5

LTC1147-3.3

LTC1147-5/LTC1147L

sn1147 1147fds

to ground Pin 7.

the operating frequency. The actual frequency is also

dependent upon the input voltage.

comparator threshold increases with the Pin 3 voltage.

which sets the output voltage. Pin 4 is also the (–) input for

the current comparator.

A built-in offset between Pins 4 and 5 in conjunction with

versions of the LTC1147 family operate normally. Pulling

Pin 6 high holds the P-channel MOSFET off and puts the

LTC1147 in micropower shutdown mode. Requires CMOS

On the LTC1147L this pin serves as the feedback pin from

an external resistive divider used to set the output voltage.

GND (Pin 7): Two independent ground lines must be

PDRIVE (Pin 8): High current drive for the P-channel

Pin 6 Connection Shown For LTC1147-3.3 and LTC1147-5; Changes Create LTC1147L.

+

–

1

PDRIVE

GND

R

S

Q

C

25mV TO 150mV

3

13k

1.25V

6

REFERENCE

SHDN

V

G

5

6

100k

5pF

T

–

+

S

SLEEP

2

OFF-TIME

CONTROL

4

8

7

LTC1147 • FD

PI FU CTIO S

FU CTIO AL DIAGRA