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CSD97376Q4M: CSD97376Q4M

AMIR SALHUV
Prodigy 45 points
Part Number: CSD97376Q4M

Hi, 

We are working with this IC for already ~5 years. we are using full bridge topology with two of the IC driving a wireless charging coil. in our new design, the input voltage is 24V (was 19V before). Our Vdd is 5V (that being created from a DC-DC 24V input. buck converter. our SKIP# is 3.3V that being created from a 5V input buck (the same as the Vdd).

In our former design everything worked well, but now we see that sometimes that Driver will not start to work even when we invoke frequency and SKIP# is high (3.3V). We think that it might be related to the reason that our SKIP# is 3.3V that rises couple of uS after the 5V (Vdd), where in our former design the 5V was both the Vdd and SKIP# voltage. We think that this is might be related to your note:

We see that sometimes our Vdd voltage rises to ~2.5V before the 3.3V enable rises, so it might be that issue. 

our uP connected only to the two PWM. we do not have any control over the enable (connected to pull-up). 

I have 2 questions for that:

1. We are already in DV phase (already produce 400pcs), is there any way that we can turn the drivers on ? doing something with the PWM ? 

2. For back up plan, we would like to connect the SKIP# to our uP with a Pull down of 50K ohms, and set the SKIP# to 3.3V after uP turns on. Do you see any problem with that ?

This issue is  urgent, so I will happy if you can assist us ASAP

Thanks 

Amir 

  • 0
    TI__Mastermind 18200 points

    Amir,

    Thanks for posting! It sounds like you have pegged your problem with respect to powering up the device with SKIP# in the tristate. 

    I do believe your back up solution tying SKIP# to the uP should work but let me confer with our team of experts to see if they have any other recommendations with respect to your first question and confirm the second. 

    Hopefully I can get back to you with some feedback on Monday at the latest. 

  • 0 in reply to Brett Barr1
    TI__Mastermind 18200 points
    Amir,
    See the response from our apps engineers below.

    1. We are already in DV phase (already produce 400pcs), is there any way that we can turn the drivers on ? doing something with the PWM ?

    After the driver enters low power mode, the way to get out of it is to pull SKIP# low for certain time(>~50us) then pull high.

    2. For back up plan, we would like to connect the SKIP# to our uP with a Pull down of 50K ohms, and set the SKIP# to 3.3V after uP turns on. Do you see any problem with that ?

    Please just make sure that the slew rate for SKIP# to change from low to 3.3V is fast enough so that SKIP# will not stay in tri-state window for time longer than Tri-state activation time.

    Hopefully this answers all your questions but if there is anything else, please feel free to reopen this thread and let me know.