5

LT1303/LT1303-5

GND (Pin 1): Signal Ground. Tie to PGND under the

package.

LBO (Pin 2): Open-Collector Output of Low-Battery Com-

parator. Can sink 100

µA. Disabled when device is in

shutdown.

SHDN (Pin 3): Shutdown. Pull high to shut down the

device. Ground for normal operation.

FB/Sense (Pin 4): On 1303 (adjustable) this pin connects

to the main comparator C1 input. On LT1303-5 this pin

connects to the resistor string that sets output voltage

at 5V.

LBI (Pin 5): Low-Battery Comparator Input. When voltage

on this pin below 1.24V, LBO is low.

value electrolytic to ground. Keep bypass within 0.2" of the

device.

SW (Pin 7): Switch Pin. Connect inductor and diode here.

Keep layout short and direct to minimize radio frequency

interference.

PGND (Pin 8): Power ground. Tie to signal ground (pin1)

tied directly to PGND within 0.2" of the device.

I

DAGRA

BLOCK

S

Figure 2. LT1303 Block Digram

–

+

–

+

6

7

8

3

2

5

1

4

+

+

C1

C2

L1

D1

R1

3

Ω

Q2

1

×

Q1

160

×

SHUTDOWN

LBO

LBI

GND

PGND

SW

R1

R2

C3

C2

C1

FB

OFF

OSCILLATOR

A3

DRIVER

CURRENT

COMPARATOR

HYSTERETIC

COMPARATOR

REFERENCE

1.24V

18mV

LT1303 BD01