4

LTC1772

1772fb

SWITCHING

LOGIC AND

BLANKING

CIRCUIT

–

+

0.5

µA

0.3V

0.3V

OVP

SHORT-CIRCUIT

DETECT

SHDN

1.2V

UV

1772 FD

+

60mV

0.8V

RS1

VOLTAGE

REFERENCE

SLOPE

COMP

ICMP

R

S

Q

FREQ

FOLDBACK

OSC

5

2

4

–

+

4

EAMP

–

+

3

PGATE

6

0.35V

0.8V

1

–

+

SHDN

CMP

GND

–

+

UNDERVOLTAGE

LOCKOUT

0.15V

–

+

BURST

CMP

SLEEP

serves as the error amplifier compensation point as well as

the run control input. The current comparator threshold

increases with this control voltage. Nominal voltage range

for this pin is 0.7V to 1.9V. Forcing this pin below 0.35V

causes the device to be shut down. In shutdown all

functions are disabled and the PGATE pin is held high.

GND (Pin 2): Ground Pin.

nal resistive divider across the output.

parator.

Pin 2.

PGATE (Pin 6): Gate Drive for the External P-Channel