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LP5900 Power Supply Recommendations

Den L
Intellectual 990 points
Other Parts Discussed in Thread: LP5900

Hello,

I would like to use LP5900 LDO to decrease voltage from 2.87V to 2.5V. In the datasheet the Drop-Out Voltage is 80mV, so it should work... However in the "Power Supply Recommendations" it says that the Input voltage should be "Vout + 1V" for LDO to work properly... which is not really a LOW drop-out per se....

Therefore, as I understand with 2.87V - 2.5V = 0.37V of drop out voltage the LDO won't work properly, is it so?

Could you recommand an LDO with a 2.5V fixed output voltage and and Low-Drop Out, which would work stable with the transition from 2.87V to 2.5V? 

Kind Regards,

Den

  • 0
    TI__Mastermind 22610 points

    Hello Den,

    The LP5900 "Vin = Vout (NOM) + 1 V', reflects the operating Vin where the Electrical characteristics are ensured (i.e. Electrical Characteristics table).

    Yes, you can operate with 370mV of head-room, the LP5900 will certainly be functional - it will not crash, and your particular application may be OK. But some parametrics will deteriorate as Vin-Vout approaches dropout, especially dynamic conditions like PSRR, line transient, and load transient. 

    If load demands are modest and the input voltage is clean, you should be OK.