5

LT1316

LBO (Pin 1): Low-Battery Detector Output. Open collector

can sink up to 500

µA. Low-battery detector remains active

in shutdown mode.

LBI (Pin 2): Low-Battery Detector Input. When voltage at

this pin drops below 1.17V, LBO goes low.

peak switch current. The resistor value should be between

3k and 150k. Do not float or short to ground. This is a high

impedance node. Keep traces at this pin as short as

possible. Do not put capacitance at this pin.

GND (Pin 4): Ground. Connect directly to ground plane.

SW (Pin 5): Collector of NPN Power Transistor. Keep

traces at this pin as short as possible.

pin.

SHDN (Pin 7): Shutdown. Ground this pin to place the part

in shutdown mode (only the low-battery detector remains

active). Tie to a voltage between 1.4V and 6V to enable the

device. SHDN pin is logic level and need only meet the

logic specification (1.4V for high, 0.4V for low).

FB (Pin 8): Feedback Pin. Reference voltage is 1.23V.

Connect resistive divider tap here. Minimize trace area at

–

+

1.17V

A3

LBI

A2

DRIVER

LB0

L1

R3 = 10R4

1.5V

UNDERVOLTAGE

LOCKOUT

D1

C1

R5

R4

0.5V

Q2

×1

R2

R1

Q1

×200

OSCILLATOR

6.3

µs ON

2

µs OFF

–

+

1.23V

FB

2

3

4

7

8

5

6

1

A4

SW

GND

1316 F01

SHDN

A1

Figure 1. LT1316 Block Diagram

BLOCK DIAGRA