Philips Semiconductors Linear Products

Product specification

UC3842

Current-mode PWM controller

August 31, 1994

1104

CURRENT SENSE CIRCUIT

NOTE:

Peak current (IS) is determined by the formula:

A small RC filter may be required to suppress switch transients.

I

S

MAX

+

1.0V

Rs

R

2R

1V

ERROR

AMP

CURRENT

SENSE

COMPARATOR

COMP

CURRENT

SENSE

GND

R

RS

IS

1

3

5

TYPICAL PERFORMANCE CHARACTERISTICS

Output Saturation Characteristics

Error Amplifier Open-Loop

Frequency Response

FREQUENCY (Hz)

100

80

60

40

20

0

–20

10

100

1k

10k

100k 1M

10M

45

0

–45

–90

–135

–180

–225

4

3

2

1

0

0.01

0.03 0.05 0.1

0.3 0.5

1.0

OUTPUT CURRENT, SOURCE OR SINK (A)

0

Av