Very precise 54V DC power supply

I need to build a very stable DC power supply with a variable output (51 to 56 VDC) at a very low current output ( 100 mA). But the driff and stability needs to be very less than 5 mV. The circuit will not be operating in very significant temperature changes. Which of the many Linear voltage reference should I be considering for this application?

Regards

Santiago Beron

Parents
  • 0
    •  Analog Employees 
    on Aug 8, 2018 10:34 PM

    Hi Santiago,

    I sent your schematic around to a few people here, and they have some suggestions for you:

    1. The customer has a 1uF tantalum cap at the output of the LT1019. Have they tried adding an external resistor in series with the cap to deliberately increase ESR? Although the cap’s ESR was given by the customer as 10Ohm, that number may not be reliable over all conditions.

     

          The configuration in Fig 1 b,  p8 of the LT1019 datasheet, also shown below, might also be less ringy than relying on cap ESR, if the load current is stable and not very high (which it should be in this case, with the next stage being the 2057HV buffer).

     

     

    1. Has the customer tried separating the amplifier from the reference circuit to see if the ringing can be isolated to one specific part?
    2. Rfb around LTC2057HV is 432k, which is somewhat large, and could cause it to ring with parasitic input capacitance, which might be significant in this case given that they’re using a breadboard. We’d recommend a 10pF across the feedback 432kOhm just in case to quash any potential oscillation.
Reply
  • 0
    •  Analog Employees 
    on Aug 8, 2018 10:34 PM

    Hi Santiago,

    I sent your schematic around to a few people here, and they have some suggestions for you:

    1. The customer has a 1uF tantalum cap at the output of the LT1019. Have they tried adding an external resistor in series with the cap to deliberately increase ESR? Although the cap’s ESR was given by the customer as 10Ohm, that number may not be reliable over all conditions.

     

          The configuration in Fig 1 b,  p8 of the LT1019 datasheet, also shown below, might also be less ringy than relying on cap ESR, if the load current is stable and not very high (which it should be in this case, with the next stage being the 2057HV buffer).

     

     

    1. Has the customer tried separating the amplifier from the reference circuit to see if the ringing can be isolated to one specific part?
    2. Rfb around LTC2057HV is 432k, which is somewhat large, and could cause it to ring with parasitic input capacitance, which might be significant in this case given that they’re using a breadboard. We’d recommend a 10pF across the feedback 432kOhm just in case to quash any potential oscillation.
Children
No Data