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LP38853: Vin and Vbias sequencing

Part Number: LP38853

In the datasheet for the LP38853 there appears to be two conflicting statements:

  • Under recommended operating conditions:
    • "Vin cannot exceed either Vbias or 4.5V, whichever is lower"
  • Under section 7.3.2:
    • "There is no requirement for the order that Vin or Vbias are applied or removed."

It’s unclear if you can have Vin ramp before Vbias or not. Point 1 indicates Vin cannot be > Vbias (assuming Vbias < 4.5V), but Point 2 suggestions it doesn't matter the order in which Vin and Vbias are ramped, making Vin > Vbias ok during power on.

If, generally, both statements are true then under what conditions can Vin > Vbias?

  • Hi Chris,

    I believe the condition VIN > VBIAS is fine during startup and that the recommended conditions statement is referring to steady-state operation. 

    I don't think the part will be damaged if VIN goes higher than VBIAS, but my guess is that the biasing will be affected when this condition is met. 

    Regards,

    Nick