UCC27424: Rbias of UCC27424 & UCC27712

user6244044

Part Number: UCC27424
Other Parts Discussed in Thread: UCC27712

Hi there,

I am curious about the usage of the bias resistor on UCC27424 & UCC27712.

According to the datasheet of UCC27712, the purpose of external bias resistor connected to VDD pin is limiting the slew rate when power supply comes up.

However, I am wondering why it needs no external bias resistor to VDD pin when using UCC27424?

Thank you!

over 4 years ago

0 Mamadou Diallo over 4 years ago

TI__Genius 13445 points

Hello,

Thanks for reaching out.

A series bias resistor (in addition to 2 decoupling caps directly across VDD pins) is good practice to limit inrush current on VDD supply pin for both UCC27424 and UCC27712.

Regards,

-Mamadou

0 user6244044 over 4 years ago in reply to Mamadou Diallo

Prodigy 120 points

Hi Mamadou,

Is it necessary to put 1 resistor and 2 decoupling caps for both ICs? I want to use the external discrete components as less as it can.

BTW, is there any Rbias selecting suggestion for UCC27424?

Thank you!

0 Mamadou Diallo over 4 years ago in reply to user6244044

TI__Genius 13445 points

Hello,

Yes it is absolutely necessary to have 2 parallel low ESL/ESR decoupling caps directly across VDD.

Rbias resistance is optional (but highly recommended 10-Ohms) depending on application expect dv/dt.

I hope this answers your inquiry.

Regards,

-Mamadou

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UCC27424: Rbias of UCC27424 & UCC27712