LT4239

1

Rev. 0

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TYPICAL APPLICATION

FEATURES

DESCRIPTION

High Current Hot Swap Controller

with Current Monitor Output

The LT®4239 hot swap controller allows a board to be

safely inserted and removed from a live backplane. Using

external N-channel pass transistors, board supply voltage

and inrush current are ramped up at a controlled rate. Dual

12V gate drive supports high current loads by providing a

two-stage start-up that first charges the load capacitance

followed by enabling a low on-resistance path to the load.

The supply output is protected against short-circuit faults

with a fast-acting electronic circuit breaker.

By placing the sense resistor on the output side and an RC

filter at the device’s supply pin, the MOSFET avalanching

can suppress the surge voltage when it is abruptly turned

off without the additional TVS at the board supply input.

The LT4239 features a current monitor that amplifies the

voltage across an external sense resistor. It also provides

undervoltage protection, and reports fault and power

good status for the supply. A boost mode allows the cir-

cuit breaker and current limit thresholds to be raised to

ride through load surges without generating a fault.

12V, 100A Application

APPLICATIONS

n

Allows Safe Board Insertion into Live Backplane

n

Wide Operating Voltage Range: 4V to 20V

n

Dual Gate Drivers for High Current Applications

n

Withstands Surge Voltage without Protection TVS

n

n

Accurate 10mV ± 5% Circuit Breaker Threshold

n

Boost Mode for Load Surges

n

Current Monitor Output

n

n

Adjustable Start-Up and Overcurrent Fault Delay

n

Input Undervoltage Protection

n

Fault and Power Good Output

n

16-Lead 4mm × 3mm DFN Package

n

Electronic Circuit Breaker

n

Enterprise Servers and Data Storage Systems

n

Network Routers and Switches

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Start-Up Waveforms

START-UP FET

BYPASS FET

100k

1µF

10m

0.16m

33nF

1k

2.2µF

2k

10

10

1k

13.7k

10mF

SENSE1 SENSE2

GATE1

DRAIN

STMR

UV

CBTMR

OUT

OUTK

GATE2

PG

FLT

LT4239

GND

IBOOST

IMON

12V

12V

100A

1

1

0.16m

1

1

10

BYPASS FET

+

47nF

4239 TA01a

ADC

20ms/DIV

PG

10V/DIV

4239 TA01b

10V/DIV

10V/DIV

10V/DIV