• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 135 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TPS548D22: About the peripheral components of Pin37 RESV_TRK

TPS548D22: TPS548D22 pin 37

Nick Ancelin
Prodigy 10 points
Part Number: TPS548D22
Other Parts Discussed in Thread: TPS548D21

We have an existing design using TPS548D22 with pin 37 connected to gnd via a 1000pF cap.

This is a mature design and seems to have no issues, though I see from some of the posts

that pin 37 should be NC.

Due to supply constraints, can we replace TPS548D22 part with TPS548D21 part, all

else being the same ?  Pin 37 is connected 'ONLY' to gnd via 1000pF cap (and to nothing else).

The mode pin has a pullup resistor 100k 1% to pin 31 (BP) and a pulldown resistor of 42.7k 1% to gnd.

  • 0
    TI__Expert 5310 points

    Hi Nick,

    Leaving the 1000pF cap on pin 37 of the TPS548D21 is OK if using the part in place of the TPS548D22. I would be sure to make sure the connection to ground is direct and the routing from pin 37 to C270 is routed away from noisy lines on the board.

    In regards to the remainder of the design, the lower mode resistance of 42.7kohm is fine for an internal reference voltage, 1ms soft-start time. This selection will select the DCAP3 control mode supporting designs using only ceramic output capacitance as well. The TPS548D21 supports a wider range of mode options, but the 42.7 kohm will select the same setting as the design using the TPS548D22.

    With those considerations in mind, the TPS548D21 may work in place of the TPS548D22 without any significant BOM or schematic adjustments.

    Regards,

    Alec Biesterfeld