LM5050-1: VGS is zero

Laker Lian

Part Number: LM5050-1

Hello;

I tested LM5050-1 at light load mode,VGS only 1.7V ,

When the load 2A or 3A...,The voltage of VGS is zero and the current flows through D2,

I wonder if the output has no capacitance or what's the problem?

TKS!

0 Karikalan Selvaraj over 5 years ago

At no load or light load, Vgs can be low, actually close Vth of the MOSFET used.

Vgs will increase as the load current is increased.

Can you share the schematic used?

I could not refer to the diode D2 you mention.

Regards,

Kari.

0 Laker Lian over 5 years ago in reply to Karikalan Selvaraj

Hello Kari:

D2 is parallel to MOSFET, I wonder if the output has no capacitance?

TKS!

0 Karikalan Selvaraj over 5 years ago in reply to Laker Lian

When 2A is taken from VIN side, Vgs should not be 0V.

Can you share some waveforms showing Gate, IN and OUT and current?

Can you please check if the MOSFET is not damaged.

Regards,

Kari.

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