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TLV70030 Bad output

Filipe Carvalho
Prodigy 20 points

Hi.

I'm having a huge issue with the TLV70030DBV part. The output of the device is around 2Vrms and with a huge ripple. We have assembled 10 parts and all the parts have the same behavior.

The input of the TLV70030DBV is a 3.7V lithium battery.
Both input and output of the TLV70030DBV have a 10uF bypass capacitor (LMK107BBJ106MAHT).

The TLV70030DBV is supplying an RF integrated circuit and a microcontroller.
The RF have 2 supplies, Analog and Digital. They are both supplied by the TLV70030DBV and both inputs have an 1uF capacitor (0603YD105KAT2A).
The microcontroller has 2 bypass capacitors; 100nF (GRM155R61A104KA01D) and 10uF (same as the TLV70030DBV input/outpu).

Here you can find the graphs of the output of the TLV70030DBV :

Can you please help me on this? We schedule to go for production this Friday and this is a blocker.
Thank you in advance.

Best Regards,
Filipe Carvalho

  • 0
    TI__Guru 55940 points

    Hi Filipe,

    Could you please share a scope shot of the input to the LDO?  Is there anything else on the same rail that could be jerking the battery around?

    Also, what is your typical load current?  Is it possible that your load could be current limiting the deceive?  Could your load be causing transients?

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Prodigy 20 points

    Hello, Ryan.

    The battery is only connected to the LDO pins 1 and 3. The input voltage of the LDO is very flat. The current at the input is around 4mA.

    The load is only a microcontroller and a RF integrated circuit. I'm not seing where it can be any transients.

    I'm sending the schematic in attachment. SV1 is used to charge the battery or to enable the device using a short between pin 2 and 3.

    Thanks in advance for your time.

    0434.bean 2.0.pdf

    Best Regards,

    Filipe Carvalho

  • 0 in reply to Filipe Carvalho
    TI__Guru 55940 points

    Hi Filipe,

    If you were to replace your load with an equivalent resistance, do you still generate the saw-tooth waveform?

    Very Respectfully,

    Ryan