Philips Semiconductors Linear Products

Product specification

UC3842

Current-mode PWM controller

August 31, 1994

1103

DC AND AC ELECTRICAL CHARACTERISTICS

0

SYMBOL

PARAMETER

TEST CONDITIONS

UC3842

UNIT

SYMBOL

PARAMETER

TEST CONDITIONS

Min

Typ

Max

UNIT

Output section

Output Low-Level

0.1

0.4

V

Output Low-Level

1.5

2.2

V

Output High-Level

13

13.5

V

Output High-Level

12

13.5

V

Rise time

50

150

ns

Fall time

50

150

ns

Undervoltage lockout section

Start threshold

14.5

16

17.5

V

Min. operating voltage after turn on

8.5

10

11.5

V

PWM section

Maximum duty cycle

93

97

100

%

Minimum duty cycle

0

%

Total standby current

Start-up current

0.5

1

mA

Operating supply current

11

17

mA

34

V

Maximum operating frequency section

Maximum operating frequency for all

functions operating cycle-by-cycle

400

kHz

NOTES:

1. These parameters, although guaranteed, are not 100% tested in production.

3. Gain defined as:

A

+

DV

PIN 1

DV

PIN 3

; 0

v V

PIN 3

v 0.8V

UNDERVOLTAGE LOCKOUT

UC3842

16V

10V

NOTE:

During Undervoltage Lock-Out, the output driver is biased to a high

impedance state. Pin 6 should be shunted to ground with a bleeder

resistor to prevent activating the power switch with output leakage current.

7

VCC

ON/OFF COMMAND

TO REST OF IC

VCC

VOFF

VON

ICC

<15mA

<1mA

ERROR AMP CONFIGURATION

NOTE:

Error AMP can source or sink up to 0.5mA.

2.5V

0.5mA

2

1

COMP

VFB

ZI

+

–