MP3388

50V, 8-String White LED Driver

The Future of Analog IC Technology

DESCRIPTION FEATURES
The MP3388 is a step-up converter with • High Efficiency and Small Size
8-channel current sources designed for driving • 4.5V to 25V Input Voltage Range
the white LED arrays for large size LCD panel • 50V Maximum Step-up Voltage
backlighting applications. • Balanced Driver for 8 Strings of WLED
The MP3388 uses current mode, fixed frequency • 3% Current Matching Accuracy Between
architecture. The switching frequency can be Strings
selected at 1.25MHz or 625kHz. It generates an • Selectable Switching Frequency: 1.25MHz or
output voltage up to 50V from a 4.5V to 25V input 625kHz
supply. The MP3388 independently regulates the • PWM or DC Input Burst PWM Dimming
current in each LED string to the user programmed • Programmable Over-voltage Protection
value set by an external current setting resistor. • Under Voltage Lockout
The MP3388 applies 8 internal current sources in • Open and Short LED protection
each LED string terminal to achieve a current • Thermal Shutdown
balance of 3% regulation accuracy between • Small QFN24 (4x4mm) and 28 pin SOIC
strings. Its low 600mV regulation voltage on LED packages
current sources reduces power loss and improves • Halogens Free
efficiency.
APPLICATIONS
The MP3388 features external PWM dimming or • Notebook PC
DC input PWM dimming, which allows the flexible
• Small LCD TV
control of the backlighting luminance. The dimming
• Handy Terminals Display
PWM signal can be generated internally, and the
• Automotive System and Tablet Computer
dimming frequency is programmed by an external
setting capacitor. All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.

TYPICAL APPLICATION M1 D1
L1
VIN
C1 C2
4.5V~25V R1

R2

C3 C4
24 23 22 21 20 19

VCC VIN COMP VFAULT SW1 SW2

Enable 1
EN PGND1
18

2 17
NC OSC PGND2

3 16
FSET OVP

4
MP3388 15
PWMO LED1

C5 C6
5 14
GND LED2

PWM 6
PWMI LED3
13

DIMMING
LED8 LED7 LED6 LED5 ISET LED4

7 8 9 10 11 12

R SET

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

ORDERING INFORMATION
Part Number Package Top Marking Free Air Temperature (TA)
MP3388DR* QFN24 (4x4mm) 3388DR -40°C TO +85°C
MP3388EY SOIC28 MP3388EY -20°C TO +85°C

* For Tape & Reel, add suffix –Z (e.g. MP3388DR–Z).

For RoHS Compliant Packaging, add suffix –LF (e.g. MP3388DR–LF–Z)

PACKAGE REFERENCE
TOP VIEW TOP VIEW
VFAULT
COMP
VCC

VFAULT 1 28 SW1
SW1

SW2
VIN

COMP 2 27 NC
24 23 22 21 20 19 VIN 3 26 SW2

VCC 4 25 NC
EN 1 18 PGND1
EN 5 24 PGND1
OSC 2 17 PGND2 OSC 6 23 PGND2

FSET 3 Exposed Pad 16 OVP FSET 7 22 OVP

Connect to GND PWMO 8 21 LED1
PWMO 4 15 LED1
GND 9 20 LED2
GND 5 14 LED2 PWMI 10 19 LED3
LED8 11 18 LED4
PWMI 6 13 LED3
LED7 12 17 NC
7 8 9 10 11 12 LED6 13 16 ISET
LED8

LED7

LED6

LED5

LED4

LED5 NC
ISET

14 15

QFN24 (4X4mm) SOIC28

ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance

(4)
θJA θJC
VIN .................................................-0.3V to +30V QFN24 (4x4mm) ...................42 ....... 9 .... °C/W
VVFAULT ........................................... VIN - 6V to VIN SOIC28 .................................60 ...... 30 ... °C/W
VSW ................................................-0.3V to +50V
VLED1 to VLED8 .................................-0.3V to +50V Notes:
1) Exceeding these ratings may damage the device.
All Other Pins ..................................-0.3V to +6V 2) The maximum allowable power dissipation is a function of the
Continuous Power Dissipation (TA = +25°C) (2) maximum junction temperature TJ (MAX), the junction-to-ambient
QFN24 (4x4mm)………………………….....2.9W thermal resistance θJA, and the ambient temperature TA. The
maximum allowable continuous power dissipation at any
SOIC28…………………………… ……....2.1W ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA.
Junction Temperature ...............................150°C Exceeding the maximum allowable power dissipation will
cause excessive die temperature, and the regulator will go into
Lead Temperature ....................................260°C thermal shutdown. Internal thermal shutdown circuitry protects
Storage Temperature............... -65°C to +150°C the device from permanent damage.
3) The device is not guaranteed to function outside of its
(3)
Recommended Operating Conditions operation conditions.
4) Measured on JESD51-7, 4-layer PCB.
Supply Voltage VIN ...........................4.5V to 25V
Maximum Junction Temp. (TJ) ..................125°C

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

ELECTRICAL CHARACTERISTICS
VIN =12V, VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters Symbol Condition Min Typ Max Units

Operating Input Voltage VIN 4.5 25 V

Supply Current (Quiescent) IQ VIN=12V, VEN=5V, no load. 1.8 mA

Supply Current (Shutdown) IST VEN=0V, VIN=12V 2 μA

VEN=5V, 6V<VIN<25V,
LDO Output Voltage VCC 4.5 5 5.5 V
0<IVCC<10mA
Input UVLO Threshold VIN_UVLO Rising Edge 3.4 3.9 4.3 V
Input UVLO Hysteresis 200 mV
EN ON Threshold VEN_ON VEN Rising 1.8 V
EN OFF Threshold VEN_OFF VEN Falling 0.6 V
STEP-UP CONVERTER
SW On-Resistance RDS_ON IDS=20mA 0.18 0.3 Ω
SW Leakage Current ISW_LK VSW=45V 1 μA
VOSC=VCC or Floating 1.0 1.25 1.5 MHz
Switching Frequency fSW
VOSC=0V 500 625 750 kHz
OSC High-Level Threshold VOSC_H 2.1 V
OSC Low-Level Threshold VOSC_L 0.8 V
PWM Mode,
Minimum On Time TON_MIN 100 ns
when no pulse skipping happens
Maximum Duty Cycle DMAX 90 93 96 %
SW Current Limit ISW_LIMIT Duty=90% 2.0 A
COMP Transconductance GCOMP ΔICOMP=±10uA 100 μA/V
COMP Output Current ICOMP 60 uA
PWM DIMMING
PWMI High-Level Threshold VPWMI_H 1.5 V
PWMI Low-Level Threshold VPWMI_L 0.8 V
PWMO Output Impedance RPWMO 300 400 500 kΩ
PWMI Leakage Current IPWMI_LK -1 +1 μA
DPWM Frequency fDPWM CFSET=2.2nF 1.2 1.6 2 kHz

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

ELECTRICAL CHARACTERISTICS (continued)

VIN =12V, VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters Symbol Condition Min Typ Max Units
LED CURRENT REGULATION
LEDX Average Current ILED RISET=60.4kΩ 19.2 19.9 20.6 mA
(5)
Current Matching ILED=20mA 3 %
Maximum LED Current per String ILEDmax RISET=40.2 kΩ 30 mA
LEDX Regulation Voltage VLEDX ILED=20mA 600 mV
PROTECTION
OVP Over Voltage Threshold VOVP_OV Rising Edge 1.17 1.23 1.3 V
OVP UVLO threshold VOVP_UV Step-up Converter Fails 48 70 102 mV
LEDX Over Voltage Threshold VLEDX_OV VIN>5.5V 5.1 5.5 5.9 V
LEDX UVLO Threshold VLEDX_UV 130 175 230 mV
Thermal Shutdown Threshold TST 150 ℃
LEDX Over Voltage Fault Timer 1.3 1.6 1.9 ms
VFAULT Pull Down Current IFAULT 40 55 70 μA
VFAULT Blocking-Off Voltage
VFAULT VIN =12V, VIN-VFAULT 6 V
(with Respect to VIN)
Notes:
5) Matching is defined as the difference of the maximum to minimum current divided by 2 times average currents.

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

PIN FUNCTIONS
QFN24 SOIC28 Name Description
1 5 EN Enable Control Input. Do not let this pin floating.
Switching Frequency Selection Input. When float this pin or connect this pin to
2 6 OSC VCC, the step-up converter switching frequency is 1.25MHz. When connect this
pin to GND, the step-up converter switching frequency is 625kHz.

Dimming PWM Frequency Setting. Connect a capacitor between FSET and GND
3 7 FSET
to set the DPWM frequency by the equation: fDPWM=3.5uF/CFSET.
PWM Filter Output. To use external PWM dimming mode, connect a capacitor
between PWMO and GND to form a low-pass filter with an internal 400kΩ resistor.
It filters the external PWM logic signal on PWMI pin into a DC signal whose level is
inversely proportional to the duty-cycle of the input PWM signal. Then the DC
4 8 PWMO
signal is converted to a DPWM dimming signal with the same duty-cycle as the
external PWM signal. To use DC input PWM dimming mode, directly apply a DC
voltage from 0.2V to 1.2V on PWMO pin for dimming PWM duty cycle control. The
DC input PWM dimming polarity is negative.
5 9 GND Analog Ground.
PWM Signal Input. To use the external PWM dimming mode, apply a PWM signal
on this pin for brightness control. This signal is filtered and its duty cycle is
6 10 PWMI converted into a DC signal to calculate the DPWM duty cycle. And the DPWM duty
cycle equals to the input PWM duty cycle. To use DC input PWM dimming mode,
float this pin.
LED String 8 Current Input. This pin is the open-drain output of an internal
7 11 LED8 dimming control switch. Connect the LED String 8 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED String 7 Current Input. This pin is the open-drain output of an internal
8 12 LED7 dimming control switch. Connect the LED String 7 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED String 6 Current Input. This pin is the open-drain output of an internal
9 13 LED6 dimming control switch. Connect the LED String 6 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED String 5 Current Input. This pin is the open-drain output of an internal
10 14 LED5 dimming control switch. Connect the LED String 8 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED Current Setting. Tie a current setting resistor from this pin to ground to
11 16 ISET
program the current in each LED string. ILED = 1000 x 1.22V /( RSET+1kΩ)
LED String 4 Current Input. This pin is the open-drain output of an internal
12 18 LED4 dimming control switch. Connect the LED String 4 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED String 3 Current Input. This pin is the open-drain output of an internal
13 19 LED3 dimming control switch. Connect the LED String 3 cathode to this pin. If this string
is not used, connect Vout to this pin.
LED String 2 Current Input. This pin is the open-drain output of an internal
14 20 LED2 dimming control switch. Connect the LED String 2 cathode to this pin. If this string
is not used, connect Vout to this pin.

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

PIN FUNCTIONS (continued)

QFN24 SOIC28 Name Description
LED String 1 Current Input. This pin is the open-drain output of an internal
15 21 LED1 dimming control switch. Connect the LED String 1 cathode to this pin. If this
string is not used, connect Vout to this pin.
Over-voltage Protection Input. Connect a resistor divider from output to this
16 22 OVP pin to program the OVP threshold. When this pin voltage reaches 1.23V, the
MP3388 triggers OV Protection mode.
17 23 PGND2 Step-up Converter Power Ground.
Step-up Converter Power Ground. PGND1 and PGND2 should be shorted
18 24 PGND1 externally.
Step-up Converter Power Switch Output. SW2 is the drain of the internal
MOSFET switch. Connect the power inductor and output rectifier to SW2.
19 28 SW2 SW2 can swing between GND and 50V. SW1 and SW2 should be shorted
externally.
Step-up Converter Power Switch Output. SW1 is the drain of the internal
MOSFET switch. Connect the power inductor and output rectifier to SW1.
20 26 SW1
SW1 can swing between GND and 50V. SW1 and SW2 should be shorted
externally.
Fault Disconnection Switch Driver Output. When the system starts up
21 1 VFAULT normally, this pin turns on the external PMOS. When the MP3388 is disabled,
the external PMOS is turned off to disconnect the input and output.
Step-up Converter Compensation Pin. This pin is used to compensate the
22 2 COMP regulation control loop. Connect a capacitor or a series RC network from
COMP to GND.
Supply Input. VIN supplies the power to the MP3388 chip. Drive VIN with a
23 3 VIN
4.5V to 25V power source. Must be locally bypassed.
The Internal 5V Linear Regulator Output. VCC provides power supply for the
internal MOSFET switch gate driver and the internal control circuitry. Bypass
24 4 VCC VCC to GND with a ceramic capacitor. If VIN is less than 5.5V, apply an
external 5V supply directly on VCC.
15, 17,
NC No connect
25, 27

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

TYPICAL PERFORMANCE CHARACTERISTICS

VIN =15V, 10 LEDs in series, 8 strings parallel, 20mA/string, unless otherwise noted.
Efficiency vs. Input Voltage Steady State Vin Startup

100
EFFICIENCY(%)

95 Vsw
Vsw
20V/div 20V/div
90
VOUT
85 VLED8 20V/div
500mV/div
VIN
80 10V/div
VOUT/AC
500mV/div
75 ILED ILED
100mA/div 100mA/div
70
4 9 14 19 24 29
INPUT VOLTAGE (V) 400ns/div 2ms/div

Ven Startup PWM Dimming Open LED Protection

fPWM=2kHz, DPWM=50% open all LED strings at working

Vsw Vsw Vsw

20V/div 20V/div 20V/div

VOUT VOUT
20V/div 20V/div
VPWMI VOUT
VEN 5V/div 20V/div
5V/div
VFAULT
ILED 5V/div
ILED ILED
100mA/div 100mA/div
100mA/div
2ms/div 200us/div 400ms/div

Short LED Protecton Short LED Protection

short Vout to LEDx at working short Vout to GND at working

Vsw Vsw
20V/div 20V/div

VOUT VOUT
20V/div 20V/div
VLED8
20V/div VFAULT
10V/div
ILED ILED
100mA/div 100mA/div

1ms/div 200us/div

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

FUNCTION DIAGRAM
VCC VFAULT SW

VIN Regulator

GND
-
Control
+ Logic

PWM
Comparator
Current Sense
Amplifier
+

- PGND
OV
Comparator
+ OVP
OSC Oscillator
- 1.23V
LED OV
Comparator

Short String - 5.5V

Protection + Max
Feedback
Control
- Min
COMP EA
+ 600mV

Enable
EN Control
LED1
1.22V +

ISET
Current Control

DPWM LED8
FSET Oscillator

1.2V -
400k? DPWM
PWMI Comparator

0.2V

PWMO

Figure 1—MP3388 Function Diagram

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

OPERATION
The MP3388 employs a constant frequency, peak output of the current sense amplifier and the
current mode step-up converter and 8-channels result is fed into the PWM comparator. When this
regulated current sources to regulate the array of result voltage reaches the output voltage of the
8 strings white LEDs. The operation of the error amplifier (VCOMP) the power FET is turned
MP3388 can be understood by referring to the off.
block diagram of Figure 1. The voltage at the output of the internal error
Internal 5V Regulator amplifier is an amplified signal of the difference
between the 600mV reference voltage and the
The MP3388 includes an internal linear regulator feedback voltage. The converter automatically
(VCC). When VIN is greater than 5.5V, this chooses the lowest active LEDX pin voltage for
regulator offers a 5V power supply for the internal providing enough bus voltage to power all the
MOSFET switch gate driver and the internal LED arrays.
control circuitry. The VCC voltage drops to 0V
when the chip shuts down. In the application of If the feedback voltage drops below the 600mV
VIN smaller than 5.5V, tie VCC and VIN together. reference, the output of the error amplifier
The MP3388 features Under Voltage Lockout. increases. It results in more current flowing
The chip is disabled until VCC exceeds the UVLO through the power FET, thus increasing the
threshold. And the hysteresis of UVLO is power delivered to the output. In this way it forms
approximately 200mV. a close loop to make the output voltage in
regulation.
System Startup
At light-load or Vout near to Vin operation, the
When the MP3388 is enabled, the chip checks converter runs into the pulse-skipping mode, the
the topology connection first. The VFAULT pin FET is turned on for a minimum on-time of
drives the external Fault Disconnection PMOS to approximately 100ns, and then the converter
turn on slowly. And after 400us delay, the chip discharges the power to the output in the remnant
monitors the OVP pin to see if the Schottky diode period. The FET will keep off until the output
is not connected or the boost output is short to voltage needs to be boosted again.
GND. If the OVP voltage is lower than 70mV, the
chip will be disabled and the external PMOS is Dimming Control
turned off together. The MP3388 will also check The MP3388 provides several PWM dimming
other safety limits, including UVLO,and OTP after methods: external PWM signal from PWMI pin or
the OVP test is passed. If they are all in function, DC input PWM Dimming mode (see Figure 2).
it then starts boosting the step-up converter with These methods results in PWM chopping of the
an internal soft-start. current in the LEDs for all 8 channels to provide
LED control.
It is recommended on the start up sequence that
the enable signal comes after input voltage and DC Input

PWM dimming signal established. Ex-PWM Input 1.2V DPWM

Comparator DPWM Output
400 k?
-
Step-up Converter PWMI
CPWMO
PWMO
+
0.2V
The converter operation frequency is selectable
(1.25MHz or 625kHz), which is helpful for 1.2V

optimizing the external components sizes and DPWM

0.2V

improving the efficiency. Oscillator

FSET
C FSET
At the beginning of each cycle, the power FET is
turned with the internal clock. To prevent
sub-harmonic oscillations at duty cycles greater Figure 2—PWM Dimming Method
than 50 percent, a stabilizing ramp is added to the

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

When applying a PWM signal to the PWMI pin, will force the output voltage back into tight
the MP3388 generates a DC voltage on PWMO regulation. The string with the highest voltage
pin which is reversely proportional to the duty drop is the ruling string during output regulation.
cycle of the PWMI pin signal. By comparing the
The MP3388 always tries to light at least one
PWMO pin signal with the FSET pin triangle
string and if all strings in use are open, the
waveform, the converter gets a low frequency
MP3388 shuts down the step-up converter. The
chopping signal that the duty cycle is same as the
part will maintain mark-off information until the
input signal. This low frequency chopping signal
part shuts down.
will modulate the LED current.
A DC analog signal can be directly applied to the
Short String Protection
PWMO pin to modulate the LED current. And the The MP3388 monitors the LEDX pin voltage to
DC signal is then converted to a DPWM dimming judge if the short string occurs. If one or more
signal at the setting oscillation frequency. The strings are short, the respective LEDX pins will be
polarity is negative. pulled up to the boost output and tolerate high
voltage stress. If the LEDX pin voltage is higher
The brightness of the LED array is proportional to
than 5.5V, the short string condition is detected
the duty cycle of the DPWM signal. The DPWM
on the respective string. When the short string
signal frequency is set by the cap at the FSET
pin. fault (LEDX over-voltage fault) continues for
greater than 1.6ms, the string is marked off and
Open String Protection disabled. Once a string is marked off, its current
The open string protection is achieved through regulation is forced to disconnect from the output
the over voltage protection. If one or more strings voltage loop regulation. The marked-off LED
are open, the respective LEDX pins are pulled to strings will be shut off totally until the part restarts.
ground and the IC keeps charging the output If all strings in use are short, the MP3388 will shut
voltage until it reach OVP threshold. Then the down the step-up converter.
part will mark off the open strings whose LEDX
pin voltage is less than 175mV. Once the mark-off
operation completes, the remaining LED strings

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

APPLICATION INFORMATION The minimum recommended amplitude of the

PWM signal is 2.1V (See Figure 3)
Selecting the Switching Frequency
The switching frequency of the step-up converter FSET

is alternative for 1.25MHz or 625kHz. A bi-level C1

MP3388
Switching Frequency Selection (OSC) input sets PWM Dimming
the internal oscillator frequency for the step-up 100Hz~50kHz PWMI

PWMO
converter. Tie OSC pin to GND corresponds to
the frequency 625kHz and tie OSC pin to VCC or
C2

floating corresponds to 1.25MHz.

Figure 3—PWM Dimming
Setting the LED Current with Internal Triangle Waveform Generator
The LED string currents are identical and set
through the current setting resistor on the ISET 2. Direct PWM dimming with positive logic
pin. An external PWM dimming signal is directly
ILED = 1000 x 1.22V / (RSET+1kΩ) employed to achieve PWM dimming control.
Connect a 100kΩ resistor from FSET pin to GND
For RSET=60.4kΩ, the LED current is set to
and apply the 100Hz to 2kHz PWM dimming
19.9mA. The ISET pin can not be open.
signal to PWMI pin. The minimum recommended
Setting the Over Voltage Protection amplitude of the PWM signal is 1.5V (See Figure
The open string protection is achieved through 4).
the over voltage protection (OVP). In some cases, C1

an LED string failure results in the feedback

voltage always zero. The part then keeps VCC

boosting the output voltage higher and higher. If R1

FSET

the output voltage reaches the programmed OVP 100 kO

MP3388

threshold, the protection will be triggered. PWM Dimming

100Hz~2kHz PWMI

To make sure the chip functions properly, the

PWMO

OVP setting resistor divider must be set with a

proper value. The recommended OVP point is Figure 4—Direct PWM Dimming
about 1.3 times higher than the output voltage for with Positive Logic
normal operation.
3. Direct PWM dimming with negative logic
VOVP=1.23V x (R1+R2)/R2
It is similar to method 2. Apply a 100Hz to 2 kHz
Selecting Dimming Control Mode external square waveform to the PWMO pin for
The MP3388 provides 4 different dimming negative logic PWM dimming. The minimum
methods recommended amplitude of the PWM signal is
1. PWM dimming mode with internal triangle 1.5V (See Figure 5),
waveform generator C1

Apply a 100Hz to 50kHz square waveform to the VCC

PWMI pin. The internal 400kΩ and external FSET

capacitor on PWMO pin filters the dimming signal R1

100 kO
MP3388
to a DC voltage(0.2V~1.2V).Then the DC voltage
is modulated to an internal PWM dimming signal PWMI

whose frequency is set via the capacitor on FSET PWM Dimming

PWMO

pin according to the equation: 100Hz~2kHz

fDPWM = 3.5uF / CFSET Figure 5— Direct PWM Dimming

with Negative Logic

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

4. DC input PWM dimming Layout Considerations

To apply DC input PWM dimming, apply an Careful attention must be paid to the PCB board
analog signal (range from 0.2V to 1.2V) to the layout and components placement. Proper layout
PWMO pin to modulate the LED current directly. of the high frequency switching path is critical to
If the PWMO is applied with a DC voltage<0.2V, prevent noise and electromagnetic interference
the PWM duty cycle will be 100%. If the PWMO problems. The loop of MP3388 SW to PGND pin
pin is applied with a DC voltage>1.2V, the output (U1), output diode (D1), and output capacitor (C3)
will be 0% (See Figure 6). The capacitor on FSET is flowing with high frequency pulse current. it
pin set the frequency of internal triangle must be as short as possible (See Figure 7).
waveform.
U1 SW
D1
FSET
C1 PGND
MP3388
C2
PWMI

Analog Dimming PWMO

0.2V~1.2V
GND
Figure 6—DC input PWM dimming Iset
Rset R2 R1
Selecting the Inductor
A 10μH (for 1.25MHz switching frequency) /22uH Figure 7—Layout Consideration
(for 625kHz switching frequency) inductor with a
DC current rating of at least 40% higher than the The IC exposed pad is internally connected to
maximum input current is recommended for most GND pin, and all logic signals are refer to the
applications. For highest efficiency, the inductor’s GND. The PGND should be externally connected
DC resistance should be as small as possible. to GND and is recommended to keep away from
the logic signals.
Selecting the Input Capacitor
The input capacitor reduces the surge current
drawn from the input supply and the switching
noise from the device. The input capacitor
impedance at the switching frequency should be
less than the input source impedance to prevent
high frequency switching current from passing
through the input. Ceramic capacitors with X5R or
X7R dielectrics are highly recommended because
of their low ESR and small temperature
coefficients. For most applications, a 4.7μF
capacitor is sufficient.
Selecting the Output Capacitor
The output capacitor keeps the output voltage
ripple small and ensures feedback loop stability.
The output capacitor impedance should be low at
the switching frequency. Ceramic capacitors with
X7R dielectrics are recommended for their low
ESR characteristics. For most applications, a
2.2μF ceramic capacitor will be sufficient.

MP3388 Rev. 1.0 www.MonolithicPower.com 12

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 MP3388- 50V, 8-STRING WHITE LED DRIVERS

PACKAGE INFORMATION
QFN24 (4mm x 4mm)
3.90 2.50
4.10 2.80
PIN 1 ID
19 24 SEE DETAIL A
PIN 1 ID
MARKING
18 1
0.50
3.90 BSC 2.50
PIN 1 ID 2.80
4.10
INDEX AREA
0.18
0.30
13 6

0.35 12 7
0.45
TOP VIEW BOTTOM VIEW

PIN 1 ID OPTION A PIN 1 ID OPTION B

0.30x45º TYP. R0.25 TYP.
0.80
1.00
0.20 REF
0.00
0.05

SIDE VIEW DETAIL A

3.90 NOTE:
2.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
0.70 2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) DRAWING CONFIRMS TO JEDEC MO-220, VARIATION VGGD.
0.25
5) DRAWING IS NOT TO SCALE.

0.50

RECOMMENDED LAND PATTERN

MP3388 Rev. 1.0 www.MonolithicPower.com 13

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© 2011 MPS. All Rights Reserved.
 MP3388- 50V, 8-STRING WHITE LED DRIVERS

PACKAGE INFORMATION (continued)

SOIC28
0.697(17.70) 0.024 0.050
0.713(18.10) (0.61) (1.27)
28 15
0.079
(2.00)

0.291 0.394
(7.40) (10.00) 0.370
0.299 0.418 (9.40)
(7.60) (10.60)

PIN 1 ID

1 14

TOP VIEW RECOMMENDED LAND PATTERN

0.093(2.35)
0.104(2.65) 0.009(0.23)
SEATING PLANE
0.013(0.33)
0.013(0.33) 0.050(1.27) 0.004(0.10)
0.020(0.51) BSC 0.012(0.30) SEE DETAIL "A"

FRONT VIEW SIDE VIEW

0.010(0.25)
x 45o NOTE:
0.030(0.75)

GAUGE PLANE 1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN

0.010(0.25) BSC BRACKET IS IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSIONS OR GATE BURRS.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
0.016(0.41) OR PROTRUSIONS.
0o-8o 0.050(1.27) 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.10 MILLIMETERS MAX.
5) DRAWING CONFORMS TO JEDEC MS-013, VARIATION AE.
DETAIL "A" 6) DRAWING IS NOT TO SCALE.

NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.

MP3388 Rev. 1.0 www.MonolithicPower.com 14

12/16/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2011 MPS. All Rights Reserved.