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LT4250 Hot Swap power shor circuit test


We design a custom board. We use LT4250 as hot swap power controller. I attach the schematic of my design.

We use 48V and 35A as power supply.

We use 2mR (CSNL1206FT2L00) resistor as R1069 (Sense resistor) and use IRF3710STRLPBF as Q9 transistor then  We apply the short circuit test to the hotswap power by shorting the C52 capacitor.

When we power on the supply, after some Milliseconds the Drain-Source of Q9 short and the hot swap controller do not protect the board.

The Current - Continuous Drain (Id) @ 25°C of Q9 is 57A and the maximum current of R1069 is 23A. I do not have any idea about this failure.

What can i do to understand this failure? 


attach the schematic file.
[edited by: mohsenhaghighat70 at 11:31 AM (GMT 0) on 14 Oct 2019]
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  • HI ,

    You can add the automatic restart circuit as shown below. The behavior of the circuit is as follows:

    Before any short circuit etc , GATE pin is high and Q3 is turned on , pulling node 2 to VEE. Resistor R8 turns off Q2. After a short occurs, the GATE pin is pulled low and Q3 turns off. Node 2 starts to charge C4 and Q2 turns on , pulling UV pin low and resetting the circuit breaker. As soon as C4 is fully charged, R8 turns off Q2, UV goes high and gate starts to ramp back up. Q3 turns on and pulls node 2 back to VEE. D1 clamps node 3 one diode drop below VEE. The duty cycle is set to 10% to avoid Q1 overheating.

    Let me know if you have any concerns.