ZHCSFD9B July 2016 – October 2018 TPS61230A
PRODUCTION DATA.
The third step is to check the loop stability. The stability evaluation is to look from a steady-state perspective at the following signals:
When the switching waveform shows large duty cycle jitter or the output voltage or inductor current shows oscillations, the regulation loop may be unstable. This is often a result of board layout and/or L-C combination.
The load transient response is another approach to check the loop stability. During the load transient recovery time, VOUT can be monitored for settling time, overshoot or ringing that helps judge the converter’s stability. Without any ringing, the loop has usually more than 45° of phase margin.
As for the heavy load transient applications such as a 2 A load step transient, a feed forward capacitor in parallel with R1 is recommended. The feed forward capacitor increases the loop bandwidth by adding a zero.