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TPL5100: Problem with MOS_DRV times

Marcin Mroz
Prodigy 40 points
Part Number: TPL5100
Other Parts Discussed in Thread: TS5A3160, , TPL5110,

Hello,

I have problem with TPL5100. I'm designing device that needs to be powered on with 16 sec. intervals. I used TPL5100 to accomplish that with an analog switch (TS5A3160 to be exact). I drive analog switch from MOS_DRV. No matter if DONE signal is HIGH or LOW measured time of MOS_DRV LOW signal is just 30ms and then it goes HIGH again. In typical application TPL5100 is driving P channel MOSFET. That can't be correct, because device can be turned on just for 30ms. How do I get TPL5100 to work in correct mode -> TPL5100 waits 16sec and turn on analog switch. After DONE signal is there, TPL5100 should switch off MOSFET and connected load. 

Thanks in advance.

  • 0
    TI__Genius 16845 points
    TPL5110 may be a better fit for your application. TPL5110 uses an external resistor to set the time interval.
    For TPL5110, DONE is low at the beginning of the time interval. When a DONE input arrives after 16s, DRV will return high until the time interval expires.

    Kind regards,
    Lane
  • 0 in reply to Lane Boyd
    Prodigy 40 points

    TPL5100 should have same work principle as TPL5110 as suggested in data sheet on first page. TPL5100  as is is completely useless chip. TPL5100 as well as TPL5110 should wait for DONE signal and turn MOS_DRV HIGH as soon as DONE is HIGH. TPL5100 is basically pulsing 30ms HIGH every time interval regardless of DONE signal. 

  • 0 in reply to Marcin Mroz
    TI__Genius 16845 points
    Based on the datasheet description of the operation, the T_mos_drv pulse width is fixed to 31.25ms typ as given in table 6.5.
    Figure 7.3.2.1 confirms this with Figure 6. T_mos_drv can be shorter than 31.25ms if DONE is received within two internal oscillator periods after MOS_DRV goes low (two internal oscillator periods is 31.25ms).

    I ordered a TPL5100EVM to confirm the actual device behavior matches the datsasheet. Still, I think TPL5110 is a better option.

    Kind regards,
    Lane
  • 0 in reply to Lane Boyd
    Prodigy 40 points

    It's correct. Fixed 31.25ms is almost same time as I measured (30 ms) but this IC is useless with fixed time. It basically emulates watchdog function but this IC shouldn't do that. There are IC that do watchdog function in TPL5XXX line. TPL5100 should behave same as a TPL5110 but with 'digitally' controlled time intervals. Something is wrong with that IC.