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LMZ31520: Impedance between VOUT and GND under Power-Off

Part Number: LMZ31520

Hi Team,

My customer is evaluating LMZ31520 on their board now. They would like to know impedance between VOUT pin and PGND pin of LMZ31520 under Power-Off state and also impedance between SENSE+ pin and AGND pin , for inspection of the LMZ31520 on their board.

 - Impedance between VOUT pin and PGND pin of the LMZ31520 under Power-Off state: ? ohm

 - Impedance between SENSE+ pin and AGND pin of the LMZ31520 under Power-Off state: ? ohm
     *ADJ pin to AGND: external 3.521kohm for Vout=0.85V setting

I look forward to your reply.
Thank you.

Best Regards,

Koshi Ninomiya

  • Ninomiya-san,

    I am working on your request.  I will respond on Monday.

  • Hi Ninomiya-san,

    The impedance between VOUT and PGND will be the same as SENSE+ and AGND. The AGND pin is connected to the PGND pin internally as noted in the pin description.

    The impedance from VOUT to ground will either be set by the resistor divider or any other resistance between VOUT and ground on the board. The internal resistor between VADJ and SENSE+ is 1.43kΩ so the total resistance from VOUT to ground due to the resistor divider is 1.43kΩ + 3.521kΩ = 4.951kΩ. If there more resistance from Vout to ground on the board, the impedance will be less than this.

    Let me know if you have any further questions.

    Anthony