UC3842A 查看數據表（PDF） - Contek Microelectronics

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UC3842A

CURRENT MODE PWM CONTROL CIRCUITS

Contek Microelectronics 

UC3842A /3843A LINEARINTEGRATED CIRCUIT

PARAMETER

Minimum Duty Cycle

Total Standby Current

SYMBOL

D(MIN)

TEST CONDITIONS

MIN TYP MAX UNIT

0

%

Start-up Current

Operating Supply Current

IST

ICC(opr)

Vpin 2=Vpin 3=0V

Vcc Zener Voltage

Vz

Icc=25mA

note 2:These parameters, although guaranteed ,are not 100% tested in production.

note 3:Parameters measured at trip point of latch with Vpin 2=0.

note 4:Gain defined as:

DVpin 1

A=

; 0<=Vpin3<=0.8V

DVpin 3

note 5:Adjust Vcc above the start threshold before setting at 15V.

0.12 0.3 mA

11

17 mA

34

V

OPEN-LOOP LABORATORY TEST FIXTURE

Error Amp

Adjust

RT

1

8

2

7

Contek

3

6

5kW

4

5

CT

A

1kW

/ 1W

Vref

Vcc

OUTPUT

High peak current associated with capacity loads necessitate careful grounding techniques. Timing and bypass

capacitors should be connected close to pin 5 in single point GND. The transistor and 5kW potentio-meter are used to

sample the oscillator waveform and apply an adjustable Ramp to Pin 3.

UNDER-VOLTAGE LOCKOUT

Vcc

7

ON/OFF Command

to rest of IC

Icc

>15mA

Von=16V

Voff=10V

<1mA

Von

Voff

Vcc

During Under-Voltage Lockout, the output driver is biased to a high impedance state. Pin 6 should be shunt to

GND with a bleeder resistor to prevent activating the power switch with output leakage currents.

Contek Microelectronics Co.,Ltd.

3

CONTEK

http://www.contek-ic.com E-mail:sales@contek-ic.com

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