Other Parts Discussed in Thread: LM61460
Hi all -
I am trying to build a buck regulator circuit that can handle Vin = 6.2V to 28V input and, after tweaking the feedback resistors (with digital pots) and restarting the Vreg*, putting out a regulated voltage in the range of Vout = 3.3V to min(12V, c*Vin), at up to 6A, where c will likely be in the range of 0.8 to 0.9. I am looking at using either the LM61460 or a TPS56637 to accomplish this. Though I'll be changing the feedback resistors (when the voltage regulator is off) with this approach, I'm likely stuck using set values for the passives elsewhere in the circuit (specifically, for the L and C of the low-pass filter on the regulated output).
Thus, my questions: do stability considerations render either the LM61460 or the TPS56637 (or, another chip?) better suited for this challenge? Which corner case should use when selecting the L and C when designing this circuit on WEBENCH?
Thanks for the help,
Tom
*Note: specific care will be taken in the software driving the digital pot in order to cycle the power to the switching regulator offcompletely before adjusting the value of the resistance of the digital pot (leveraging a look-up table, which may be recalibrated on the fly) in order to, whenever the value of the digital pot is changed, both (a) reset the (internal) compensation coefficient of the switching regulator IC, and (b) prevent Over Voltage Protection (OVP) from kicking in and triggering a soft restart of the switching regulator IC.
