MP2276 question about VIN≤3.3V application?

DC-DC Power Converters
1

Dear support member,

My customer consider MP2276.

I have question.
Datasheet description is 『For VIN≤3.3V application, please connect VIN to VCC directly.』.

Q1
Why connect VIN and VCC when VIN is 3.3V or less?

Q2
If connect VIN and VCC don’t connect, is there a problem with operation?

Q3
The input voltage range is assumed to be 3.2V to 4.5V.
In that case, how should I connect?

Best regard.

2

Hello,
The Vcc function provides power to the control circuitry and the Vbst gate bias, so needs a minimum voltage for normal operation. The Vcc regulator has higher dropout so as Vin drops to 3V the Vcc voltage will drop well below that, disabling the operation. Connecting Vcc to Vin will override the dropout of that regulator and allow operation to 2.7V.

For 3.2V min operation, connect Vcc to Vin, that will work OK up to Vin=4.5V with no issues.
Regards,

3

Hi, James.P

Thank you very much for your answer.
May I have add a question?

Q4
The input voltage is in the range of 3.2V to 4.5V.
When VIN is 3.2V, connect VIN and VCC.
When VIN is 4.5V, disconnect VIN and VCC.
Is there a good circuit to switch like this?

Best regard.