Hello,
My customer is designing with TPS56921 referring EVM desgin. Let me confirm below design for below usage condition.
Vin: 12V, Vout: 1.0V, Iout: 1A (max), Fsw: 400kHz
1. Can 1.5uH of L1 inductance be used?
2. Can below components for COMP pin with above condition?
My customer had evaluated on EVM, so they referred it. But Webench shows different values.
Best regards,
Katsu
Hi Katsu,
1. The inductor current ripple will be too large with 1.5uH inductance in your usage condition, because the 1A output current is far from the 9A output current in EVM. For the inductance selection, you can refer to the equation (14) in datasheet. From my calculation, minimum inductance value is about 7.6uH in the condition you provided.
2. To analyze the effects of COMP pin components on the loop, the output capacitance are also needed.
Regards,
Andrew
Hi Katsu,
With the components in schematic, the phase margin is about 70.6 degree at 1A output current in Pspice simulation.
The loop is stable with the components for COMP pin.
Regards,
Andrew
