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TPS65132B start up plateau on negative rail

Frank Du
Prodigy 70 points
Other Parts Discussed in Thread: TPS65132L

ZTE used our TPS65132B on their one type smartphone, they found there is a plateau during negative rail start up, this plateau will last tens of ms to hundreds of ms, they want to know why there is a plateau? They don’t see this plateau if they use our P2P part KTD2151(80MA output capacity). Is there any way to get rid of this plateau.

 

  • 0
    TI__Guru 65170 points

    Hello Frank,

    TPS65132B is set by default to a maximum output current of 40mA. It sounds as if the output current needed by the application at startup is higher than 40mA. The part will then charge the output capacitor of the negative converter to the maximum it is able to with the limit of the 40mA.

    If the customer needs 80mA, he needs to reprogram the part to Tablet mode, see page 23 for the description of register 0x03. Bit 6 needs to be set to 1 to get the current capability of 80mA. By programming the EEPROM this can be set permanently, see register 0xFF for programming the EEPROM.

    Details on the mid current application can be found in the datasheet on pages 35 ff.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Prodigy 70 points
    Hi Brigitte,
    thanks for your suggestion! customer try to program ox03 wiht 43H(bit 6 is 1), but they failed to get 80mA output capacity, is there any program step, whether need program 0xFF, what's the data for 0XFF?

    Frank
  • 0 in reply to Frank Du
    TI__Guru 65170 points

    Hello Frank,

    You need to set bit 6 in register 0x03 to 1, then you need to write 0x80 into register 0xFF to copy the content of the registers to the EEPROM, see the last paragraph on page 20 of the datasheet.

    The IC has registers which you can program on the fly while you are checking the IC out. If all registers are set to the correct value and you are fine with them, you need to copy the registers into the EEPROM because the part will always start with the values coming out of the EEPROM.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Prodigy 70 points

    Hi Brigitte,

    thanks!

    will bit6 of 0X03  be permanently stored once write 0x80 inot 0XFF register? so customer should follow below steps:1. set bit 6 of 0X03 register to 1;  2.write 0x80 into 0xFF register; 3. pull up ENP/N by GPIO to start up; Right?

    whether need write 0x80 into 0xFF register every time when power on or or only one time? is there write cycles limit about NVM write?

  • 0 in reply to Frank Du
    TI__Expert 8010 points
    Hello Frank,

    Yes the steps you are described are right. After step 2 the 0x03 register should be set permanently. This means after step 3 Bit 6 of 0x03 register should be set as 1 (check by reading from EEPROM).
    You do not need to write 0x80 into 0xFF register UNLESS you need to change another or different value that you want to program permanently.

    Best Regards.
    Ilona
  • 0 in reply to Ilona
    TI__Prodigy 70 points
    Hi Brigitte,
    ok, thanks!
    how many times this device permit to write 0x80 into 0XFF register? because usually NVM have times limit.
    I summarized customer how to program our device:
    1. write 0x43 into 0x03 register;(for tablet mode,80mA)
    2. delay?
    3. write 0x80 into 0xFF register;(store NVM)
    4.delay?
    5. pull up ENP/N; (hardware enable)
    6. delay 50ms
    7. change output voltage by programming 0x00 and 0x01 register;

    whether need delay at step2 and step4?

    Frank
  • 0 in reply to Frank Du
    TI__Prodigy 70 points

    Hi Brigitte,
    pls help reply below questions!
    How many times this device permit to write 0x80 into 0XFF register? because usually NVM have times limit.
    I summarized customer how to program our device:
    1. write 0x43 into 0x03 register;(for tablet mode,80mA)
    2. delay?
    3. write 0x80 into 0xFF register;(store NVM)
    4.delay?
    5. pull up ENP/N; (hardware enable)
    6. delay 50ms
    7. change output voltage by programming 0x00 and 0x01 register;
    are above steps ok?
     Whether need delay at step2 and step4?

     

    Frank

  • 0 in reply to Frank Du
    TI__Guru 65170 points

    Hello Frank,

    How many times this device permit to write 0x80 into 0XFF register? because usually NVM have times limit.
    [Brigitte] As far as I know 1000 times.


    I summarized customer how to program our device:

    [Brigitte] The customer needs to enable at least one converter before he can reprogram it. If both converters are disabled, the I2C interface is inactive.

    Please find the procedure
     1. pull up ENP and/or ENN; (hardware enable)
    7. change output voltage by programming 0x00 and 0x01 register
    2. write 0x43 into 0x03 register;(for tablet mode,80mA and both discharge functions enabled)
     3. write 0x80 into 0xFF register;(store NVM) 
    4. delay 50ms

    From now on the device will start up with the voltages programmed in step 1.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Prodigy 70 points
    Hi Brigitte,
    thanks for your reply!
    Is there any way to adjust startup slew rate by register? our competitor part have slower startup rise time(1.6ms vs 0.4ms-TPS65132B) to meet display requirement.


    Frank Du
  • 0 in reply to Frank Du
    TI__Guru 65170 points

    Hello Frank,

    We do not have the possibility to adjust the slew rate on TPS65132B, but TPS65132L has a slower startup. Please refer to the Device Comparison Table on page 4 of the datasheet.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Guru 65170 points

    Hello Frank,

    Did this help?

    Best regards,
    Brigitte