(RT8230A) V
VENM Buck Controller On Level, DEM Operation 2.3 -- 3.6
Buck Controller On Level, ASM Operation 4.5 -- --
Buck Controller On Level, ASM Operation
1.2 -- 1.8
(RT8230B/E for CH1, RT8230C/D for CH2)
SECFB Input Voltage
VSECFB V
(RT8230B/C/D/E) Buck Controller On Level, DEM Operation 2.3 -- 3.6
Buck Controller On Level, ASM Operation 4.5 -- --
Internal Boost Switch
Internal Boost Switch
LDO5 to BOOTx -- 80 -- 
On-Resistance
Power MOSFET Drivers
High State, VBOOTx  VUGATEx = 0.25V,
-- 3 --
VBOOTx  VPHASEx = 5V
UGATEx On-Resistance 
Low State, VUGATEx  VPHASEx = 0.25V,
-- 2 --
VBOOTx  VPHASEx = 5V
High State, VLDO5  VLGATEx = 0.25V,
-- 3 --
LGATEx On-Resistance VLDO5 = 5V 
Low State, VLGATEx  GND = 0.25V -- 1 --
LGATEx Rising -- 20 --
Dead-Time ns
UGATEx Rising -- 30 --

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 RT8230A/B/C/D/E
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. Not production tested. Test condition is same with electrical characteristics using application circuit.

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RT8230A/B/C/D/E
Typical Application Circuit
VIN
5V to 25V
C1 R1 RT8230A C5
10µF 10µF
11 VIN UGATE2 8 N3
C2
0.1µF 12 ENLDO 7 R5*
BOOT2
18 UGATE1 C6 L2
N1
0.1µF 3.3µH
VOUT2
R2* 19
BOOT1 PHASE2 9

+
3.3V
C4 10
L1 LGATE2 N4 C7
VOUT1 3.3µH 0.1µF
17 PHASE1 R6
5V 66.5k
+

16
C3 N2 LGATE1 FB2 5
R3 R7
150k R8
ENTRIP2 4 100k
1
FB1
R9
R4 RTON 3 TON ENTRIP1 2
100k

20 BYP1 LDO3 15 3.3V

C8
C14 4.7µF
1µF 13 ENM
Enable
LDO5 14 5V
C9
21 (Exposed Pad) 4.7µF
GND
* : optional PGOOD 6 PGOOD

VIN
5V to 25V
C1 R1 RT8230B C5
10µF 10µF
11 VIN UGATE2 8 N3
C2
0.1µF 12 ENLDO 7 R5*
BOOT2
18 UGATE1 C6 L2
N1
0.1µF 3.3µH
R2* VOUT2
19
BOOT1 PHASE2 9
+

3.3V
L1 C4 10
LGATE2 N4 C7
3.3µH 0.1µF
VOUT1 17 PHASE1 R6
66.5k
+

5V
16
C3 N2 LGATE1 FB2 5
R3 R7
150k R8
ENTRIP2 4 100k
1
FB1
2 R9
R4 RTON 3 TON ENTRIP1
100k On

20 BYP1 Off
C14 C10
1µF 0.1µF 15
LDO3 3.3V
C12 C8
0.1µF 4.7µF
C11
0.1µF LDO5 14 5V
C9
4.7µF

C13
R10 PGOOD 6 PGOOD
200k 13
1µF SECFB 21 (Exposed Pad)
R11 GND
39k
VCP
* : optional

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 RT8230A/B/C/D/E
VIN
5V to 25V
C1 R1 RT8230C C5
10µF 10µF
11
VIN UGATE2 8 N3
C2
0.1µF 12 ENC 7 R5*
BOOT2
18 UGATE1 C6
N1 L2
0.1µF 3.3µH
R2* 19 9 VOUT2
BOOT1 PHASE2

+
3.3V
L1 C4 LGATE2 10 N4 C7
3.3µH 0.1µF R6
VOUT1 17 PHASE1 66.5k
5V
+

16 FB2 5
C3 N2 LGATE1
R7
R3
100k
150k
1 C10
FB1 0.1µF
R4 RTON
100k 3 TON C12
0.1µF
C11
20 0.1µF
BYP1
C14
1µF 6
PGOOD PGOOD
R10
13 200k C13
15 1µF
3.3V Always On LDO3 SECFB
C8
R11
4.7µF
39k
VCP
14
5V Always On LDO5 R8
C9 4
4.7µF ENTRIP2
2 R9
21 (Exposed Pad) ENTRIP1
GND
* : optional

VIN
5V to 25V
C1 R1 RT8230D C5
10µF 8 10µF
11 VIN UGATE2 N3
C2
0.1µF 12 ENLDO 7 R5*
BOOT2
18 UGATE1 C6
N1 L2
0.1µF 3.3µH
R2* 19 9 VOUT2
BOOT1 PHASE2
+
3.3V
L1 C4 LGATE2 10 N4 C7
3.3µH 0.1µF R6
VOUT1 17 PHASE1 66.5k
5V
+

16 FB2 5
C3 N2 LGATE1
R7
R3
100k
150k
1 C10
FB1 0.1µF
R4 RTON
100k 3 TON C12
0.1µF
C11
20 0.1µF
BYP1
C14
1µF 6
PGOOD PGOOD
R10
15 13 200k C13
3.3V LDO3 SECFB 1µF
C8
R11
4.7µF
39k
VCP
14
5V LDO5 R8
C9
4.7µF ENTRIP2 4
2 R9
21 (Exposed Pad) ENTRIP1 On
GND
* : optional Off

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RT8230A/B/C/D/E
VIN
5V to 25V
C1 R1 RT8230E C5
10µF 11 VIN 8 10µF
UGATE2 N3
C2
0.1µF 12 ENC 7 R5*
BOOT2
18 UGATE1 C6
N1 L2
0.1µF 3.3µH
R2* 19 9 VOUT2
BOOT1 PHASE2

+
3.3V
L1 C4 LGATE2 10 N4 C7
3.3µH 0.1µF
VOUT1 17 PHASE1 R6
5V 66.5k
+

16
C3 N2 LGATE1 FB2 5
R3 R7
150k R8 100k
1 ENTRIP2 4
FB1
R4 RTON 2 R9
3 TON ENTRIP1
100k

20 BYP1
C14 C10 15
1µF LDO3 3.3V Always On
0.1µF C8
C12 4.7µF
0.1µF
C11 LDO5 14 5V Always On
0.1µF C9
4.7µF

R10 PGOOD 6 PGOOD

C13 200k 13
1µF SECFB
21 (Exposed Pad)
R11 GND
39k
VCP
* : optional

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 RT8230A/B/C/D/E
Typical Operating Characteristics
Efficiency vs. Load Current Efficiency vs. Load Current
100
100% 100%
100
VOUT1 VOUT1
90
90% DEM 90%
90
DEM
80
80% ASM 80%
80 ASM
70%
70 70%
70

Efficiency (%)
Efficiency(%)

60
60% 60%
60
50
50% 50%
50
40
40% 40%
40
30
30% 30
30%
20%
20 20%
20
10%
10 VIN = 7.4V, RTON = 100kΩ, ENLDO = 5V, VIN = 12V, RTON = 100kΩ, ENLDO = 5V,
10%
10
VENTRIP1 = 0.75V, VENTRIP2 = 5V VENTRIP1 = 0.75V, VENTRIP2 = 5V
0%0 0%
0
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

Efficiency vs. Load Current Efficiency vs. Load Current

100%
100 100
100%
VOUT1 VOUT2
90%
90 90
90%
DEM DEM
80%
80 80
80% ASM
ASM
70%
70 70
70%
Efficiency (%)

Efficiency(%)

60%
60 60
60%
50%
50 50
50%

40%
40 40
40%

30%
30 30
30%
20%
20 20%
20
VIN = 20V, RTON = 100kΩ, ENLDO = 5V, VIN = 7.4V, RTON = 100kΩ, ENLDO = 5V,
10%
10 10%
10
VENTRIP1 = 0.75V, VENTRIP2 = 5V VENTRIP1 = VENTRIP2 = 0.75V
0%
0 0
0%
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

Efficiency vs. Load Current Efficiency vs. Load Current

100%
100 100
100%
VOUT2 VOUT2
90%
90 90
90%
80%
80 DEM 80
80%
ASM DEM
70%
70 70%
70 ASM
Efficiency (%)

Efficiency (%)

60%
60 60%
60
50%
50 50
50%
40%
40 40
40%
30%
30 30
30%
20%
20 20%
20
10% VIN = 12V, RTON = 100kΩ, ENLDO = 5V, 10
10% VIN = 20V, RTON = 100kΩ, ENLDO = 5V,
10
VENTRIP1 = VENTRIP2 = 0.75V VENTRIP1 = VENTRIP2 = 0.75V
0%
0 0
0%
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

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Switching Frequency vs. Load Current Switching Frequency vs. Load Current
250 300
VOUT1, VIN = 8V, VOUT1, VIN = 12V,

Switching Frequency (kHz)1

RTON = 100kΩ, ENLDO = VIN, RTON = 100kΩ, ENLDO = VIN,
Switching Frequency (kHz)1

VENTRIP1 = 0.75V, VENTRIP2 = 5V 250 VENTRIP1 = 0.75V, VENTRIP2 = 5V

200 DEM
DEM ASM
ASM 200
150
150
100
100

50
50

0 0
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

Switching Frequency vs. Load Current Switching Frequency vs. Load Current
350 300
VOUT1, VIN = 20V, VOUT2, VIN = 8V,
Switching Frequency (kHz)1

Switching Frequency (kHz)1

RTON = 100kΩ, ENLDO = VIN, RTON = 100kΩ, ENLDO = VIN,

300 250 DEM
VENTRIP1 = 0.75V, VENTRIP2 = 5V DEM VENTRIP1 = 5V, VENTRIP2 = 0.75V
ASM
ASM
250
200
200
150
150
100
100

50 50

0 0
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

Switching Frequency vs. Load Current Switching Frequency vs. Load Current
350 400
VOUT2, VIN = 12V, VOUT2, VIN = 20V,
RTON = 100kΩ, ENLDO = VIN,
Switching Frequency (kHz)1

Switching Frequency (kHz)1

DEM 350 RTON = 100kΩ, ENLDO = VIN,

300 DEM
VENTRIP1 = 5V, VENTRIP2 = 0.75V ASM VENTRIP1 = 5V, VENTRIP2 = 0.75V
ASM
300
250
250
200
200
150
150
100
100

50 50

0 0
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

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 RT8230A/B/C/D/E

Output Voltage vs. Load Current Output Voltage vs. Load Current
5.05 3.36
VOUT1 VOUT2
5.04
DEM DEM
5.03 3.35
Output Voltage (V)

Output Voltage (V)

5.02
5.01 ASM 3.34
5.00
4.99 3.33 ASM
4.98
4.97 3.32
4.96 VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VIN = 12V, RTON = 100kΩ, ENLDO = VIN,
VENTRIP1 = 0.75V, VENTRIP2 = 5V VENTRIP1 = 5V, VENTRIP2 = 0.75V
4.95 3.31
0.001 0.01 0.1 1 10 0.001 0.01 0.1 1 10
Load Current (A) Load Current (A)

LDO5 Output Voltage vs. Load Current LDO3 Output Voltage vs. Load Current
5.05 3.343
5.04
3.332
5.03
Output Voltage (V)
Output Voltage (V)

5.02
3.321
5.01
5.00 3.310
4.99
3.299
4.98
4.97
3.288
4.96
VIN = 12V, ENLDO = VIN, VENTRIP1 = VENTRIP2 = 5V VIN = 12V, ENLDO = VIN, VENTRIP1 = VENTRIP2 = 5V
4.95 3.277
0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
Load Current (mA) Load Current (mA)

Quiescent Current vs. Input Voltage Standby Input Current vs. Input Voltage
10000 60
Standby Input Current (µA)1

ASM
55
Quiescent Current (µA)

1000
50
DEM
100 45

40
10
35
RTON = 100kΩ, ENLDO = VIN, ENLDO = VIN, VENTRIP1 = VENTRIP2 = 5V,
VENTRIP1 = VENTRIP2 = 0.75V, No Load No Load, Not Switching
1 30
5 7 9 11 13 15 17 19 21 23 25 5 7 9 11 13 15 17 19 21 23 25
Input Voltage (V) Input Voltage (V)

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RT8230A/B/C/D/E

Shutdown Input Current vs. Input Voltage Power On from ENLDO

25
Shutdown Input Current (µA)1

20 LDO5
(5V/Div)
15
LDO3
(2V/Div)
10 CP
(10V/Div)
5
ENLDO = GND, ENLDO VIN = 12V, RTON = 100kΩ, ENLDO = VIN,
VENTRIP1 = VENTRIP2 = 5V, No Load (10V/Div) VENTRIP1 = VENTRIP2 = 0.75V, No Load
0
5 7 9 11 13 15 17 19 21 23 25 Time (2ms/Div)
Input Voltage (V)

Power On from ENM Power Off from ENM

VIN = 12V, VENM = 5V VIN = 12V, VENM = 5V,
RTON = 100kΩ, ENLDO = VIN
VOUT1 VOUT1
(5V/Div) (5V/Div)

VOUT2 VOUT2
(2V/Div) (2V/Div)

PGOOD PGOOD
(5V/Div) (5V/Div)
ENM RTON = 100kW, ENLDO = VIN, ENM
(5V/Div) VENTRIP1 = VENTRIP2 = 0.75V, No Load (5V/Div) VENTRIP1 = VENTRIP2 = 0.75V, No Load

Time (1ms/Div) Time (10ms/Div)

Power On from ENTRIP1 Power Off from ENTRIP1

VOUT1 VOUT1
(5V/Div) (5V/Div)

PGOOD PGOOD
(5V/Div) (5V/Div)

ENTRIP1 ENTRIP1
(5V/Div) (5V/Div)
VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VIN = 12V, RTON = 100kΩ, ENLDO = VIN,
VENTRIP1 = VENTRIP2 = 0.75V, No Load VENTRIP1 = VENTRIP2 = 0.75V, No Load

Time (1ms/Div) Time (20ms/Div)

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 RT8230A/B/C/D/E

Power On from ENTRIP2 Power Off from ENTRIP2

VOUT2 VOUT2
(5V/Div) (5V/Div)

PGOOD PGOOD
(5V/Div) (5V/Div)

ENTRIP2 ENTRIP2
(5V/Div) (5V/Div)
VIN = 12V, RTON = 100kΩ, ENLDO = VIN, VIN = 12V, RTON = 100kΩ, ENLDO = VIN,
VENTRIP1 = VENTRIP2 = 0.75V, No Load VENTRIP1 = VENTRIP2 = 0.75V, No Load

Time (1ms/Div) Time (20ms/Div)

VOUT1 DEM-MODE Load Transient Response VOUT2 DEM-MODE Load Transient Response
VIN = 12V, RTON = 100kΩ VIN = 12V, RTON = 100kΩ

VOUT1_AC VOUT2_AC
(100mV/Div) (100mV/Div)

UGATE1 UGATE1
(20V/Div) (20V/Div)

IL1 IL2
(10A/Div) ENLDO = VIN, IOUT1 = 1A to 6A (10A/Div) ENLDO = VIN, IOUT2 = 1A to 6A

Time (20μs/Div) Time (20μs/Div)

OVP UVP

VOUT1 VOUT1
(2V/Div) (5V/Div)

PGOOD PGOOD
(5V/Div) (5V/Div)

UGATE1
(20V/Div)
VOUT2 LGATE1
(2V/Div) VIN = 12V, RTON = 100kΩ, ENLDO = VIN, No Load (10V/Div) VIN = 12V, RTON = 100kΩ, ENLDO = VIN

Time (10ms/Div) Time (100μs/Div)

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RT8230A/B/C/D/E
Application Information
The RT8230A/B/C/D/E is a dual-channel, low quiescent, on-time is inversely proportional to the input voltage as
Mach Response TM DRVTM mode synchronous Buck measured by VIN and proportional to the output voltage.
controller targeted for Ultrabook system power supply The inductor ripple current operating point remains
solutions. Richtek's Mach Response TM technology relatively constant, resulting in easy design methodology
provides fast response to load steps. The topology solves and predictable output voltage ripple. The frequency of 3V
the poor load transient response timing problems of fixed output controller is set higher than the frequency of 5V
frequency current mode PWMs, and avoids the problems output controller. This is done to prevent audio frequency
caused by widely varying switching frequencies in CCR “ beating” between the two sides, which switch
(constant current ripple) constant on-time and constant asynchronously for each side. The TON pin is connected
off-time PWM schemes. A special adaptive on-time control to GND through the external resistor RTON to set the
trades off the performance and efficiency over wide input switching frequency.
voltage range. The RT8230A/B/C/D/E includes 5V (LDO5) The RT8230A/B/C/D/E adaptively changes the operation
and 3.3V (LDO3) linear regulators. The LDO5 linear frequency according to the input voltage. Higher input
regulator steps down the battery voltage to supply both voltage usually comes from an external adapter, so the
internal circuitry and gate drivers. The synchronous switch RT8230A/B/C/D/E operates with higher frequency to have
gate drivers are directly powered by LDO5. When VOUT1 better performance. Lower input voltage usually comes
rises above 4.66V, an automatic circuit disconnects the from a battery, so the RT8230A/B/C/D/E operates with
linear regulator and allows the device to be powered by lower switching frequency for lower switching losses. For
VOUT1 via the BYP1 pin. a specific input voltage range, the switching cycle period
is given by :
PWM Operation
For 5V VOUT,
The Mach ResponseTM DRVTM mode controller relies on
VIN  (3.23  RTON + 3.4  104 )
the output filter capacitor's Effective Series Resistance Period (sec.) =  10-11
(ESR) to act as a current sense resistor, so that the output 1.36  VIN  5.16
ripple voltage provides the PWM ramp signal. Referring to For 3.3V VOUT,
the RT8230A/B/C/D/E's Function Block Diagram, the VIN  (2.94  RTON + 3.4  104 )
Period (sec.) =  10-11
synchronous high-side MOSFET is turned on at the 1.36  VIN +1.46  10-5  RTON  5.3
beginning of each cycle. After the internal one-shot timer
where the VIN is in volt, RTON is in ohm.
expires, the MOSFET will be turned off. The pulse width
of this one-shot is determined by the converter's input The on-time guaranteed in the Electrical Characteristics
output voltages to keep the frequency fairly constant over table is influenced by switching delays in the external
the entire input voltage range. Another one-shot sets a high-side power MOSFET.
minimum off-time (275ns typ.). The on-time one-shot will
Operation Mode Selection
be triggered if the error comparator is high, the low-side
The RT8230A/B/C/D/E supports two operation modes :
switch current is below the current limit threshold, and
diode emulation mode and ultrasonic mode. The operation
the minimum off-time one-shot has timed out.
mode can be set via the ENM pin for the RT8230A or the
PWM Frequency and On-time Control SECFB pin for the RT8230B/C/D/E.
For each specific input voltage range, the Mach
ResponseTM control architecture runs with pseudo constant
frequency by feed forwarding the input and output voltage
into the on-time one-shot timer. The high-side switch

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 RT8230A/B/C/D/E
Table 1. Operation Mode Setting
Part Number RT8230A RT8230B/E RT8230C/D
Pin Name ENM SECFB SECFB
Pin-13 Voltage Range Mode State
4.5V to 5V ASM ASM ASM
2.3V to 3.6V DEM DEM DEM
CH1 : ASM CH1 : ASM CH1 : DEM
1.2V to 1.8V
CH2 : DEM CH2 : DEM CH2 : ASM
Below 0.8V Shutdown -- --

Diode Emulation Mode (VIN  VOUT )

ILOAD(SKIP)   tON
In diode emulation mode, the RT8230A/B/C/D/E 2L
automatically reduces switching frequency at light load where tON is the on-time.
conditions to maintain high efficiency. This reduction of The switching waveforms may appear noisy and
frequency is achieved smoothly. As the output current asynchronous when light load causes diode emulation
decreases from heavy load condition, the inductor current operation. This is normal and results in high efficiency.
is also reduced, and eventually comes to the point that Trade offs in PFM noise vs. light load efficiency is made
its current valley touches zero, which is the boundary by varying the inductor value. Generally, low inductor values
between continuous conduction and discontinuous produce a broader efficiency vs. load curve, while higher
conduction modes. To emulate the behavior of diodes, values result in higher full load efficiency (assuming that
the low-side MOSFET allows only partial negative current the coil resistance remains fixed) and less output voltage
to flow when the inductor free wheeling current becomes ripple. Penalties for using higher inductor values include
negative. As the load current is further decreased, it takes larger physical size and degraded load transient response
longer and longer time to discharge the output capacitor (especially at low input voltage levels).
to the level that requires the next “ON” cycle. The on-
In diode emulation mode, the FB voltage will rise to 2.015V
time is kept the same as that in the heavy load condition.
(typ.) naturally, because of the design circuit.
In reverse, when the output current increases from light
load to heavy load, the switching frequency increases to Ultrasonic Mode (ASM)
the preset value as the inductor current reaches the The RT8230A/B/C/D/E activates a unique type of diode
continuous conduction. The transition load point to the emulation mode with a minimum switching frequency of
light load operation is shown in Figure 1. and can be 25kHz, called ultrasonic mode. This mode eliminates
calculated as follows : audio-frequency modulation that would otherwise be
present when a lightly loaded controller automatically
IL
Slope = (VIN - VOUT) / L skips pulses. In ultrasonic mode, the low-side switch gate
IPEAK
driver signal is “OR”ed with an internal oscillator
(>25kHz). Once the internal oscillator is triggered, the
ILOAD = IPEAK / 2 controller will turn on UGATE and give it shorter on-time.
When the on-time expired, LGATE turns on until the
t inductor current goes to zero crossing threshold and keep
0 tON
both high-side and low-side MOSFET off to wait for the
next trigger. Because shorter on-time causes a smaller
Figure 1. Boundary Condition of CCM/DEM
pulse of the inductor current, the controller can keep output

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RT8230A/B/C/D/E
voltage and switching frequency simultaneously. The on- 5μA (typ.) at room temperature. The current source has a
time decreasing has a limitation and the output voltage 4700ppm/°C temperature slope to compensate the
will be lifted up under the slight load condition. The temperature dependency of the RDS(ON). When the voltage
controller will turn on LGATE first to pull down the output drop across the sense resistor or low-side MOSFET
voltage. When the output voltage is pulled down to the equals 1/10 the voltage across the RILIM resistor, positive
balance point of the output load current, the controller will current limit will be activated. The high-side MOSFET will
proceed the short on-time sequence as the above not be turned on until the voltage drop across the MOSFET
description. falls below 1/10 the voltage across the RILIM resistor.
Choose a current limit resistor according to the following
Linear Regulators (LDOx)
equation :
The RT8230A/B/C/D/E includes 5V (LDO5) and 3.3V
(LDO3) linear regulators. The regulators can supply up to VLIMIT = (RLIMIT x 5μA) / 10 = ILIMIT x RDS(ON)
100mA for external loads. Bypass LDOx with a minimum RLIMIT = (ILIMIT x RDS(ON)) x 10 / 5μA
4.7μF ceramic capacitor. When VOUT1 is higher than the
Carefully observe the PC board layout guidelines to ensure
switch over threshold (4.66V), an internal 1.5Ω P-MOSFET
that noise and DC errors do not corrupt the current sense
switch connects BYP1 to the LDO5 pin while
signal at PHASEx and GND. Mount or place the IC close
simultaneously disconnects the internal linear regulator.
to the low-side MOSFET.

Current Limit Setting (ENTRIPx) Charge Pump (SECFB)

The RT8230A/B/C/D/E has cycle-by-cycle current limit The external 14V charge pump is driven by LGATEx
control. The current limit circuit employs a unique “valley” (LGATE1 for RT8230B/E, LGATE2 for RT8230C/D). As
current sensing algorithm. If the magnitude of the current shown in Figure 3, when LGATEx is low, C1 will be charged
sense signal at PHASEx is above the current limit by VOUT1 through D1. C1 voltage is equal to VOUT1 minus
threshold, the PWM is not allowed to initiate a new cycle the diode drop. When LGATEx becomes high, C1 transfers
(Figure 2). The actual peak current is greater than the the charge to C2 through D2 and charges C2 voltage to
current limit threshold by an amount equal to the inductor VLGATEX plus C1 voltage. As LGATEx transitions low on
ripple current. Therefore, the exact current limit the next cycle, C3 is charged to C2 voltage minus a diode
characteristic and maximum load capability are a function drop through D3. Finally, C3 charges C4 through D4 when
of the sense resistance, inductor value, battery and output LGATEx switches high. Thus, the total charge pump
voltage. voltage, VCP, is :
IL

IPEAK VCP = VOUT1 + 2 x VLGATEx − 4 x VD

ILOAD where VLGATEx is the peak voltage of the LGATEx driver
which is equal to LDO5 and VD is the forward voltage
ILIMIT dropped across the Schottky diode.
t The SECFB pin in the RT8230B/C/D/E is used to monitor
Figure 2. “Valley” Current Limit the charge pump via a resistive voltage divider to generate
The RT8230A/B/C/D/E uses the on resistance of the approximately 14V DC voltage and the clock driver uses
synchronous rectifier as the current sense element and VOUT1 as its power supply. In the Figure 3 when SECFB
supports temperature compensated MOSFET RDS(ON) drops below its feedback threshold, an ultrasonic pulse
sensing. The RILIM resistor between the ENTRIPx pin and will occur to refresh the charge pump driven by LGATEx.
GND sets the current limit threshold. The resistor RILIM is If there is an overload on the charge pump in which SECFB
connected to a current source from ENTRIPx which is can not reach more than its feedback threshold, the

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 RT8230A/B/C/D/E
channel x controller will enter ultrasonic mode. Special Soft-Start
care should be taken to ensure that enough normal ripple The RT8230A/B/C/D/E provides an internal soft-start
voltage is present on each cycle to prevent charge pump function to prevent large inrush current and output voltage
shutdown. overshoot when the converter starts up. The soft-start (SS)
automatically begins once the chip is enabled. During soft-
SECFB
RCP2 start, it clamps the ramping of internal reference voltage
LGATEx
C1 C3 RCP1 which is compared with FBx signal. The typical soft-start
VOUT1 Charge Pump duration is 0.8ms. A unique PWM duty limit control that
D1 D2 D3 D4 C4
C2
prevents output over-voltage during soft-start period is
designed specifically for FBx floating.
Figure 3. Charge Pump Circuit Connected to SECFB
UVLO Protection
The RT8230A/B/C/D/E has LDO5 under-voltage lock out
MOSFET Gate Driver (UGATEx, LGATEx)
protection (UVLO). When the LDO5 voltage is lower than
The high-side driver is designed to drive high current, low
3.9V (typ.) and the LDO3 voltage is lower than 2.5V (typ.),
RDS(ON) N-MOSFET(s). When configured as a floating driver,
both switch power supplies are shut off. This is a non-
5V bias voltage is delivered from the LDO5 supply. The
latch protection.
average drive current is also calculated by the gate charge
at VGS = 5V times switching frequency. The instantaneous Power Good Output (PGOOD)
drive current is supplied by the flying capacitor between PGOOD is an open-drain output and requires a pull-up
the BOOTx and PHASEx pins. A dead-time to prevent resistor. PGOOD is actively held low in soft-start, standby,
shoot through is internally generated from high-side and shutdown. It is released when both output voltages
MOSFET off to low-side MOSFET on and low-side are above 90% of the nominal regulation point for RT8230A.
MOSFET off to high-side MOSFET on. For RT8230B/C/D/E, PGOOD is released when both output
The low-side driver is designed to drive high current low voltages are above 92.5% of nominal regulation point, and
RDS(ON) N-MOSFET(s). The internal pull down transistor the SECFB threshold is also above 50% of nominal
that drives LGATEx low is robust, with a 1Ω typical on- regulation point. The PGOOD signal goes low if either
resistance. A 5V bias voltage is delivered from the LDO5 output turns off or is 15.5% below or 13% over its nominal
supply. The instantaneous drive current is supplied by an regulation point.
input capacitor connected between LDO5 and GND.
Output Over-Voltage Protection (OVP)
For high current applications, some combinations of high
The output voltage can be continuously monitored for over-
and low-side MOSFETs may cause excessive gate drain
voltage condition. If the output voltage exceeds 13% of
coupling, which leads to efficiency killing, EMI producing,
its set voltage threshold, the over-voltage protection is
and shoot through currents. This is often remedied by
triggered and the LGATEx low-side gate drivers are forced
adding a resistor in series with BOOTx, which increases
high. This activates the low-side MOSFET switch, which
the turn-on time of the high-side MOSFET without
rapidly discharges the output capacitor and pulls the output
degrading the turn-off time. See Figure 4.
voltage downward. In addition, the BYP1 pin also has the
VIN
OVP function.
UGATEx
RBOOT When detect BYP1 Voltage over 6V, RT8230A/B/C/D/E
BOOTx
will active OVP function immediately.
PHASEx

Figure 4. Increasing the UGATEx Rise Time

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RT8230A/B/C/D/E
The RT8230A/B/C/D/E is latched once OVP is triggered Discharge Mode (Soft Discharge)
and can only be released by either toggling ENLDO, When ENTRIPx is high and a transition to standby or
ENTRIPx or cycling VIN. There is a 1μs delay built into shutdown mode occurs, or the output under-voltage fault
the over-voltage protection circuit to prevent false transition. latch is set, the output discharge mode will be triggered.
Note that latching LGATEx high will cause the output During discharge mode, an internal switch creates a path
voltage to dip slightly negative due to previously stored for discharging the output capacitors' residual charge to
energy in the LC tank circuit. For loads that cannot tolerate GND.
a negative voltage, place a power Schottky diode across
Shutdown Mode
the output to act as a reverse polarity clamp.
SMPS1, SMPS2, LDO3 and LDO5 all have independent
If the over-voltage condition is caused by a shorted in
enabling control. Drive ENLDO (RT8230A/B/D), ENC
high-side switch, turning the low-side MOSFET on 100%
(RT8230C/E), ENTRIP1 and ENTRIP2 below the precise
will create an electrical shorted circuit between the battery
input falling edge trip level to place the device in its low
and GND to blow the fuse and disconnecting the battery
power shutdown state. The RT8230A/B/C/D/E consumes
from the output.
only 10μA of input current while in shutdown. When
Output Under-Voltage Protection (UVP) shutdown mode is activated, the reference turns off. The
0.4V falling edge threshold on ENLDO/ENC can be used
The output voltage can be continuously monitored for under-
to detect a specific analog voltage level and to shutdown
voltage condition. If the output is less than 52% (typ.) of
the device. Once in shutdown, the 1V rising edge threshold
its set voltage threshold, the under-voltage protection will
activates, providing sufficient hysteresis for most
be triggered and then both UGATEx and LGATEx gate
applications.
drivers will be forced low. The UVP is ignored for at least
3ms (typ.) after a start-up or a rising edge on ENTRIPx. Power-Up Sequencing and On/Off Controls
Toggle ENTRIPx or cycle VIN to reset the UVP fault latch (ENTRIPx, ENM)
and restart the controller.
ENTRIP1 and ENTRIP2 control the power-up sequencing
Thermal Protection of the two channels of the Buck converter. When the
RT8230A/B/C/D/E is applied in the single-channel mode,
The RT8230A/B/C/D/E features thermal shutdown to
ENTRIPx disables the respective output when ENTRIPx
prevent damage from excessive heat dissipation. Thermal
voltage rises above 4.5V. Furthermore, when the RT8230A
shutdown occurs when the die temperature exceeds
is applied in the dual-channel mode, the outputs are
150°C. All internal circuitries are turned off during thermal
enabled when ENM connects to LDO3 for DEM operation.
shutdown. The RT8230A/B/C/D/E triggers thermal
shutdown if LDOx is not supplied from VOUTx, while input
voltage on VIN and drawing current from LDOx are too
high. Nevertheless, even if LDOx is supplied from VOUTx,
overloading LDOx can cause large power dissipation on
automatic switches, which may still result in thermal
shutdown.

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 RT8230A/B/C/D/E
Table 2. Operation Mode Truth Table
Mode Condition Comment

LDO Over Transitions to discharge mode after VIN POR LDO5

LDOx < UVLO threshold
Current Limit and LDO3 remain active.

ENLDO/ENC = high, VOUT1 or VOUT2 are

Run Normal Operation.
enabled
LGATEx is forced high. LDO3 and LDO5 are active.
Over-Voltage
Either output >113% of the nominal level. Exit by VIN POR or by toggling ENLDO/ENC,
Protection
ENTRIPx, and ENM.
Both UGATEx and LGATEx are forced low and enter
Either output < 52% of the nominal level
Under-Voltage discharge mode. LDO3 and LDO5 are active. Exit by
after 3ms time-out expires and output is
Protection VIN POR or by toggling ENLDO/ENC, ENTRIPx,
enabled
and ENM.
During discharge mode, there is one path to
Either output is still high in standby mode
Discharge discharge the output capacitors’ residual charge to
or shutdown mode
GND via an internal switch.
ENTRIPx > startup threshold or ENM <
Standby LDO3 and LDO5 are active.
startup threshold, ENLDO/ENC = high.
All circuitries are off. LDO3 and LDO5 are kept
Shutdown ENLDO/ENC = low
active for RT8230C/E only.
Thermal All circuitries are off. Exit by VIN POR or by toggling
TJ > 150°C
Shutdown ENLDO/ENC, ENTRIPx, and ENM.

Table 3. Power-Up Sequencing (RT8230A)

ENTRIP1 ENTRIP2
ENLDO (V) ENM (V) LDO5 LDO3 SMPS1 SMPS2
(V) (V)

Low Low X X Off Off Off Off

“>1V”
Low X X On On Off Off
=> High

“>1V” “>2.3V”
Off Off On On Off Off
=> High => High

“>1V” “>2.3V”
Off On On On Off On
=> High => High

“>1V” “>2.3V”
On On On On On On
=> High => High

“>1V” “>2.3V”
On Off On On On Off
=> High => High

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RT8230A/B/C/D/E
Output Voltage Setting (FBx) Output Capacitor Selection
Connect a resistive voltage divider at the FBx pin between The capacitor value and ESR determine the amount of
VOUTx and GND to adjust the output voltage from 2V to output voltage ripple and load transient response. Thus,
5.5V for CH1 and 2V to 4V for CH2 as shown in the capacitor value must be greater than the largest value
Figure 5. Choose R2 to be approximately 10kΩ, and solve calculated from the equations below :
for R1 using the equation below :
(ILOAD )2  L  (tON + tOFF(MIN) )
  R1   VSAG 
VOUT  VFBx   1 +   2  COUT   VIN  tON  VOUTx (tON + tOFF(MIN) )
  R2  
where VFBx is 2V (typ.).
(ILOAD )2  L
VIN VSOAR 
2  COUT  VOUTx

UGATEx  1 
VPP  LIR  ILOAD(MAX)   ESR + 
VOUTx  8  COUT  f 
PHASEx

LGATEx where VSAG and VSOAR are the allowable amount of

R1
PGND undershoot and overshoot voltage during load transient,
FBx Vp-p is the output ripple voltage, and tOFF(MIN) is the
R2
minimum off-time.
GND

Thermal Considerations
Figure 5. Setting VOUTx with a resistive voltage divider
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
Output Inductor Selection
dissipation depends on the thermal resistance of the IC
The switching frequency (on-time) and operating point
package, PCB layout, rate of surrounding airflow, and
(% ripple or LIR) determine the inductor value as shown
difference between junction and ambient temperature. The
below :
maximum power dissipation can be calculated by the
t  (VIN  VOUTx )
L  ON following formula :
LIR  ILOAD(MAX)
PD(MAX) = (TJ(MAX) − TA) / θJA
where LIR is the ratio of the peak-to-peak ripple current to
where TJ(MAX) is the maximum junction temperature, TA is
the average inductor current.
the ambient temperature, and θJA is the junction to ambient
Find a low-loss inductor having the lowest possible DC thermal resistance.
resistance that fits in the allotted dimensions. Ferrite cores
For recommended operating condition specifications, the
are often the best choice, although powdered iron is
maximum junction temperature is 125°C. The junction to
inexpensive and can work well at 200kHz. The core must
ambient thermal resistance, θJA, is layout dependent. For
be large enough not to saturate at the peak inductor
WQFN-20L 3x3 package, the thermal resistance, θJA, is
current, IPEAK :
30°C/W on a standard JEDEC 51-7 four-layer thermal test
IPEAK = ILOAD(MAX) + [ (LIR / 2) x ILOAD(MAX) ] board. The maximum power dissipation at TA = 25°C can
The calculation above shall serve as a general reference. be calculated by the following formula :
To further improve transient response, the output P D(MAX) = (125°C − 25°C) / (30°C/W) = 3.33W for
inductance can be further reduced. Of course, besides WQFN-20L 3x3 package
the inductor, the output capacitor should also be
considered when improving transient response.

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 RT8230A/B/C/D/E
The maximum power dissipation depends on the operating Layout Considerations
ambient temperature for fixed T J(MAX) and thermal Layout is very important in high frequency switching
resistance, θJA. The derating curve in Figure 6 allows the converter design. Improper PCB layout can radiate
designer to see the effect of rising ambient temperature excessive noise and contribute to the converter’s
on the maximum power dissipation. instability. Certain points must be considered before
4.0 starting a layout with the RT8230A/B/C/D/E.
Maximum Power Dissipation (W)1

Four-Layer PCB
3.5  Place the filter capacitor close to the IC, within 12mm
3.0 (0.5 inch) if possible.

2.5  Keep current limit setting network as close as possible

2.0
to the IC. Routing of the network should avoid coupling
to high-voltage switching node.
1.5
 Connections from the drivers to the respective gate of
1.0
the high-side or the low-side MOSFET should be as
0.5 short as possible to reduce stray inductance. Use
0.0 0.65mm (25 mils) or wider trace.
0 25 50 75 100 125
 All sensitive analog traces and components such as
Ambient Temperature (°C)
FBx, ENTRIPx, PGOOD, and TON should be placed
Figure 6. Derating Curve of Maximum Power Dissipation away from high voltage switching nodes such as
PHASEx, LGATEx, UGATEx, or BOOTx nodes to avoid
coupling. Use internal layer(s) as ground plane(s) and
shield the feedback trace from power traces and
components.
 Place ground terminal of VIN capacitor(s), V OUTx
capacitor(s), and Source of low-side MOSFETs as close
to each other as possible. The PCB trace of PHASEx
node, which connects to Source of high-side MOSFET,
Drain of low-side MOSFET and high voltage side of the
inductor, should be as short and wide as possible.

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RT8230A/B/C/D/E
Outline Dimension

1 1

2 2

DETAIL A
Pin #1 ID and Tie Bar Mark Options

Note : The configuration of the Pin #1 identifier is optional,

but must be located within the zone indicated.

Dimensions In Millimeters Dimensions In Inches

Symbol
Min Max Min Max
A 0.700 0.800 0.028 0.031
A1 0.000 0.050 0.000 0.002
A3 0.175 0.250 0.007 0.010
b 0.150 0.250 0.006 0.010
D 2.900 3.100 0.114 0.122
D2 1.650 1.750 0.065 0.069
E 2.900 3.100 0.114 0.122
E2 1.650 1.750 0.065 0.069
e 0.400 0.016
L 0.350 0.450 0.014 0.018

W-Type 20L QFN 3x3 Package

Richtek Technology Corporation

14F, No. 8, Tai Yuen 1st Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789

Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot
assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be
accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.

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