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TPS60403: Alternative Part for TPS60403 for low noise low cost application

Gaurav Bhatia
Prodigy 60 points
Part Number: TPS60403
Other Parts Discussed in Thread: LM27762, , ADS1294, ADS1298, LM2776

Can someone help me find an alternative part for TPS60403 for using it along with ADS1294 (ECG FE ADC) application. I am not able to find TPS60403 on any of the distribution websites like DigiKey & Mouser. I need the regulator to be low cost and should need to have minimum passive components. I see the closest match to be LM27762 but that one too is not in stock anywhere.

I have a single cell Li-Ion as primary source i.e. Vin  max 4.7V and Vmin around 2.6V and I might need current out of around 60 mA based on ADS1298 EVK schematics. 

  • 0
    TI__Expert 3611 points

    Hi Gaurav,

    Unfortunately, we do not have another FPWM charge pump that would suit your application. There is the LM2776, however it has automatic power save mode for better efficiency at low loads - for low output noise FPWM is preferred in your application correct?

    Regards,
    Davor

  • 0 in reply to Davor Pavlovski
    Prodigy 60 points

    Yes, I need low noise LDO outputs to use it as VDD and VSS sources for my ADS1294 chip. Can you let me know if I have Li-Po battery as Vin to LM2776 and use dual output from LM2776 (+2.5V & -2.5V) then I won't be needing TPS73201 and TPS72301 LDOs as LM2776 has charge pump which is later fed to LDO to give a regulated output of -2.5V and it also has positive LDO for 2.5V.

    Can i use LM2776 for my application as it looks like better option in terms of lead times too.

    Are there any drawbacks of LM2776 compared to combined use of TPS60403, TPS73201 and TPS72301.

    ADS1298 EVK Schematics

    Thanks,

  • 0 in reply to Gaurav Bhatia
    TI__Expert 3611 points

    Hi Gaurav,

    Like I mentioned before, the LM2776 has an automatic power save mode which is described in Section 7.3.2 in the datasheet. You need to make sure that the ripple will be satisfactory by taking a look at Figure 1 in Section 6.7.

    Also a thing to keep in mind is that the LM2776 doesn't actually regulate the voltage to a set value, what it does is just invert the input voltage. This is well described in Section "8.2.2 Detailed Design Requirements" in the datasheet.

    Regards,
    Davor

  • +1 in reply to Davor Pavlovski
    Prodigy 60 points

    Sorry, my bad the actual part number is LM27762 which is dual output (one positive and one negative) with integrated LDO in it. Based on functional block diagram in datasheet it looks like it uses similar block for charge pumping and the output from charge pump is fed to a LDO.

    So coming back to my question is this chip recommended to be used for ADC application for my TI's ADS1294 chip. I'm essentially eliminating TPS60403, TPS73201 and TPS72301 from the my design. 

    Thanks,

  • 0 in reply to Gaurav Bhatia
    TI__Expert 3611 points

    Hi Gaurav,

    Like you described, the LM27762 has a charge pump and then LDOs to regulate the voltage and reduce the voltage ripple.
    Since the LM27762 also has PFM mode (unlike TPS60403 which operates at a fixed frequency), take a look at Figures 1 and 2 from the datasheet to check if that ripple is suitable for your application.

    Regards,
    Davor