LM5148: external bias VCCX sequence

Sam Ting

Part Number: LM5148

Tool/software:

Team,

Are there any sequence requirements for the external bias VCCX? If the 5V supply comes after the output voltage is ready, is it okay to switchover automatically? Thanks!

Regards,
Sam Ting

26 days ago

+1 Timothy Hegarty 26 days ago

TI__Guru 73862 points

Hi Sam,

No problem if the 5V external supply is applied after VOUT is in regulation. The main concern is the external bias supply coming up before VIN is applied, as there is a diode path from VCC to VIN that can conduct.

Regards,

Tim

0 Sam Ting 26 days ago in reply to Timothy Hegarty

TI__Expert 3590 points

Tim,

Thanks! I see the description on datasheet. "If an external supply is connected to VCCX to power the LM5148, VIN must be greater than the external bias voltage during all conditions to avoid damage to the controller."

Regards,
Sam Ting

0 Timothy Hegarty 25 days ago in reply to Sam Ting

TI__Guru 73862 points

Thanks, Sam.

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LM5148: external bias VCCX sequence