EM78P257
OTP ROM
4.8 Comparator
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.
C O 2
C O 1
-
-
+
+
C I N 1 +
C I N 1 -
C O 2
C O 1
C I N 2 +
C I N 2 -
-
-
+
+
C I N 2 +
C I N 1 +
C I N 2 -
C I N 1 -
EM78257A
EM78257B
C I N 4 -
-
C I N 3 -
C I N 3 +
C O 3
C I N 4 +
C O 4
C I N 3 -
C I N 4 -
C I N 4 +
C O 4
+
-
+
-
C I N 3 +
C O 3
+
-
+
-
Fig. 15 Comparator Pin Assignments
-
Cin
-
CO
CMP
Cin+
+
Cin-
Cin+
Output
25mV
Fig. 16 Comparator Operating Modes
1. External Reference Signal
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
This specification is subject to change without prior notice.
43
07.27.2004 (V1.4)
ELAN [ ELAN MICROELECTRONICS CORP ]
