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LP3972: LP3970 was obsoleted- looking for alternative

Part Number: LP3972
Other Parts Discussed in Thread: TPS65020, TPS65021, TPS65022

Hello Team,

My customer has using the PXA270 processor with the TI Power Management Unit LP3970. Since the LP3970 was obsoleted- and their stocks of it are running low- they are found no option but to re-design the board to work with the LP3972, which- functionally- is the closest to the LP3970. 

They are aware of the NRND status of the LP3972 but it is still an existing part for running products.

could you please advise if there another alternative from TI which can replace LP3970  or LP3972.

if not, please find a technical question about the LP3972 below:

It is written in Table 3 in the datasheet that the Hardware-Enable signal for BUCK2 in the LP3972 is SYS_EN:

But the Block Diagram of the chip shows something different! –see part of that block diagram:

-As you could see for yourself it looks like there is a small arrow coming from BUCK1 towards BUCK2 and it looks like it continues the PWR_EN signal from BUCK1 downwards into BUCK2! The correct drawing should probably be with a small arrow coming from BUCK3 upwards towards BUCK2, continuing the SYS_EN signal into BUCK2. Am I right? Is there truly a mistake in the block diagram? -I believe that Table 3 is correct, and the block diagram is wrong (or misleading)- could you confirm that?

Thanks in advance 

Regards,

Shai

  • Hi Shai,

    There is not a similar replacement for the LP3970 or LP3972.

    The figure is misleading for default configurations since BUCK2 is primarily controlled by SYS_EN.

    BUCK2 can also be re-assigned to PWR_EN using the Logic Output Enable Register at register address 0x84.

    Best Regards,

    Rick S.

  • Hello Richard,

    Thank you very much, I needed your confirmation.

    But I noticed TPS65020/021/022 are not (yet) marked as NRND. What can you say about using one of them instead of the LP3972? Is the software differs from the LP3970 too large? Would you estimate that this difference is even larger than the difference between LP3970 software and LP3972 software?

    Thanks again,

    Shai

  • Hi Shai,

    If your customer does not need multiple integrated LDOs, the TPS6502x is a good recommendation. It is a widely adopted PMIC that supports the PXA270 and has a driver in the Linux Kernel. I estimate there is less difference between the TPS6502x and LP3970.

    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/regulator/tps65023-regulator.c

    I'm not sure what software resources are available for the LP3972.

    Best Regards,

    Rick S.

  • Thanks, the customer will look at it.

    Best regards,
    Shai
  • Hi Rick,

    the customer would probably use in their system either the LP3972 or the TPS65021/22.
    They easily understood the difference between TPS65020 and TPS65021/22. But couldn't find the difference between the TPS65021 and the TPS65022 in the datasheets.
    Could you detail what is the difference between the TPS65021 and the TPS65022?

    Please note that when searching Google for the TI document about the differences the page couldn't load the document-
    And I got the answer from the TI web site: Sorry! We couldn't find your page.

    the link Differences Between TPS65020/021/022 - Texas Instruments
    www.ti.com/lit/an/slva238/slva238.pdf

    Please advise back, Thanks.

    BR,
    Shai
  • Hi Shai,

    Apparently the only difference between the /21 and /22 is Bit 6 in the CON_CTRL2 register (0x05h). In the TPS65022, this bit can be reset by 4 additional events:

    • DCDC1_EN and DCDC3_EN pulled low,
    • HOT_RESET pulled low,
    • RESPWRON active,
    • VRTC below threshold.

    Both the TPS65021 and TPS652022 will reset Bit 6 after a UVLO event.

    Best Regards,

    Rick S.

  • Rick, Thank you.

    BR
    Shai