1

LT1640L/LT1640H

Negative Voltage

Hot Swap Controller

FEATURES

s

Allows Safe Board Insertion and Removal

from a Live – 48V Backplane

s

Operates from –10V to – 80V

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Programmable Inrush Current

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Programmable Electronic Circuit Breaker

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Programmable Overvoltage Protection

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Programmable Undervoltage Lockout

s

Power Good Control Output

The LT

Swap

and removed from a live backplane. Inrush current is

limited to a programmable value by controlling the gate

voltage of an external N-channel pass transistor. The pass

transistor is turned off if the input voltage is less than the

programmable undervoltage threshold or greater than the

overvoltage threshold. A programmable electronic circuit

breaker protects the system against shorts. The PWRGD

(LTC1640L) or PWRGD (LTC1640H) signal can be used to

directly enable a power module. The LT1640L is designed

for modules with a low enable input and the LT1640H for

modules with a high enable input.

The LT1640L/LT1640H is available in 8-pin PDIP and SO

packages.

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Central Office Switching

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– 48V Distributed Power Systems

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Negative Power Supply Control

Hot Swap is a trademark of Linear Technology Corporation.

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

Input Inrush Current

CONTACT

BOUNCE

1640 F07b

LT1640L

SENSE

C1

33nF

24V

C3

0.1

µF

100V

C4

100

µF

100V

Q1

IRF530

R2

10

Ω

5%

R3

10k

5%

C2

3.3nF

100V

R4

562k

1%

R5

9.09k

1%

R6

10k

1%

R1

0.02

Ω

5%

4

OV

GND

3

2

– 48V

OV = 71V

UV = 37V

UV

56

8

7

1

GATE

DRAIN

PWRGD

1640 TA01

+

TRIM

–

–

ON/OFF

LUCENT

JW050A1-E

+

2

9

5V

8

7

6

5

1

4

+

C5

100

µF

16V

+