OPA548: Current limited at 0.65A

Eddie Koh

Genius 10505 points

Part Number: OPA548

Customer using OPA548.

V+ / V- = +/-28V

Ilim tied to V- to ensure limit set at 5A

Driving a 10 Ohm resistor, we can only get 6.52V. What is limiting the current output?

I have schematics to share via email.

over 4 years ago

0 kai klaas69 over 4 years ago

Guru 140200 points

Hi Eddie,

driving a 10R resistor with a voltage drop of 6.52V means a load current of 0.652A. This results in a heat dissipation of OPA548 of (28V - 6.52V) x 0.652A = 14W. That's quite a lot. So, I think that OPA548 goes into thermal shutdown. What says the E/S pin?

Have you mounted a heat sink? Please read section 10.1 of datasheet.

Kai

0 Raymond Zhang1 over 4 years ago in reply to kai klaas69

TI__Mastermind 47996 points

Hi Eddie,

In addition to Kai's comments, enclosed is the max. power dissipation vs. ambient temperature shown in the datasheet.

Best,

Raymond

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OPA548: Current limited at 0.65A