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LMR33620AP-Q1: Power-Good Thresholds

Part Number: LMR33620AP-Q1


Hello,

I'd like to ask some questions about LMR33620AP-Q1's power-good thresholds.

  1. The specs of LMR33620AP-Q1's power-good thresholds are referred to the FB voltage. Besides, the reference voltage at the FB pin has variation and its own specs (±1.5%). My question is, does the total error of the power-good threshold in a LMR33620AP-Q1 supply circuit include the FB pin's reference voltage error, too?
    • For example, the specs of the VPG-HIGH-UP alone are 105% (Min) and 110% of the FB voltage, but the specs of the FB pin's reference voltage is 0.985 V (Min) and 1.015 V (Max) (i.e. ±1.5%). Therefore, I guess that the total errors of the VPG-HIGH-UP in a supply circuit result in 103% (= 105% × -1.5%) (Min) and 112% (= 110% × +1.5%) (Max). Is it correct?
  2. Do the power-good upper and lower thresholds have a hysteresis?
  3. Do the power-good thresholds for rising and falling have a relation? I'm wondering if the Min VPG-HIGH-UP of 105% and the Max VPG-HIGH-DN of 108% can occur on the same chip, for example.

Best regards,
Shinichi Yokota

  • Hi,

    My answer is shown below.

    1. For a fixed chip, the FB voltage is equal to the internal Vref voltage, which is a fixed value. The range of Vref refers to the error between different chips. For the same chip, this range will not affect the range of PG.

    2. Yes,  the power-good upper and lower thresholds have a hysteresis. You can refer to the picture below

    3. For the same chip, the difference between VPG-HIGH-UP and  VPG-HIGH-DN is fixed. For example, min VPG-HIGH-UP = 105%, so VPG-HIGH-DN = 105%-2%=103%. 

    Hope this can help you. Thanks.

    Aurora

  • Hi,

    I will close this thread due to no reply for a long time. If you have other questions in the future, you can ask them again in E2E. Thanks.

    Aurora