1

LT1641

1641fd

Positive High Voltage

Hot Swap Controller

The LT

a board to be safely inserted and removed from a live

backplane. Using an external N-channel pass transistor,

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

mable rate. A high side switch driver controls an N-channel

gate for supply voltages ranging from 9V to 80V.

The chip features a programmable analog foldback cur-

rent limit circuit. If the chip remains in current limit for

more than a programmable time, the N-channel pass

transistor turns off and is optionally set to automatically

restart after a time-out delay.

The PWRGD output indicates when the output voltage,

sensed by the FB pin, is within tolerance. The ON pin

provides programmable undervoltage lockout.

The LT1641-1/LT1641-2 are recommended for new

designs.

The LT1641 is available in the 8-lead SO package.

Live Backplane

TIMER

SENSE

GATE

D1

CMPZ

5248B

GND

PWRGD

PWRGD

FB

R5

10

Ω

5%

ON

R1

49.9k

1%

*SMAT70A

*DIODES, INC.

24V

SHORT

PIN

GND

1641 TA01

R2

3.4k

1%

C2

0.68

µF

0.01

Ω

10nF

R3

59k

1%

R4

3.57k

1%

R7

24k

5%

LT1641

Q1

IRF530

24V Input Voltage Automatic Restart Application

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

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