Texas Instruments MSP430x1xx - Manual (Page 289)

Comparator_A in Applications
14-23
Comparator_A
Figure 14–22 shows how to add hysteresis to the comparator to prevent output
oscillation.
Figure 14–22. Use CAOUT at an External Pin to Add Hysteresis to the Reference Level
_
+
0
1
CAF
Set
CAIFG
τ ∼ 2 µ s
0
1
0
1
0
1
0
1
CA0
CA1
0
1
P2CA0
P2CA1
VCAREF
CARSEL
0
1
2
3
3 2 1 0
CAREF
0.5
×
VCC
0.25
×
VCC
V
Signal
Voltage
V
Reference
Voltage
1
0
CAEX
If Feedback is Possible
R1
R2
CAON
VCC 0 V
1 0
CAON
VCC 0 V
1 0
e.g.
Capture
Input of
Timer_A
CAOUT to
External Pin
Adding hysteresis can only be done if CAOUT is available externally. Refer to
the device’s data sheet to determine if CAOUT is available at an external pin.
The hysteresis can be calculated as follows:
V
( hyst)
+" R2
R1 ) R2
V
CC