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TPS7A52: Nominal and effective capacity of input/output capacitor

Ryotaro Fukui
Intellectual 2345 points
Part Number: TPS7A52

Hello team,

I received a inquiry from my customer about the capacitance use for the TPS7A52.

Customers expect to use small capacitors due to PCB space and availability. Is it OK to use the 22uF output capacitor?

It is difficult to determine whether 44uF is a nominal or effective capacity from the description in Datasheet 9.1.1.1.

"The TPS7A52 is designed and characterized for operation with ceramic capacitors of 47 µF or greater (22 µF or greater of capacitance) at the output and 10 µF or greater (5 µF or greater of capacitance) at the input. Use at least a 47-µF capacitor at the input to minimize input impedance."

The intended customer use conditions are as follows:

Cin=10uF, Cout=22uF(1608, 6.3V)

VIN=1.5V(typ) 1.4V(min), Vout=0.8-1.2V Iout=1A

Best Regards,

Ryotaro Fukui

  • 0
    TI__Mastermind 29140 points

    Hi Ryotaro,

    22uF is the absolute minimum capacitance that we recommend for the TPS7A52 to maintain stability.  We typically derate our minimum Cout by 50% to account for voltage bias, tolerance, and environmental conditions which will change the value of Cout and lower it.  That is why you see the recommendation of 47 uF but an absolute minimum of 22 uF.  The customer will need to ensure their output capacitance is 22 uF or larger at all times.

    Thanks,

    - Stephen