Contek UC3843A, UC3842A Datasheet
UC3842A / 3843A LINEARINTEGRATED CIRCUIT
CURRENT MODE PWM CONTROL
CIRCUITS
DESCRIPTION
The Contek UC3842A/3843A provide the necessary functions
to implement off-line or DC to DC fixed frequency current
mode , controlled switching circuits with a minimal external
part count
FEATURES
*Low external part count.
*Low start up current ( Typical 0.12mA )
*Automatic feed forward compensation
*Pulse-by-Pulse current limiting
*Under-voltage lockout with hysteresis
*Double pulse Suppression
*High current totem pole output to drive MOSFET directly
*Internally trimmed band gap reference
*500kHz operation
BLOCK DIAGRAM
Vref
VFB
COMP
CURRENT SENSE
RT/CT
8
2
1
3
4
Contek
Internal
Bias
1/2Vref
ERROR
AMPLIFIER
5V REF S/R
Vref
Good
Logic
1/3Vref
OSCILLATOR
1V
CURRENT
SENSE
COMPARATOR
U.V.L.O
R
PWM
LATCH
S
7
5
7
6
5
SOP-8
DIP-8
Vcc
GND
Vcc
OUTPUT
GND
ABSOLUTE MAXIMUM RATINGS(Ta=25 C)
PARAMETER SYMBOL VALUE UNIT
Supply Voltage(Low Impedance Source) VCC 30 V
Supply Voltage(Icc<30mA) Vcc Self Limiting V
Output Current ( Peak ) Io +-1 A
Output Energy(capacity Load) 5 mJ
Analog Inputs(pin 2,3) VI(ANA) -0.3 ~ +6.3 V
Error Amplifier Output Sink Current ISINK(EA) 10 mA
Power Dissipation PD DIP-8 at Tamb<=25 C 1.0 W
SOP-8 at Tamb <=25 C 0.5 W
Lead Temperature( Soldering 10 Sec ) Tlead 300 C
Contek Microelectronics Co.,Ltd.
CONTEK
http://www.contek-ic.com E-mail:sales@contek-ic.com
1
UC3842A / 3843A LINEARINTEGRATED CIRCUIT
(continued)
PARAMETRER SYMBOL VALUE UNIT
Storage Temperature Tstg -65 ~ +150 C
Note 1: Ta>25 C, PD derated with 8mW/ C.
ELECTRICAL CHARACTERISTICS(0 C <=Ta<=70 C,VCC=15V,RT=10kW,CT=3.3nF,unless otherwise
specified)
Reference Section
Output Voltage VREF
Line Regulation
Load Regulation
Temperature Stability (Note 2) 0.2 0.4
Total Output Variation Line, Load, Temp(note 2) 4.82 5.18 V
Output Noise Voltage Vosc
Long Term Stability
Output Short Circuit ISC -30 -100 -180 mA
Oscillator Section
Initial Accuracy f
Voltage Stability
Temperature Stability Tmin<=TA<=Tmax(note 2) 5 %
Amplitude Vosc Vpin 4 peak to peak 1.7 V
Error Amplifier Section
Input Voltage VI(EA) Vpin 1=2.5V 2.42 2.50 2.58 V
Input Bias Current IBIAS -0.3 -2
AVOL 2 <=Vo<=4V 60 90 dB
Unity Gain Bandwidth
PSRR I2<=Vcc<=25V 60 70 dB
Output Sink Current Isink Vpin 2=2.7V,Vpin 1=1.1V 2 6 mA
Output Source Current Isource Vpin 2=2.3V,Vpin 1=5V -0.5 -0.8 mA
Vout High VOH
Vout Low VOL Vpin 2=2.7V,Vpin 1=1.1V 0.7 1.1 V
Current Sense section
Gain GV (note 3,4) 2.85 3 3.15 V/V
Maximum Input signal VI(MAX) Vpin 1=5V( note 3) 0.9 1 1.1 V
PSRR 12<=Vcc<=25V 70 dB
Input Bias Current IBIAS -2 -10
Delay to Output Vpin 3=0 to 2V 150 300 ns
Output Section
Output Low Level VOL Isink=20mA 0.1 0.4 V
Output High Level VOH Isource=20mA 13 13.5 V
Rise Time tR
Fall Time tF
Under-Voltage Lockout Output Section
Start Threshold VTH(ST) Contek 3842A 14.5 16 17.5 V
Min. Operating Voltage VOPR(min) After Turn On
PWM Section
Maximum Duty Cycle D(MAX) 95 97 100 %
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
4.9 5 5.1 V
mV/ C
50 uV
525mV
47 52 57 kHz
mA
0.7 1 MHz
56 V
mA
50 150 ns
50 150 ns
8.5 10 11.5
DV
REF
DV
REF
Df/DVcc
Tj=25 C,Io=1mA
12<=VIN<=25V 6 20 mV
1<=Io=20mA 6 25 mV
10Hz<=f<=10kHz,Tj=25 C (note 2)
Ta=25 C,1000Hrs(note 2)
Tj=25 C
12<=Vcc<=25V 0.2 1 %
Tj=25 C (note 2)
Vpin 2=2.3V, RL=15kW to GND
Isink=200mA 1.5 2.2 V
Isource=200mA 12 13.5 V
Tj=25 C,CL=1nF(note 2)
Tj=25 C,CL=1nF(note 2)
Contek 3843A 7.8 8.4 9 V
Contek 3842A
Contek 3843A 7 7.6 8.2 V
CONTEK
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
2
Loading...