SNIU028D February 2016 – September 2020 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
Note that Sample Trigger 1 and 2, Blanking A and B, and Phase Trigger are shown at logical locations for this specific mode, but they can be placed anywhere within the period.
Cycle Adjust A can be used to adjust pulse widths on individual phases of a multi-phase system. This can be used if current balancing is necessary, for example. The Adaptive Sample Triggers can be used to sample in the middle of the on-time (Adaptive Sample Trigger B - for an average output during on-time), or at the end of the on-time (Adaptive Sample Trigger A - to minimize phase delay). The Adaptive Sample Register provides an offset from the center or end of the on-time for DPWM signal from the chip. This can compensate for external delays, such as FET and gate driver turn-on times.
The Blanking signals are used to disable the CBC fault signal during noise. Generally the noise is caused by DPWM edges. The Blanking registers hold fixed values, so they are easiest to use with fixed edges, rather than with edges that change dynamically. So in this case, the rising edge of DPWM A and the falling edge of DPWM B are easy to provide blanking for. In this mode, both blanking times act on the falling edge of A, since this is what the Cycle By Cycle logic works on.
Cycle Adjust B has no effect in Normal Mode.
In Normal Mode, the DPWM calculated rising edge of DPWMB must not be permitted to exceed DPWM Event 4. This can be done either with a clamp on the filter output, or by using an appropriate KCOMP value in the filter output multiply operation. If this is not done, the DPWMB on time may overlap the DPWMA on time, causing shoot through