Panasonic MN101C00 - Manual (Page 136)

Chapter 7 AC Zero-Cross Circuit/Noise Filter
122
Overview
7-1 Overview
The P21/SENS pin is the input pin for the AC zero-cross detection circuit.
The AC zero-cross detection circuit outputs a high level when the input is at
an intermediate level, and a low level at all other times.
AC zero-cross
detection circuit
P21 input/IRQ1
to noise filter
(See figure 7-3-1.)
MUX P21/IRQ1/SENS
FLOAT1
0
7
P7RDWN
PARDWN
–
–
–
–
–
P21IM
Figure 7-1-1 P21 Input Circuit Block Diagram