em78p257 ELAN Microelectronics Corp, em78p257 Datasheet - Page 43

• Manufacturer Part Number: em78p257
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

4.8 Comparator
This specification is subject to change without prior notice.
1. External Reference Signal
EM78P257A/B has four comparators, consisting of two analog inputs and one output. The comparators can be
employed to wake up from sleep mode. Fig. 15 and Fig. 16 show the circuit of the comparator.
The analog signal that is presented at Cin- compares to the signal at Cin+, and the digital output (CO) of the
comparator is adjusted accordingly.
• The reference signal must be between Vss and Vdd
C I N 2 +
C I N 3 +
C I N 2 -
C I N 3 -
C O 3
C O 2
Cin+
Cin -
Output
E M 7 8 2 5 7 A
-
+
+
-
Cin -
Cin+
+
-
-
+
25mV
Fig. 16 Comparator Operating Modes
Fig. 15 Comparator Pin Assignments
C O 1
C I N 1 +
C I N 1 -
C I N 4 -
C O 4
C I N 4 +
-
43
+
-
CMP
C I N 3 +
C I N 3 -
C I N 2 +
C I N 2 -
C O 3
C O 2
E M 7 8 2 5 7 B
-
+
+
-
+
-
-
+
CO
C I N 1 -
C I N 4 -
C I N 1 +
C I N 4 +
C O 4
C O 1
EM78P257
07.27.2004 (V1.4)
OTP ROM