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EM78P221/2N
8-Bit Microcontroller with OTP ROM
38 •
Product Specification (V1.0) 10.19.2007
(This specification is subject to change without further notice)
6.7 Comparator
The EM78P221/2N has one comparator comprising of two analog inputs and one
output. The comparator can be utilized to wake up the EM78P221/2N from sleep
mode. The comparator circuit diagram is depicted in the figure below.
Cin
-
-
+
CMP
Cin+
CO
Cin+
Cin
-
Output
10mV
10mV
Fig. 6-10 Comparator Circuit Diagram & Operating Mode
6.7.1 External Reference Signal
The analog signal presented at Cin– compares to the signal at Cin+, and the digital
output (CO) of the comparator is adjusted accordingly by taking the following notes into
considerations:
NOTE
■ The reference signal must be between Vss and Vdd.
■ The reference voltage can be applied to either pin of the comparator.
■ Threshold detector applications may be of the same reference.
■ The comparator can operate from the same or different reference sources.
6.7.2 Comparator Outputs
The compared result is stored in the CMPOUT of Bank 1-RA.
Bits 3 ~ 4 <CMPCOS1, CMPCOS0> of the Bank 1-RA register. See Section 6.2.18,
Bank 1-RA (CMPCON: Comparator Control Register) for Comparator select bits
function description.