[SOLVED] Physical ideal diode 80A (redundant power supplies)

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gmarocco

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The circuit employs the controller LTC4357 and two N-channel MOSFET IPB011N04L G . The MOSFETs are in parallel and the gate terminals are connected to the "GATE" terminal of the controller with two 10 Ohm resistors. Applying a load of 13A the difference between input and output is 0.03V while with a current of 40A the difference between input and output voltage is 0.22V while in theory it should be about 0.0011*40. Are the resistors in series with the gate terminals responsible for this behaviour? Lowering the resistors values can help in lowering the difference between the input and output voltage?View attachment ideal diode_schematics.pdf
 

Are the resistors in series with the gate terminals responsible for this behaviour?

Basically not. But instead of guessing, did you measure Vgs in on-state?
 

When one is working with 1,1 miliohm mosfets, the usual parasitic resistances that one usually disregards (i.e. solder joints, PWB traces, connectors) are no longer negligible.
I would measure the voltage drop right at the Mosfet terminals, to determine whether the loss is there or somewhere else.

Also, ensure that the Mosfet is fully enhanced. I've not read the datasheet, but please read it and determine what Vgs is required to achieve the specified RDSon. Then as FvM suggests, measure Vgs to see if you are meeting that requirement.
 
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