# One Ramp Mode

In One Ramp mode, the TCD counter counts up until it reaches the CMPBCLR value. Then, the TCD cycle is completed, and the counter restarts from 0x000, beginning a new TCD cycle. The TCD cycle period is:

TTCD_cycle=(CMPBCLR+1)fCLK_TCD_CNT
Figure 1. One Ramp Mode
In the figure above, CMPASET < CMPACLR < CMPBSET < CMPBCLR. In One Ramp mode, this is required to avoid overlapping outputs during the on-time. The figure below is an example where CMPBSET < CMPASET < CMPACLR < CMPBCLR, which has overlapping outputs during the on-time.
Figure 2. One Ramp Mode with CMPBSET < CMPASET
A match with CMPBCLR will always result in all outputs being cleared. If any of the other compare values are bigger than CMPBCLR, their associated effect will never occur. If the CMPACLR is smaller than the CMPASET value, the clear value will not have any effect.