TPS54627: overshoot and undershoot problem

Will Wang47

Part Number: TPS54627

Hi team,

I'm testing TPS54627 dynamic response using our EVM, my input voltage is 5V, output is 1.05V, and the parameter on our EVM is not changed. The circuit is just as below.

The load switch between 1A and 5A, the dynamic response just as the waveform show. As you can you, the overshoot is for about 45mV, the undershoot is for about 15mV. And I want to know why overshoot is much more bigger than undershoot. I think there may be some relationship with the D-CAP2 mode.

Any comments are highly appreciated.

Thanks and Best Regards,

Will

over 7 years ago

0 Gavin Wang (Zejing) over 7 years ago

TI__Expert 3480 points

It is mainly related to the internal loop parameter. No because of its control method. You can see : www.ti.com/.../tps563208.pdf .
Page 16 -Figure 30, Figure 31, it is also Dcap2 control. But the overshoot and undershoot is approximately the same.

0 Anthony Lang over 7 years ago

TI__Expert 4875 points

Hi Will,

For DCAP2 deivce, delay will have during load step down since it is constant on time control. For load step down, the device will respond to load transient only after on time ends. On contrary, for load step up, there will be no delay and the device will instantaneously open up HSFET to charge the inductor.

Power management

Power management forum

TPS54627: overshoot and undershoot problem