User Manual
526
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Capture/Compare Unit 6 (CCU6)
18.3.3.3 Hysteresis-Like Control Mode
The hysteresis-like control mode (T12MSEL.MSEL6x = 1001
B
) offers the possibility to switch off the PWM output
if the input CCPOSx becomes 0 by clearing the State Bit CC6xST. This can be used as a simple motor control
feature by using a comparator indicating, e.g., overcurrent. While CCPOSx = 0, the PWM outputs of the
corresponding channel are driving their passive levels, because the setting of bit CC6xST is only possible while
CCPOSx = 1.
As long as input CCPOSx is 0, the corresponding State Bit is held 0. When CCPOSx is at high level, the outputs
can be in active state and are determined by bit CC6xST (see
for the output paths). The CCPOSx inputs are evaluated with
f
CC6
.
This mode can be used to introduce a timing-related behavior to a hysteresis controller. A standard hysteresis
controller detects if a value exceeds a limit and switches its output according to the compare result.
Depending on the operating conditions, the switching frequency and the duty cycle are not fixed, but change
permanently.
If (outer) time-related control loops based on a hysteresis controller in an inner loop should be implemented,
the outer loops show a better behavior if they are synchronized to the inner loops. Therefore, the hysteresis-
like mode can be used, that combines timer-related switching with a hysteresis controller behavior. For
example, in this mode, an output can be switched on according to a fixed time base, but it is switched off as
soon as a falling edge is detected at input CCPOSx.
This mode can also be used for standard PWM with overcurrent protection. As long as there is no low level
signal at pin CCPOSx, the output signals are generated in the normal manner as described in the previous
sections. Only if input CCPOSx shows a low level, e.g. due to the detection of overcurrent, the outputs are shut
off to avoid harmful stress to the system.