1

LT1640AL/LT1640AH

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

Allows 50mA of Reverse Drain Pin Current

s

Programmable Electronic Circuit Breaker

s

Programmable Overvoltage Protection

s

Programmable Undervoltage Lockout

s

Power Good Control Output

The LT

Hot Swap

inserted and removed from a live backplane. Inrush cur-

rent 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 (LT1640AL) or PWRGD (LT1640AH) signal can

be used to directly enable a power module. The LT1640AL

is designed for modules with a low enable input and the

LT1640AH for modules with a high enable input.

The LT1640AL/LT1640AH are 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

CONTACT

BOUNCE

1640A F07b

LT1640AL

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%

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

1640A TA01

+

TRIM

–

–

ON/OFF

LUCENT

JW050A1-E

+

2

9

5V

8

7

6

5

1

4

+

C5

100

µF

16V

+

4

3

2

1

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO