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TPS61085 Voltage Drop on Load

Kshitij Kumar
Prodigy 180 points
Other Parts Discussed in Thread: TPS61085, TPS61087

Hello

I am using TPS61085 for LCD Backlight glowing. I want to generate 12V @ 600mA on output, from 3.8V,3A lithium-ion battery.

I am using the application circuit given in the datasheet of TPS61085, with a 6.8uH inductor.

I am getting perfect 12V in NO LOAD condition, But as soon as i connect to Load the voltage drop happens on output, from 12V it drops to 5.5 Volt.

I have checked datasheet throughly and made my calculations also correctly, still i am unable to avoid voltage drop.

Please Help me in this

Thanks in advance!!

Best Regards,

Kshitij

  • 0
    TI__Guru 65200 points

    Hello Kshitij,

    For a boost converter, the output current is not the same as the switch current. Please check the application note "Basic Calculations of a Boost Converter's Power Stage" SLVA372 for the switch current you have to consider.

    With the above voltages and currents given, the switch current will be higher than 2A. In addition, I expect that the voltage on the LiIon battery will reduce when you apply the load which increases the switch current further.

    I expect that the switch current limit of the part limit the energy transferred from the input to the output and the output voltage drops.

    TPS61087 should have enough switch current limit to drive your load.

    Best regards,
    Brigitte