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LT4356-3 Simulation Issue - Negative Output with PML current load

Category: Hardware
Product Number: LT4356-3

Hi Team,

I'm using LT Spice to perform the simulation and notice have some simulation issue.

  1. Connect the LT4356-3 circuit with PWL current load ->
    1. Observed duration of output current (IR3) follows the PWL input after MOSFET cutoff (should be fall to zero after cutoff).
    2. Observed Negative Vout
  2. Connect the LT4356-3 circuit with resistive load
    1. Observed current spike (22.8Apk), duration 576us before falling to 15.5A.

Attached the PDF for your reference. 

Any recommendation?

PDF

  • I believe everything is as expected. When the load current (an ideal current source) goes too high, the LT4356-3's GATE pin pulls all the way to GND in an attempt to turn-off the MOSFET. The current source then pulls the MOSFET's source below GND (which turns the MOSFET back on) to maintain current. As you already found, changing to a resistive load fixes this problem. Alternatively, when using a current source as a load, you can right click on the current source and check the "This is an active load" box. The observed overcurrent spike (with resistive load) happens during the time it takes for the GATE voltage to slew down.