1

LTC1421/LTC1421-2.5

Hot Swap Controller

FEATURES

s

Allows Safe Board Insertion and Removal from a

Live Backplane

s

System Reset and Power Good Control Outputs

s

Programmable Electronic Circuit Breaker

s

User Programmable Supply Voltage Power-Up Rate

s

High Side Driver for Two External N-Channels

s

Controls Supply Voltages from 3V to 12V

s

Connection Inputs Detect Board Insertion or Removal

s

Undervoltage Lockout

s

Power-On Reset Input

s

Hot Board Insertion

s

Electronic Circuit Breaker

The LTC

that allow a board to be safely inserted and removed from a

live backplane. Using external N-channel pass transistors,

the board supply voltages can be ramped up at a program-

mable rate. Two high side switch drivers control the N-

channel gates for supply voltages ranging from 3V to 12V.

A programmable electronic circuit breaker protects against

shorts. Warning signals indicate that the circuit breaker

has tripped, a power failure has occurred or that the switch

drivers are turned off. The reset output can be used to

generate a system reset when the power cycles or a fault

occurs. The two connect inputs can be used with stag-

gered connector pins to indicate board insertion or re-

moval. The power-on reset input can be used to cycle the

board power or clear the circuit breaker.

The trip point of the ground sense comparator is set at

0.1V for LTC1421 and 2.5V for LTC1421-2.5.

The LTC1421/LTC1421-2.5 are available in 24-pin SO and

SSOP packages.

10

9

14

13

8

11

15

6

7

RAMP

CPON

REF

FB

COMPOUT

PWRGD

RESET

2

24

4

3

1

CON2

FAULT

POR

CON1

LTC1421

GND

DISABLE

16

C2

0.1

µF

C1

1

µF

R5

16k

5%

Q1

MTB50N06E

R1

0.005

Ω

17

18

19

20

21

22

5

12

23

R3

1k

D1

R6

20k

1%

C3

220

µF

R4

20k

5%

R7

7.15k

1%

Q2

1/2 Si4936DY

Q3

1/2 Si4936DY

C3

0.47

µF

R2

0.025

Ω

+

C5

220

µF

– 12V

1A

12V

1A

5V

5A

C4

220

µF

+

I/O

I/O

RESET

BEA

BEB

GND

1

13

12

µP

QS3384

QuickSwitch

®

QuickSwitch IS A REGISTERED TRADEMARK

OF QUALITY SEMICONDUCTOR CORPORATION.

1421 TA01

DATA BUS

PC BOARD

BACKPLANE

DATA

BUS

GND

POR

FAULT

1

µF

, LTC and LT are registered trademarks of Linear Technology Corporation.

Hot Swap is a trademark of Linear Technology Corporation.