Datasheet

Current Mode PWM Controller SDC3842/3843/3844/3845

General Description Features

The SDC384X are high performance fixed frequency Start-up current: 0.15mA

T

current-mode PWM controller series. These integrated  Low line regulation: 4mV
circuits are optimized for off-line and DC-DC converter
applications with minimum external components. They
feature under-voltage lockout (UVLO) circuit with low



Low load regulation: 4mV
Operating frequency up to 500kHz
E N
High PWM frequency stability over a full
start-up current, trimmed oscillator for precise duty temperature range: 2.5%
M
cycle control, current sense comparator providing
maximum current limiting and a totem pole output

voltage range: 0.2% U
High PWM frequency stability under a full supply

stage for increasing output current. In addition, these 

C
Accurate over-temperature
ICs also feature accurate protection against
over-temperature, over-current and maximal output

 O
Protection with hysteresis
UVLO with hysteresis
power. 
D
Package: SOP-8, DIP-8

The SDC3842 and SDC3844 have UVLO thresholds of

16V(ON) and 10V(OFF); The corresponding thresholds
A L
Applications

for SDC3843 and SDC3845 are 8.4V(ON) and 7.6V(OFF).

The SDC3842 and SDC3843 can operate approaching

T I



Off-line converter
DC-DC converter
Voltage adapter
100% duty cycle; SDC 3844 and SDC3845 can operate
from zero to 50% duty cycle.
E N 

CRT monitor power supply
DVD/STB power supply

I D
F
N
O
C
C
S D DIP-8

Figure 1. Package Type

SOP-8

December, 2013 Rev. 1.2 1/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Pin Configuration
Package: DIP-8 Package: SOP-8

COMP 1 8 VREF COMP 1 8 VREF

T
FB

CS
2

3
7

6
VCC

OUTPUT
FB

CS
2

3
7

6
VCC

OUTPUT
E N
RT/CT 4 5 GND RT/CT 4 5 GND
M
U
Pin Number Pin Name
Figure 2. Pin Configuration

Function C
1 COMP
O
This pin is the error amplifier output and is made available for loop compensation

2 FB
supply output through a resistor divider D
The inverting input of the error amplifier. It is normally connected to the switching power

3 CS
A L
A voltage proportional to inductor current is connected to this input. The PWM uses this

4 RT/CT
T I
information to terminate the output switch conduction
The oscillator frequency and maximum output duty cycle are programmed by connecting
resistor RT to VREF and capacitor CT to ground. Operation to 500 kHz is possible
5

6
GND

OUTPUT
E N
The combined control circuitry and power ground
This output directly drives the gate of a power MOSFET. Peak currents up to 1.0 A are
sourced and sunk by this pin
7 VCC
I D
The positive supply of the control IC

8 VREF
RT F
This is the reference output. It provides charging current for capacitor CT through resistor

N
O Table 1. Pin Description

C
C
S D

December, 2013 Rev. 1.2 2/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Functional Block Diagram

T
VCC

34V 8
5 UVLO S/R 5VREF VREF
GND

2.50V
INTERNAL
BIAS
E N
VREF GOOD
M
LOGIC

U 6
OUTPUT

C
4
RT/CT OSC T

OVER TEMP
PROTECTION O
S
D
L
2 + 2R
FB - R
1 R 1V

A
COMP
3
CS

T I
N
Figure 3. Functional Block Diagram

E
I D
F
N
O
C
C
S D

December, 2013 Rev. 1.2 3/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Ordering Information
SDC384X X X - X
E1: Pb-free
Circuit Type
Package
G1: Halogen-free
T
DIP-8: Z
SOP-8: U
Part Number
Blank: Tube
TR: Tape Reel

Marking ID E N Packing
Package Temperature
Pb-free Halogen-free Pb-free
M
Halogen-free Type

DIP-8 -40℃~85℃ SDC3842/3/4/5Z-E1 SDC3842/3/4/5Z-G1 SDC3842/3/4/5

U
SDC3842/3/4/5G Tube
Tape
SOP-8 -40℃~85℃ SDC3842/3/4/5UTR-E1 SDC3842/3/4/5UTR-G1 SDC3842/3/4/5
C SDC3842/3/4/5G
Reel
SOP-8 -40℃~85℃ SDC3842/3/4/5U-E1 SDC3842/3/4/5U-G1
O
SDC3842/3/4/5 SDC3842/3/4/5G Tube

D
A L
T I
E N
I D
F
N
O
C
C
S D

December, 2013 Rev. 1.2 4/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Absolute Maximum Ratings (NOTE: Stresses greater than those listed under Absolute Maximum Ratings may cause
permanent damage to the device.)
Parameter Symbol Value Unit
Supply voltage V CC 30 V
Output current IO ±1 A T
Analog inputs (pin2/pin3)
Error amp output sink current
VA
I SINK
-0.3~6.3
10
E NV
mA
Power dissipation at Ta< 25°C (DIP-8) PD 1000
M mW
Power dissipation at Ta<25°C (SOP-8)
Operating Junction Temperature
PD
TJ U
460
-40~150
mW
°C
Storage temperature T STG
C -55~150 °C
Lead temperature (soldering, 10s) T LEAD
O 260，10s °C
Latch-up test per JEDEC 78 -
D 200 mA
ESD, HBM model per Mil-Std-883, Method 3015
ESD, MM model per JEDEC EIA/JESD22-A115

A LHBM
MM
2000
200
V
V

Recommended Operating Conditions T I

Table 2. Absolute Maximum Ratings

Oscillation frequency
Parameter

E N Symbol
f OSC
Min
50
Max
200
Unit
kHz
Operating temperature

I D Ta -40 85 °C

F
Table 3. Recommended Operating Conditions

N
O
C
C
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December, 2013 Rev. 1.2 5/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Electrical Characteristics (Ta=25°C, V CC =15.0V, RT=10kΩ, CT=3.3nF, unless otherwise specified)

Parameter Symbol Conditions Min Typ Max Unit
Reference Section
Reference output voltage
Line regulation
V REF
△V V
I REF =1mA
V CC =12V~25V
4.90
-
5.00
4
5.10
15
V
mV T
Load regulation
Short circuit output current
△V L
I SC
I REF =1mA~20mA
V REF =0V, Ta=25°C
-
-
4
-100
15
-180
E N mV
mA
Temperature stability △V T - - 0.2 0.4 mV/°C
Under -Voltage Lockout Section
M
Start threshold1
V ST
SDC3842/3844 15
U
16 17 V
Start threshold2
Min. operation voltage1
SDC3843/3845
SDC3842/3844
7.8
8.5 C 8.4
10
9.0
11.5
V
V
Min. operation voltage2
V OP
SDC3843/3845
O 7.0 7.6 8.2 V

Start-up current I ST
Total Standby Current Section
V CC =14V D - 0.15 0.30 mA
Operating supply current
Zener voltage
I OP
VZ I CC =25mA
A L
V FB =0, V CS =0, C L =1nF -
30
10
34
14
-
mA
V

Max. duty cycle1

D MAX T I
PWM Section
SDC3842/3843 95 97 100 %
Max. duty cycle2
Min. duty cycle D MIN

E N SDC3844/3845
-
Oscillator Section
46
-
48
-
50
0
%
%

Oscillation frequency
Oscillator amplitude
I D
f OSC
V OSC
T J =25°C
Pin RT/CT, peak to peak
47
-
52
1.7
57
-
kHz
V
Temperature stability
F △F T - - 2 - %
Voltage stability
Discharge current N △F V
I DIS
V CC =12V~25V
V RT /V CT =2V
-
8.5
0.2
-
1
10.5
%
mA

O Error Amplifier Section

Input voltage
Output sink current C VI
I SINK
V COMP =2.5V
V COMP =1.1V
2.45
2
2.50
6
2.55
-
V
mA

C
Output source current I SOURSE V COMP =5V -0.5 -0.8 - mA

S D
High output voltage
Low output voltage
Voltage gain
V OH
V OL
GV
R L =15kΩ to GND
R L =15kΩ to pin REF
V O =2V~ 4V
5
-
65
6
0.7
90
-
1.1
-
V
V
dB
Power supply rejection ratio PSRR V CC =12V~25V 60 70 - dB
Current Sense Section
Maximum input signal V IMAX V COMP =5V 0.9 1.0 1.1 V
Gain Gv V CS =0V~0.8V 2.85 3 3.35 V/V
Power supply rejection ratio PSRR V CC =12V~25V - 70 - dB
Delay to output tD V CS =0V~2V - 150 300 ns

December, 2013 Rev. 1.2 6/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Parameter Symbol Conditions Min Typ Max Unit

Input bias current I BIAS - - -3 -10 uA
Output Section
Low output voltage
Low output voltage
V OL
I SINK =20mA
I SINK =200mA
-
-
0.1
1.4
0.4
2.2
V
V T
High output voltage
High output voltage
V OH
I SOURSE =20mA
I SOURSE =200mA
13
12
14
13
-
-
E N V
V
Rise time tr T J =25°C, C L =1nF - 50 150 ns
Fall time tf T J =25°C, C L =1nF - 50
M 150 ns
Over-temperature Protect Section
U
Shutdown temperature
Temperature hysteresis
TS
T HYS
-
-
-
- C 155
25
-
-
°C
°C

O
Table 4. Electrical Characteristics
D
A L
T I
E N
I D
F
N
O
C
C
S D

December, 2013 Rev. 1.2 7/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Typical Application

AC IN+

T
AC IN- E N
Vo

M
U
C
O
VCC VREF

D
L
VFB RT/CT

COMP OUTPUT

GND CS
I A
SDC3842/384
T
3/3844/3845

E N
I D
F Figure 4. Typical Application

N
O
C
C
S D

December, 2013 Rev. 1.2 8/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Typical Performance Characteristics

DEADTIME(us) RT
30 100K

T
50K
10
CT=100nF
3

1
10K

5K
CT=10nF
CT=1nF

E N
0.3
0 2.2 4.7 10 22 47 100 CT(nF) 100 1K 10K
M
100K 1M fosc

Figure 5. Dead time vs. Timing capacitor

U
Figure 6. Timing resistor vs. Frequency

VREF(V) Temp(°C)
C
5.010
5.005
90
80 O
5.000
70
60 D VCC=15V,Ta=25°C

4.995
4.990
A L 50
40

4.985
4.980
T I 30
20
10
fosc(kHz)

-40 -20 0 20 40 60 80 100 120 Temp(°C)

Figure 7. Reference voltage vs. Temperature

E N 0
10 100 1K 10K 100K 1M

Figure 8. Error amplifier open-loop frequency response

I D
F
N
O
C
C
S D

December, 2013 Rev. 1.2 9/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

Package Dimension
DIP-8

T
E N
M
U
C
O
D
A L
T I
E N
I D
F
Symbol
N Dimensions In Millimeters
Min Max Min
Dimensions In Inches
Max
A
O 3.710 4.310 0.146 0.170
A1
A2 C 0.510
3.200 3.600
0.020
0.126 0.142
B
C 0.380 0.570 0.015 0.022

S D B1
C
D
0.204
9.000
1.524(BSC)
0.360
9.400
0.008
0.354
0.060(BSC)
0.014
0.370
E 6.200 6.600 0.244 0.260
E1 7.320 7.920 0.288 0.312
e 2.540(BSC) 0.100(BSC)
L 3.000 3.600 0.118 0.142
E2 8.400 9.000 0.331 0.354

December, 2013 Rev. 1.2 10/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

SOP-8

T
E N
M
U
C
O
D
A L
T I
E N
I D
F
N Dimensions In Millimeters Dimensions In Inches
Symbol
O Min Max Min Max
A
A1 C 1.350
0.100
1.750
0.250
0.053
0.004
0.069
0.010
A2
C 1.350 1.550 0.053 0.061

S D b
c
D
0.330
0.170
4.700
0.510
0.250
5.100
0.013
0.007
0.185
0.020
0.010
0.201
e 1.270(BSC) 0.050(BSC)
E 5.800 6.200 0.228 0.244
E1 3.800 4.000 0.150 0.157
L 0.400 1.270 0.016 0.050
θ 0° 8° 0° 8°

December, 2013 Rev. 1.2 11/12

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 Datasheet
Current Mode PWM Controller SDC3842/3843/3844/3845

T
E N
M
U
C
Shaoxing Devechip Microelectronics Co., Ltd.
O
http://www.sdc-semi.com/ D
L
UUUU UUUU

I A
T
E N
I D IMPORTANT NOTICE

F
Information in this document is provided solely in connection with Shaoxing Devechip Microelectronics Co., Ltd. (abbr. SDC) products.

N
SDC reserves the right to make changes, corrections, modifications or improvements, to this document, and the products and services
described herein at anytime, without notice. SDC does not assume any responsibility for use of any its products for any particular

O
purpose, nor does SDC assume any liability arising out of the application or use of any its products or circuits. SDC does not convey

C
any license under its patent rights or other rights nor the rights of others.
© 2013 Devechip Microelectronics - All rights reserved

Contact us: C
S D
Headquarters of Shaoxing

Address: Tian Mu Road, No13,

Shaoxing city, Zhejiang province, China

Shenzhen Branch

Address: 22A, Shangbu building, Nan Yuan Road, No.68,

Futian District, Shenzhen city, Guangdong province, China

Zip code: 312000 Zip code: 518031

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December, 2013 Rev. 1.2 12/12

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