M38197 Mitsubishi, M38197 Datasheet - Page 43

• Manufacturer Part Number: M38197
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

ZERO CROSS DETECTION CIRCUIT
The zero cross detection circuit compares the voltage applied to
P4
cross detection circuit input bit (bit 7) of the zero cross detection
control register. It is set to “1” when the input voltage is higher than
V
INT
tection comparator or not to do.
When using 100 V AC as input signal, insert an external circuit be-
tween it and P4
resistors used in the external circuit to a value which satisfies the
absolute maximum rating of port P4
Fig. JE-2 Structure of zero cross detection control register
Fig. JE-3 Block diagram of zero cross detection circuit
SS
5
1
/INT
and to “0” when it is lower than V
/ZCR pin can select to either pass through the zero cross de-
1
/ZCR pin and V
P4
5
/INT
5
/INT
1
1
/ZCR
/ZCR pin. Set the input current limiting
SS
. The result can be read from the zero
Zero cross detection comparator
b7
5
.
SS
. The input signal to P4
“0”
“1”
Zero cross detection
ON/OFF selection bit
Zero cross detection
circuit input bit
b0
Noise filter sampling clock
selection bit
Rising/falling
edge switch
f(X
f(X
CIN
Zero cross detection control register
(ZCRCON : address 0039
Zero cross detection ON/OFF selection bit
Not used (returns “0” when read)
Noise filter sampling clock selection bits (INT
One-sided/both-sided edge detection selection bit
Not used (return “0” when read)
Zero cross detection circuit input bit (read only)
IN
b3 b2
5
0 0 : Not use noise filter
0 1 : f(X
1 0 : f(X
1 1 : f(X
)
)
/
0 : Without passing through zero cross detection comparator
1 : Passing through zero cross detection comparator
0 : One-sided edge detection
1 : Both-sided edge detection
0 : Less than 0 V
1 : 0 V or more
IN
IN
IN
Fig. JE-1 External circuit example for zero cross detection
)/64 or f(X
)/128 or f(X
)/256 or f(X
1/64
When not using
the filter
When using
the filter
Divider
Noise filter
CIN
1/28
CIN
CIN
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
One-sided/both-sided edge
detection selection bit
)/64
1/256
100V AC
16
)/128
)/256
)
MITSUBISHI MICROCOMPUTERS
1
)
R
1
INT
interrupt request
R
2
3819 Group
1
/ZCR
V
P4
V
CC
SS
5
/INT
1
/ZCR
43