TPS53319: load transient response & OVP

Dylan Zheng

Part Number: TPS53319

Hi,

I am confuse about the cross frequency of TPS53319EVM-136. The cross frequency is about 11.63kH when the switching frequency is 500kHz. Why the EVM has so fast response at such low cross frequency? And what determines its bandwidth？

In addition, I pull the FB pin to gnd to test OVP. The Vout is increased, then the circuit latches OFF the high-side MOSFET driver and latches ON the low-side MOSFET driver, the voltage of LL is low and Vout is decreased as shown in picture. However, why the switches work again after that as shown in picture?

over 7 years ago

0 Henry Nguyen over 7 years ago

TI__Intellectual 2460 points

Hello,

Section 8 of TPS53319 datasheet has an introduction of this D-CAP topology. Also, Ti website has many papers which discussed on this topic. Please see example link here (https://training.ti.com/power-tips-dcap-vs-voltage-mode

0 Henry Nguyen over 7 years ago in reply to Henry Nguyen

TI__Intellectual 2460 points

Hello,
TPS53319 monitors the FB voltage for UV and OV functions. When you pulled down FB to ground, the IC could see the UV instead of OV. Please see section 8.3.8 of datasheet for more details.
Can you please re-post the waveform? I could NOT see the waveform.
Kit

0 Dylan Zheng over 7 years ago in reply to Henry Nguyen

TI__Intellectual 1815 points

OK. The waveform as follows. Thanks for your time.

0 Henry Nguyen over 7 years ago in reply to Dylan Zheng

TI__Intellectual 2460 points

Hello,

You need to monitor the FB voltage on the waveform too. The first group of many pulses are due to the FB shorting to ground. The controller generates more pulses since the FB signal lowering than the reference voltage. It is best to look at the FB signal to know which protection feature kick-in first and last.

Kit

Power management

Power management forum

TPS53319: load transient response & OVP