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TPS1HB08-Q1: How much VOUT abs max voltage or clamp voltage are?

Part Number: TPS1HB08-Q1

Hi team,

Could you tell me your comment about my understandings and questions? 

  1. Vout positive abs max voltage due to inductive load:
    The Vout positive voltage could be VBB + FET body diode voltage drop. So the Vout abs max is depending on VBB abs max; 36V

  2. Vout negative abs max voltage due to inductive load:
    The Vout negative voltage could be depending on "VDS clamp voltage" @ inductive load turning off.

  3. Or does it have Vout abs max negative voltage or its limitation?

Regards,
Ochi

  • Ochi-san,

    When an inductive load turns off the output will go negative so the absolute maximum (or minimum in this case) should be taken in terms of a negative voltage. 

    The voltage that you see on the output during an inductive turnoff will be the battery (VBB) minus the voltage of the integrated VDS clamp (specified as VDSCLAMP in the datasheet). For the TPS1HB08-Q1 VDSCLAMP is specified from 40V to 46V. This means that for an 18V battery (the abs max nominal voltage of the device) the voltage on the output could be between -28V and -22V. 

    The following application note describes, in detail, all of the transient information for driving inductive loads:

    https://www.ti.com/lit/slvae30

  • Hi Logan, 

    Thank you so much. I understood that VOUT clamps VBB-VCLAMP @ inductive load turning off.

    Regards,
    Ochi