UC2825: Shutdown and restart

user6300940

Part Number: UC2825

Hi,I have trouble in designing a half-bridge DCDC power supply, and the UC2825AMDWREP is used to drive the MOSFETs.

I want to know what all are the reasons for UC2825 shutdown and restart.

I set no load and the input voltage of 54V, when I turn on the auxiliary power supply, which provides 12V to UC2825, the UC2825 keeps shutting down and restarting. So can you tell me what problem will take the UC2825 shutdown? Thanks!

over 4 years ago

0 Sonal Singh over 4 years ago

TI__Expert 6080 points

Hello,

I would suggest checking the voltage at Pin9 ILIM/SD. If this voltage is above 1.4V then the controller will do this behavior because of the current limit shutdown.

Regards,

Sonal

0 user6300940 over 4 years ago in reply to Sonal Singh

Prodigy 30 points

Thanks for your suggestion! I have measured the waveform of Pin9 ILIM and Pin8 SOFTSTART, and the voltage of Pin9 is always about zero, but the voltage of Pin8 is up to 5V and then fall to zero over and over again. So is there any other reason for the UC2825 to shutdown?

0 Sonal Singh over 4 years ago in reply to user6300940

TI__Expert 6080 points

Hello,

From the datasheet the only reasons for such restart behavior should be the following:

1. Ilim/SD pin going above the IC shutdown threshold of 1.4V.

2. UVLO below the IC shutdown threshold.

May you please show some waveforms with the ILim, Vcc, Vout and Vref and schematic so I can understand the system behavior better.

Regards,

Sonal

0 Sonal Singh over 4 years ago in reply to Sonal Singh

TI__Expert 6080 points

Hello,

I have not heard back from you for quite a while now. Do you still have the same issue? may you share the waveforms requested in the previous thread.

Regards,

Sonal

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UC2825: Shutdown and restart