LTC4235

1

4235f

For more information www.linear.com/LTC4235

Typical applicaTion

FeaTures

DescripTion

Dual 12V Ideal Diode-OR

and Single Hot Swap Controller

with Current Monitor

functions for two 12V power rails by controlling external

N-channel MOSFETs. MOSFETs acting as ideal diodes

replace two high power Schottky diodes and the associ-

ated heat sinks, saving power and board area. A Hot Swap

control MOSFET allows a board to be safely inserted and

removed from a live backplane by limiting inrush current.

The supply output is also protected against short-circuit

faults with a foldback current limit and circuit breaker.

The LTC4235 regulates the forward voltage drop across

the MOSFETs to ensure smooth current transfer from one

supply to the other without oscillation. The ideal diodes

turn on quickly to reduce the load voltage droop during

supply switchover. If the input supply fails or is shorted,

a fast turn-off minimizes reverse-current transients.

A current sense amplifier translates the voltage across the

senseresistortoagroundreferencedsignal.TheLTC4235

allows turn-on/off control, and reports fault and power

good status for the supply.

applicaTions

n

Ideal Diode-OR and Inrush Current Control for

Redundant Supplies

n

Low Loss Replacement for Power Schottky Diodes

n

Enables Safe Board Insertion into a Live Backplane

n

9V to 14V Operation

n

Current Monitor Output

n

Controls N-Channel MOSFETs

n

Limits Peak Fault Current in ≤ 1µs

n

Adjustable Current Limit with Foldback

n

Adjustable Current Limit Fault Delay

n

0.5µs Ideal Diode Turn-On and Turn-Off Time

n

Smooth Switchover without Oscillation

n

Fault and Power Good Outputs

n

LTC4235-1: Latch Off After Fault

n

LTC4235-2: Automatic Retry After Fault

n

20-Pin 4mm x 5mm QFN Package

n

Redundant Power Supplies

n

High Availability Systems and Servers

n

Telecom and Network Infrastructure

L

, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot

Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of

their respective owners. Protected by U.S. Patents, including 7920013, 8022679.

Ideal Diode-OR with Hot Swap Application

12V

12V

CPO1

GND

ON

PWRGD

IMON

FAULT

13.7k

12V

7A

2k

D2OFF

IN1 DGATE1

DGATE2

LTC4235

4235 TA01a

SiR158DP

SiR158DP

0.003

HGATE OUT

CPO2

0.1µF

IN2

+

0.1µF

SiR158DP

EN

0.1µF

0.1µF

FTMR

REG

0.1µF

ADC

Smooth Supply Switchover

200ms/DIV

IN1

1V/DIV

IN2

1V/DIV

2A/DIV

2A/DIV

4235 TA01b

IN1

IN2