CURRENT MODE PWM CONTROL CIRCUITS
UTC UC3842A / 3843A LINEAR INTEGRATED CIRCUIT
CURRENT MODE PWM CONTROL CIRCUITS
DESCRIPTION
The UTC UC3842A/3843A provid...
Description
UTC UC3842A / 3843A LINEAR INTEGRATED CIRCUIT
CURRENT MODE PWM CONTROL CIRCUITS
DESCRIPTION
The UTC 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
SOP-8
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
DIP-8
BLOCK DIAGRAM
7
Vcc
Vref
8
Internal Bias 1/2Vref
5V REF
S/R
5 GND
Vref Good Logic 1/3Vref U.V.L.O CURRENT SENSE COMPARATOR R PWM LATCH S
7
Vcc
VFB COMP
2 1
ERROR AMPLIFIER
1V
6
OUTPUT
CURRENT SENSE 3
RT/CT
4
OSCILLATOR
5 GND
ABSOLUTE MAXIMUM RATINGS(Ta=25°C)
PARAMETER
Supply Voltage(Low Impedance Source) Supply Voltage(Icc<30mA) Output Current ( Peak ) Output Energy(capacity Load) Analog Inputs(pin 2,3) Error Amplifier Output Sink Current Power Dissipation Lead Temperature( Soldering 10 Sec )
SYMBOL
VCC Vcc Io VI(ANA) ISINK(EA) PD DIP-8 SOP-8 Tlead
VALUE
30 Self Limiting +-1 5 -0.3 ~ +6.3 10 at Tamb<=25°C 1.0 at Tamb<=25°C 0.5 300
UNIT
V V A µJ V mA W W °C
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
QW-R103-002,A
UTC UC3842A / 3843A LINEAR INTEGRATED CIRCUIT
(continued)
PARAMETRER
Storage Temperature Note 1: Ta>25°C, PD derated with 8mW/°C.
SYMBOL
Ts...
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