TPS53915: MODE Pin usage and Floating of PMBUS signals

DEEPAK V14

Part Number: TPS53915

Hi,

Please find the attached schematic that generated using WEBENCH. The circuit is designed for 400KHz switching frequency with 12V input and the expected output is 1Volt at 8.5Amps.

Q1. Why is the MODE pin connected to VREG through 147K resistor? Is this connection right? Datasheet instruct us to connect MODE pin directly to VREG, then why 147K resistor is used in between?

Q2. What is the change that will happen if we connect MODE pin to PGOOD pin through 147K resistor, instead of connecting it to VREG pin?

Q3. Is it advisable to float all PMBUS signals such as SDA, SCL, ALERT, ADDR , if PMBUS functionality is not used ?

Thanks in advance
DEEPAK V

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

Q1. that is probably a Webench mistake. I'll get someone to look at this.
Q2. It is in the datasheet. If you connect mode to PGOOD the TPS53915 enters FCCM after PGOOD goes high.
Q3. Search is your friend. There are several other posts that state PMBus pins can be left open if not used.

0 DEEPAK V14 over 7 years ago in reply to JohnTucker

Intellectual 810 points

Hi John Tucker,

Thank you for the replaying within no time and resolving my doubts.

Please have a look to correct those Webench designs.

Thanks and regards
DEEPAK V

Power management

Power management forum

TPS53915: MODE Pin usage and Floating of PMBUS signals