5

LT1304/LT1304-3.3/LT1304-5

I

DAGRA

BLOCK

S

–

+

1304 F02

–

+

–

+

1.17V

R1

36mV

A3

OFF

LBI

SENSE

ENABLE

A2

LB0

SW

GND

SHDN

A1

8

6

5

4

3

7

1

1.5V

UNDERVOLTAGE

LOCKOUT

Q3

Q2

×1

Q1

×200

R2

1k

590k

R1

7.2

Ω

1k

DRIVER

BIAS

~1V

2

1.24V

SHUTDOWN

TIMERS

6

µs ON

1.5

µs OFF

R1 = 355k (LT1304-3.3), 195k (LT1304-5)

Figure 2. LT1304-3.3/LT1304-5 Block Diagram

–

+

1304 F01

–

+

–

+

1.17V

R4

36mV

A3

OFF

LBI

ENABLE

A2

LB0

C1

L1

SW

GND

SHDN

FB

A1

8

6

5

4

3

7

1

1.5V

UNDERVOLTAGE

LOCKOUT

Q3

Q2

×1

Q1

×200

R2

1k

R3

R1

7.2

Ω

1k

DRIVER

BIAS

~1V

2

1.24V

SHUTDOWN

+

C2

D1

+

TIMERS

6

µs ON

1.5

µs OFF

Figure 1. LT1304 Block Diagram. Independent Low-Battery Detector A3 Remains Alive When Device Is in Shutdown