LT1640H Просмотр технического описания (PDF) - Linear Technology

Номер в каталоге

Компоненты Описание

производитель

LT1640H

Negative Voltage Hot Swap Controller

Linear Technology 

LT1640L/LT1640H

APPLICATIONS INFORMATION

Under some conditions, a short circuit at the output can

cause the input supply to dip below the UV threshold,

resetting the circuit breaker immediately.

The LT1640 then cycles on and off repeatedly until the

short is removed. This can be minimized by adding a

deglitching delay to the UV pin with a capacitor from UV to

VEE. This capacitor forms an RC time constant with the

resistors at UV, allowing the input supply to recover before

the UV pin resets the circuit breaker.

A circuit that automatically resets the circuit breaker after

a current fault is shown in Figure 9.

Transistors Q2 and Q3 along with R7, R8, C4 and D1 form

a programmable one-shot circuit. Before a short occurs,

the GATE pin is pulled high and Q3 is turned on, pulling

node 2 to VEE. Resistor R8 turns off Q2. When a short

occurs, the GATE pin is pulled low and Q3 turns off. Node

2 starts to charge C4 and Q2 turns on, pulling the UV pin

low and resetting the circuit breaker. As soon as C4 is fully

charged, R8 turns off Q2, UV goes high and the GATE

starts to ramp up. Q3 turns back on and quickly pulls node

2 back to VEE. Diode D1 clamps node 3 one diode drop

below VEE. The duty cycle is set to 10% to prevent Q1 from

overheating.

(SHORT PIN)

GND

GND

R7

R6

R4

1M

562k 562k

5%

2

1% 1%

C4

1µF

100V

Q2

2N2222

3

*

Q3

ZVN3310

D1

1N4148

R8

510k

5%

– 48V

* DIODES INC. SMAT70A

R9

R5

10k 19.1k

1% 1%

3

UV

2

OV

VEE

4

SENSE

5

R1

3

0.02Ω

5%

4

1

2

8

VDD

LT1640L

GATE

6

1

PWRGD

+

DRAIN

7

1N4148

C3

100µF

100V

C1

150nF

25V

R2 R3

10Ω 18k C2

5% 5% 3.3nF

100V

Q1

IRF530

1640 F09a

NODE 2

50V/DIV

10

GATE

2V/DIV

1s/DIV

1640 F09b

Figure 9. Automatic Restart After Current Fault

1640lhfb

Share Link: