TPS659038-Q1: Why can SMPS3_FDBK pin and SMPS7_FDBK pin be left floating when unused?

Shinsuke Tanaka

Intellectual 520 points

Part Number: TPS659038-Q1

Dear Sirs or Madams,

According to the datasheet shown on TI HP, Rev.K,

SMPS3_FDBK pin and SMPS7_FDBK pin should be left floating when unused

although all other feedback input pins such as SMPS9_FDBK pin has to be connected to GND when unused.

I'm wondering why there are such differences between SMPS3_FDBK/SMPS7_FDBK pins and other feedback input pins.

Could you please let me know the reason?

Even rough explanation, e.g. the internal structure of SMPS3 and SMPS7 are different from other SMPSs,

would be appreciated because the purpose of this question is just to confirm that

the above descriptions on SMPS3_FDBK/SMPS7_FDBK pins on the datasheet do NOT include typos or incorrect information.

Best regards,

Shinsuke Tanaka

over 5 years ago

0 Tuomo Alatalo over 5 years ago

TI__Intellectual 950 points

Hi Shinsuke,
Your question has been forwarded to responsible engineer and he/she will reply soon, thanks

Tuomo

0 Nastasha over 5 years ago

TI__Genius 10000 points

Hi,

SMPS3_FDBK and SMPS7_FDBK are the two rails that can be added to the dual phase rails for a triple phase configuration (SMPS123 and SMPS457). That is likely why these are marked differently in the datasheet. However, there is no issue grounding these rails if they are unused.

Thanks,
Nastasha

Power management

Power management forum

TPS659038-Q1: Why can SMPS3_FDBK pin and SMPS7_FDBK pin be left floating when unused?