TPS548A20: FCCM Mode selection

JH Shin

Guru 11650 points

Part Number: TPS548A20

Hello,

My customer designed the TPS548A20 as below for FCCM mode selection and connecting the PGOOD pin to a 3.3V device.

Are there any problems with the design?

Thank you.

over 4 years ago

0 David_Daniels over 4 years ago

TI__Mastermind 25665 points

See the Link to FAQ regarding the FCCM Mode selection for pullup voltages other than VREG voltage level

0 JH Shin over 4 years ago in reply to David_Daniels

Guru 11650 points

Hi David,

Thanks for your reply.

My customer wants a clearer guide to the above circuit.

1. Does the 105k and 200k pull-up/down resistor the customer used for the PGOOD 3.3V affect the FCCM mode selection?

2. Conversely, does the 150K resistor used for FCCM mode selection affect the use of PGOOD 3.3V?

Regards,

0 David_Daniels over 4 years ago in reply to JH Shin

TI__Mastermind 25665 points

1. Link to FAQ the voltage needs to be greater than 2.5V on MODE pin to enter FCCM.

2. No it should not. The 100k and 200k to level shift voltage can be changed to lower values, if the leakage currents to PGOOD pin or the SN74xx device input are higher than typical or VREG voltage lower than typical. The voltage on mode needs to be greater than 2.5V to enter to FCCM

Power management

Power management forum

TPS548A20: FCCM Mode selection