• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 195 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:

TPS274160: Current sense output voltage levels

TPS274160: Possible change needed to TPS274160EVM

Mark Regina
Prodigy 130 points
Part Number: TPS274160

I'm getting ready to use the TPS274160EVM that I received today and in looking through the documentation, the circuitry used to set SEL and SEH on the TPS274160EVM doesn't seem quite right.  A screenshot taken from the PDF of the portion in question:

SEL and SEH circuitry on TPS274160EVM

The test points on the left can be jumpered to either GND or V_+5V in order to select which output's current sense signal gets put on CS.  This would apply either +5VDC or +2.5VDC to the input pins for SEH and/or SEL (ignoring the effect of the IC's internal pulldown on each pin) -- this seems to be not what is intended (should be +5VDC or GND).  I will be removing R13 and R17 before using the TPS274160EVM, since then the jumpers will be able to assert the SEH and SEL pins to the correct levels in order to set which output's current sense signal gets placed on CS.  The internal pulldowns have a specification of a minimum of 100kohm, so when driven high by jumper placement, 4.54V gets applied and when driven low by jumper placement, it properly goes down to GND.

  • 0
    TI__Mastermind 32650 points

    Hi Mark,

    The circuit will work for Version A device as these are ST pins that will be pulled up to 5V. In the case of Version B, the circuit will not allow for logic level low on the device.

    Please depopulate the resistors as necessary to pull this pin to GND. This modification is acceptable for the device.

    Thank you for your essential feedback.

    Shreyas

  • 0 in reply to Shreyas Dmello
    Prodigy 130 points

    Shreyas,

    The EVM does seem to be designed to handle both the TPS274160A and TPS274160B; however, mods do need to be made to the TPS274160EVM by the customer in order to get it to work properly with the B version -- the one that is on my board and the one that I hope to design in to a product, and I'm not sure what changes, if any, are necessary to work correctly with the A version.  In addition to removing R13 and R17, one other area needs a component removed in order to get an accurate current sense voltage:

    The 10k pullup to V_+5V on the CS/ST4_IC signal (R26) needs to be removed in order to get an accurate current sense voltage, otherwise 0.45V is on TP25 when the selected high side switch is OFF.  With R26 removed, I get a voltage on TP25 that corresponds to the current going through the selected switch.  Hopefully this information will help others who are using the EVM with a TPS274160B.