LT1461CIS8-4#PBF

Hello ADI Team,

We are using LT1461 - 4.096V part and seeing more in Load regulation @ 1mA current. We played with so many input & output Capacitors still seeing issue with Load Reg. @ 1mA

Currently using caps are VIN = 2.2uF tantalum and VOUT = 2.2uF close to VOUT pin and one more 2.2uF with bleeder resistor(Both Vout Caps are Ceramic).

Can you please suggest us which type of capacitors are good to maintain VOUT stable for Load Regulation at 1mA current.

Thanks & Regards,

Ravi Chandra. K

  • 0
    •  Analog Employees 
    on Oct 20, 2020 3:44 AM 1 month ago

    Hi Ravi,

    I would like to understand first how the issue is happening.

    • What is the output of the part at no load(0mA)
    • What is the output of the part at 1mA
    • Is there a reason why use a bleeder resistor? Are you going to turn on/off the part supply?

    But pretty sure the capacitor will not affect the load regulation. 

    Regards,

    Mon

  • Hello Mon,

    Actually we are seeing more variation from VOUT @ 0mA to VOUT @ 1mA. 

    Vout Delta is varying from 30uV to 80uV.

    To calculate PPM/MA using below formula

    Load Reg. @ 1 mA= (Vout Delta/4.096/1mA)

    So, when we measured PPM/MA value it's varying from -8 to 4 PPM. It's going negative to positive direction because of this variation is more. 

    To maintain this value to stable thinking like caps should change. 

    And we given bleeder resistor option for Vout & Vin(2.2uF) bulk cap to discharge.

    Thanks & Regards,

    Ravi. K

  • 0
    •  Analog Employees 
    on Nov 23, 2020 12:27 AM 9 days ago in reply to Ravichandra

    Hi Ravi,

    Considering the delta of 30uV to 80uV, this will lead to 7.32ppm/mA to 19.53ppm/mA, Which is still within the specs.

    You have this wide range of delta Vout by just changing 0mA to 1mA all the time? Or are you measuring from different units? Because normally should not change that much even how many time you test delta change of one unit. 

    How do you test your delta Vout? 

    Load regulation in a sense is: when you increase the current being drawn out of the voltage reference, you also increases voltage drop inside of the part which causes the output to decrease. This also happens when sinking, but in this case you are putting additional current that causes output to increase. 

    Regards,

    Mon