XC164-16 Datasheet, PDF (172/417 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller with C166SV2 Core Volume 2 (of 2): Peripheral Units

XC164-16 Derivatives
Peripheral Units (Vol. 2 of 2)
Capture/Compare Unit 6 (CAPCOM6)
18.1.5 Hysteresis-Like Control Mode
The hysteresis-like control mode (MSEL6x = 1001_B) offers the possibility to switch off the
PWM output if the input CCPOSx becomes 0 by resetting 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. The setting of bit CC6xST is only possible while CCPOSx = 1.
CC6POSx
Edge
T12R CDIR
Detect
CM_6x
T12_ZM
T12_SSEP
Set/
Reset
Control
Logic
Bit CC6xST
+ Dead-Time
Generation
MCC6xS/R MSELx2
State
Select
Logic
CC6xO
COUT6xO
MCA05525
Figure 18-21 Hysteresis-Like Control Mode Logic
In this mode, the State Bit CC6xST is reset when pin CC6POSx shows a negative edge.
As long as input CC6POSx is 0, the outputs of the State Bit are in passive state. When
CC6POSx is at high level, the outputs can be in active state and are determined by bit
CC6xST (see Figure 18-10 for the state bit logic and Figure 18-15 for the output paths).
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 (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, which 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 be used for standard PWM with overcurrent protection. As long as there
is no low level signal at pin CC6POSx, the output signals are generated in the normal
manner as described in the previous sections. Only if input CC6POSx shows a low level,
e.g. due to the detection of overcurrent, the outputs are shut off to avoid harmful stress
to the system.
User’s Manual
CAPCOM6_X, V2.0
18-28
V2.1, 2004-03