1

LT1640L/LT1640H

1640lhfb

Negative Voltage

Hot Swap Controller

s

Allows Safe Board Insertion and Removal

from a Live – 48V Backplane

s

Operates from –10V to – 80V

s

Programmable Inrush Current

s

Programmable Electronic Circuit Breaker

s

Programmable Overvoltage Protection

s

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

(LT1640L) or PWRGD (LT1640H) 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.

s

Central Office Switching

s

– 48V Distributed Power Systems

s

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

1640 F06b

LT1640L

SENSE

C1

†

150nF

25V

C2

†

3.3nF

100V

C3

0.1

µF

100V

C4

100

µF

100V

Q1

IRF530

R2

10

Ω

5%

R3

†

18k

5%

1N4148

R4

†

562k

1%

R5

†

9.09k

1%

R6

†

10k

1%

R1

†

0.02

Ω

5%

4

OV

GND

GND

(SHORT PIN)

3

2

– 48V

OV = 71V

*

* DIODES INC. SMAT70A

SPECIFIC AND MUST BE SELECTED BASED

UPON OPERATING CONDITIONS AND DESIRED

PERFORMANCE. SEE APPLICATIONS

INFORMATION.

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

+

4

3

2

1

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

INRUSH

CURRENT

1A/DIV

10V/DIV

DRAIN

50V/DIV

50V/DIV

5ms/DIV

CONTACT

BOUNCE