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TPS3435-Q1: Latching issue

Willem Zwetsloot
Prodigy 30 points
Part Number: TPS3435-Q1
Other Parts Discussed in Thread: TPS3430, TPS3435

Tool/software:

Hi TI,

I've been developing a system to be latched using an external open drain buffer based on the application note: snva837.

In this document, the implementation is based on the TPS3430, but my own judgement decided that the implementation of both the TPS3435-Q1 and TPS3430 are similar.

Im using the TPS3435AFACADDFRQ1

While testing I haven't found the latching functionality working at all.

I'm using the next values for my components:

- Crst = 2.2nF.

- Cwd = 10nF.

- 10k pull-up resistor after WDO*.

- SET0 = 0.

- VDD = 3V3.

When testing I find that the capacitor is just charged by the Crst pin, but in my understanding when asserted the open drain buffer SN74LVC1G07DBVR should keep Crst from being charged which latches the whole system.

Do you have any suggestions as to why this latching functionality isn't working?

Kind Regards,

Max

  • 0
    TI__Genius 9045 points

    Hello Max,

    TPS3430 device charges and discharges the respective capacitance for every watchdog frame or error event. 

    The TPS3435 device does not charge and discharge the capacitance for every time. The capacitance value is detected during power up and the timer values are defined based on the detected capacitance.

    Hence the implementation described in SNVA837 to keep the CRST pin low will not work for TPS3435. We do offer latched output configuration for TPS3435 device with fixed timing options in C pinout.

    We plan to release following options with latched output capability in near future. Do let us know if any of these options can meet your timing requirements.

    TPS3435CAEBJDDFR

    TPS3435CAGBJDDFRQ1

    TPS3435CBHAJDDSR

    TPS3435CCGAJDDFR

    TPS3435CECAJDDFRQ1

    TPS3435JAJAJDSER

    TPS35DA40GCJDDFR

    Thanks & Regards,

    Shridhar.

  • 0 in reply to Shridhar%20More
    Prodigy 30 points

    Hi Shridhar,

    Thank you for the information.

    The issue is quite urgent so we're searching for a solution asap. When will these chips be available?

    As these chips may not be available as soon as we need them, do you have a recommended circuit to latch the output?

    I hope to hear from you soon.

    Kind regards,

    Max Overvoorde

  • 0 in reply to Willem Zwetsloot
    TI__Genius 9045 points

    Hello Max,

    Below orderable will release to market in October 2024.

    TPS3435CAEBJDDFR

    TPS3435CAGBJDDFRQ1

    TPS3435CBHAJDDFR

    TPS3435CCGAJDDFR

    TPS3435CECAJDDFRQ1

    TPS35DA40GCJDDFR

    If you need samples for evaluation now, we can support samples (up to 10 units) of any one OPN. Please contact your local TI support to raise a request for samples.

    Thanks & Regards,

    Shridhar