UC2844: Soft-start Transistor

Hirotsugu Kobayashi

Mastermind 9540 points

Part Number: UC2844

Tool/software:

Hi team,

What transistor is recommended for use in soft start?

Can the 2907A be used?

1 month ago

0 Adhvaidh Aravind 1 month ago

TI__Intellectual 810 points

Hi,

Thanks for reaching out. Please give me till end of tomorrow. I will get back to you with a recommendation.

Thank you for your patience.

Best,

Adhvaidh

0 Adhvaidh Aravind 1 month ago

TI__Intellectual 810 points

Hi,

Yes, MPS2907A transistor can be used as it meets all the specifications.

Thank you for your patience!

Best,

Adhvaidh

0 Hirotsugu Kobayashi 1 month ago in reply to Adhvaidh Aravind

Mastermind 9540 points

Hi Adhvaidh,

Thanks, but would it not exceed the maximum Vbe rating?

Best regards,

0 Adhvaidh Aravind 1 month ago in reply to Hirotsugu Kobayashi

TI__Intellectual 810 points

Hi,

The range of emitter voltage (COMP) is 5 to 6 V, and the Base voltage range (VREF) is 4.95 to 5.1 V. In that case, VBE (max) will be 1.05 V, which is within the specs of 2907A. On top of that, there will be some drop across the resistor RSS, so it should be fine!

Thank you.

Best regards,

Adhvaidh

Power management

Power management forum

UC2844: Soft-start Transistor