The TPS546E25 device
provides several options for tuning the output voltage feedback and response to transients.
The PMBus command Section 7.67
includes all the GAIN and RAMP settings, a subset of the GAIN and RAMP settings are also
selectable through prinstrapping through Programming MSEL2.
- RAMP: This sets the internal inner-loop
full cycle RAMP amplitude. Smaller ramp settings result in faster response to load
transient events, but also lead to increased off-time jitter. Likewise, large ramp
settings result in reduced frequency jitter, but become slower to respond to an output
voltage deviation. The ramp setting, along with GAIN, inductor and output capacitance
also affects the small-signal bandwidth of the converter. There are two settings
available through Programming MSEL2, and four options through PMBus command COMP.
- GAIN sets the propotional gain from the
sensed output voltage - VOSNS when using the internal feedback divider, or VSEL/FB when
using an external feedback divider. GAIN, along with RAMP, and inductor, sets the
forward transconductance from the sensed output voltage to the Inductor current as the
inverse of Equation 5. There are three settings available through Programming MSEL2 and twelve though PMBus command COMP.
- INT_TIME is the Integration Time
Constant. The Integration Time Constant affects the settling and response time following
an input or output transient. The default is for the INT_TIME is set automatically based
on the switching frequency and can be overridden through the COMP
register.