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TPS3808G01DBVEVM: Question about UVP Settings for TPS3808G01MDBVTEP

teruhiko ono
Prodigy 20 points
Part Number: TPS3808G01DBVEVM
Other Parts Discussed in Thread: TPS54260, TPS3808

Content:

We are using your microcontroller (TMS5704357BGWTEP), power IC (TPS54260MDGQTEP), and reset IC (TPS3808G01MDBVTEP) in our design.

Based on our configuration, the system conditions are as follows:

When we set the POR and UVP thresholds as shown below, the UVP threshold (1.084V) is triggered after the MCU's minimum operating voltage (1.14V) is already violated in the worst-case scenario for the 1.2V power rail.
The same situation applies to the 3.3V power rail as well.

Is this usage acceptable?
If there is a more appropriate configuration, we would appreciate your advice.

System Conditions:

  • TMS5704357BGWTEP: 1.14V–1.32V, 3.00V–3.60V
  • TPS54260MDGQTEP (1.2V rail): 1.1825V–1.2100V–1.2375V
  • TPS54260MDGQTEP (3.3V rail): 3.2210V–3.3066V–3.3931V
  • TPS3808G01MDBVTEP (1.2V POR release): 1.101V–1.173V
  • TPS3808G01MDBVTEP (1.2V UVP release): 1.084V–1.139V
  • TPS3808G01MDBVTEP (3.3V POR release): 2.991V–3.199V
  • TPS3808G01MDBVTEP (3.3V UVP release): 2.946V–3.106V
  • 0
    TI__Mastermind 19670 points

    Hi Teruhiko, 

    I cannot recommend letting the MCU rail fall below the datasheet minimum. I would recommend adjusting the resistor ladder values for the TPS3808G01MDBVTEP to accommodate the minimum values of the rail.

    Jesse  

  • 0
    Prodigy 20 points

    Hi Jesse,

    Thank you for your feedback.

    I understand your point about not letting the MCU rail fall below the datasheet minimum.

    However, even after adjusting the resistor divider for TPS3808G01MDBVTEP, both POR and UVP thresholds increased together and exceeded the desired range.

    Specifically, POR ended up at 1.169 V–1.246 V, which prevents proper startup.

    Given that the supply voltage cannot be changed (because OVP monitoring is handled by another vendor’s IC), is there any way to configure TPS3808G01MDBVTEP so that:

    - POR and UVP thresholds are above 1.14 V (MCU minimum)

    - and below 1.1825 V (TPS54260 UVLO lower limit)?

    If this is not feasible, could you recommend:

    - A reset IC that allows POR and UVP to be separated, or

    - A TI device that can satisfy OVP, UVP, and POR requirements together?

    Additional notes:

    - TPS3808G01MDBVTEP does not allow hysteresis adjustment.

    - Voltage monitoring on the MCU side is not possible.

    Thank you for your support.

  • 0 in reply to Jesse Villanueva
    Prodigy 20 points

    Hi Jesse,

    Thank you for your response and for sharing the SLVA360 application note.

    I’ve reviewed the document in detail, and while it provides a method to add external hysteresis to the TPS3808, it unfortunately does not help in achieving the specific behavior we need.

    To summarize what we’ve confirmed:

    • The TPS3808G01MDBVTEP has a fixed internal reference and does not allow independent adjustment of POR and UVP thresholds.
    • Adjusting the resistor divider affects both thresholds simultaneously, which causes both POR and UVP to shift together.
    • In our case, this results in a POR threshold that exceeds the MCU’s startup range (1.169 V–1.246 V), which prevents proper boot-up.
    • The SLVA360 method only increases hysteresis (i.e., the gap between rising and falling thresholds), but does not allow us to lower the POR threshold while keeping UVP above the MCU minimum.
    • Our supply voltage is fixed due to OVP monitoring by another vendor’s IC, so we cannot shift the supply level to compensate.

    Given these constraints, it appears that TPS3808G01MDBVTEP cannot meet our requirements.

    Could you please recommend:

    • A reset IC that allows independent configuration of POR and UVP thresholds, or
    • A TI device that integrates OVP, UVP, and POR functionality with configurable thresholds?

    Thanks again for your support.

    Best regards,
    Teruhiko Ono