Rev.1.0
59
C8051F336/7/8/9
externally driven from –0.25 V to (VDD) + 0.25 V without damage or upset. The complete Comparator elec-
The Comparator response time may be configured in software via the CPT0MD register (see
SFR Defini-tion 11.2). Selecting a longer response time reduces the Comparator supply current.
Figure 11.2. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPT0CN. The
user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and
negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3–0 in the Comparator Control Register CPT0CN
(shown in
SFR Definition 11.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. As shown in
Figure 11.2, settings of 20, 10 or 5 mV of negative hysteresis can be pro-
grammed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is
determined by the setting the CP0HYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Inter-
CP0FIF flag is set to logic 1 upon a Comparator falling-edge occurrence, and the CP0RIF flag is set to
logic 1 upon the Comparator rising-edge occurrence. Once set, these bits remain set until cleared by soft-
ware. The Comparator rising-edge interrupt mask is enabled by setting CP0RIE to a logic 1. The
Comparator0 falling-edge interrupt mask is enabled by setting CP0FIE to a logic 1.
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN-
VIN+
INPUTS
CIRCUIT CONFIGURATION
+
_
CP0+
CP0-
CP0
VIN+
VIN-
OUT
VOH
Positive Hysteresis
Disabled
Maximum
Positive Hysteresis
Negative Hysteresis
Disabled
Maximum
Negative Hysteresis
OUTPUT
VOL