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TPS55165-Q1: Low power mode

Shinji Tsuji
Genius 14169 points
Part Number: TPS55165-Q1

Hi team,

Could you advise how does the device handle over current or output short circuit condition while in Low Power mode (PS=High) condition?

In the datasheet it seems over current protection function is disabled if PS=High, correct?

I think if over current or output short circuit occur, output under voltage occur which brings the device into normal mode and current limit is enabled.

Is my understanding correct?

Please also advise if there is a maximum current device keeps Low power mode? Or the Low Power mode works independent to the load current?

regards,

  • 0
    TI__Mastermind 34231 points

    Hi Shinji,

    As datasheet describes: 

    When the device operates in low-power mode, both the average current limit and the peak-current limit protection functions are disabled.

    If PS=high, the device works in low-power mode, there is no overcurrent protection. Unexpected behaviors may happen.

    For low power mode, the max output current is 50mA minimum, shown in datasheet EC table. So if customer application Iout<50mA, customer could set the device work in low power mode. The device doesn't transfer to normal pwm mode at high load range when PS=high.

  • 0 in reply to Zack Liu
    TI__Genius 14169 points

    Hi Zack,

    What does happen if the output current increase above 50mA in Low Power mode?

    It seems there is no automatic mode change feature, the device continues to operate in Low Power mode independent to the output load.

    Because the low power mode operation is not design to handle >50mA, the load current need to be managed <50mA in Low power mode.

    Is my understanding correct?

    There is a description as below in the datasheet Figure 15 state diagram.

    Does it mean the PG low (Vout out of regulation) will put the device back to normal mode even if PS=pulled High?

    "The oscillator is turned off in low-power mode. The oscillator is turned back on upon detecting a negative edge on the PS pin, or a negative edge on the PG pin which requires the device to go out of low-power mode and enter normal mode again."

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Mastermind 34231 points

    Hi Shinji,

    We will do some bench test to verify it soon.

  • +1 in reply to Shinji Tsuji
    TI__Mastermind 27910 points

    Hi Shinji,

    As the attached picture shows, if output current increase above 50mA in Low Power Mode, the output voltage decreases. When Vout is less than the PG undervoltage threshold, the PG is low. As datasheet mentioned, "when the PG pin is low, the level of the PS pin is interpreted as low, regardless of the actual level." Then the device enters FPWM and Vout starts to rise. PG is high again and the device enters PFM again.

    It is not recommended that the Iout is above 50mA in low power mode as both the average current limit and the peak-current limit protection functions are disabled.

    /resized-image/__size/3840x2160/__key/communityserver-discussions-components-files/196/5140.12Vin_2D00_5Vout_2C00_-Iout_3D00_250mA.png

  • 0 in reply to Bryce Xun
    TI__Genius 14169 points

    Hi Bryce,

    Thank you for your explanation in detail. 

    regards,