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LM1086-MIL: Schematic review & Output Voltage 1.25 V

CHO SR
Genius 3265 points
Part Number: LM1086-MIL

Hi,

The customer needs 3.3V and 1.25V output voltage of the LM1086-MIL.

And the minimum output voltage of the LM1086-ADJ is indicated as 1.25V.

Is there a problem with using the 1.25V output voltage?

Please review the schematic of the two output voltages.

  • +1
    TI__Expert 3280 points

    Hi Cho,

    For 1.25V output, there are no problems to use it as long as it is operated within the rated current (3A) and headroom.

    I'll get back with you on the schematic review.

    Regards,

    Bobby

  • +1
    TI__Mastermind 42475 points

    Hi Cho,

    To use the 1.25V output option, the ADJ pin needs to be connected to ground. The way the schematic is drawn the device is configured for VOUT (nom) = 1.28V. 

    Are CE1 and CE3 aluminum electrolytic capacitors? I just want to be sure that the ESR requirement will be satisfied. 

    Regards,

    Nick

  • 0 in reply to Nick Butts
    Genius 3265 points

    Hi Nick,

    CE1, CE3 : aluminum electrolytic capacitor

    But it's changed from a new schematic.

    47uF : aluminum electrolytic capacitor

    22uF : MLCC

    Please review the new schematic.

  • +1 in reply to CHO SR
    TI__Mastermind 42475 points

    Hi Cho,

    The MLCC are an issue at the output. The input and output capacitors need a substantial amount of ESR that MLCC do not provide on their own. They can use MLCC on the output if they add a series resistor to artificially provide the ESR, but as it is right now the device will probably be unstable. 

    Other than that the schematics look good. 

    Regards,

    Nick