
No. 5931-10/14
LC723732/40/48/56/64
Continued from preceding page.
Pin No.
Symbol
I/O
Function
Equivalent circuit
Voltage sense and general-purpose input shared function port
This input circuit is designed with a low input threshold voltage.
When used as a voltage sense input:
This pin is used to test for power failures on the return from backup mode.
Application can test this condition using the internal SNS flip-flop. The SNS flip-flop
can be tested with the TST instruction.
(This usage requires external components (capacitors and resistors). See the
sample application circuit in the user's manual.)
When used as a general-purpose input port:
When used as a general-purpose input port the pin state can be tested with the
TST instruction.
Unlike the other input ports, input to this pin is not disabled in backup mode and after
a power on reset. As a result, through currents must be taken into account when
designing applications that use this pin as a general-purpose input.
88
SNS
I
Power supply monitor (with interrupt function)
This pin is designed with a high input threshold voltage.
This pin is normally connected to the ACC line and used for power off detection.
When a power off state is detected, the HOLDON flag and the hold interrupt request
flag will be set. To enter backup mode, execute a CKSTP instruction when the HOLD
pin is low. Set this pin high to clear backup mode.
87
HOLD
I
System reset pin
When the CPU is operating or in halt mode, the system is reset when this pin is held
low for at least one machine cycle. Execution starts with the PC pointing to location
0. At this time the SNS flip-flop is set. A low level must be applied for at least 50 ms
when power is first applied.
86
RESET
I
General-purpose input and A/D converter input shared function ports
The IOS1 instruction is used to switch between the general-purpose input and the
A/D converter input functions.
When used as a general-purpose input ports:
The general-purpose input port function is set up with the IOS1 instruction. (In bit
units)
When used as A/D converter input pins:
The A/D converter input port function is set up with the IOS1 instruction. (In bit
units)
The pin whose voltage is to be converted is specified with the IOS1 instruction, and
the conversion is started with the UCC instruction.
Note: Since input is disabled for ports specified for the ADI function, executing an
input instruction for such a port will always return a low level.
Input is disabled in backup mode.
These ports are set up as general-purpose input ports after a power on reset.
85
84
83
82
81
80
79
78
PH0/ADI0
PH1/ADI1
PH2/ADI2
PH3/ADI3
PI0/ADI4
PI1/ADI5
PI2/ADI6
PI3/ADI7
I
General-purpose output ports
Since these are open-drain output circuits, external pull-up resistors are required.
The internal transistors are turned off (resulting in a high-level output) in backup
mode and after a power on reset.
76
75
74
73
PJ0
PJ1
PJ2
PJ3
O
General-purpose I/O and external interrupt shared function ports
The input formats are Schmitt inputs.
The external interrupt function is enabled when the external interrupt enable flag is
set.
When used as general-purpose I/O ports:
The mode (input or output) is set in 1-bit units using the IOS1 instruction.
When used as external interrupt pins:
The external interrupt functions are enabled by setting the corresponding external
interrupt enable flag (INT0EN through INT3EN). Here, the pins must be set to input
mode in advance.
Input is disabled and the pins go to the high-impedance state in backup mode.
These ports are set up as general-purpose input ports after a power on reset.
72
71
70
69
PK0/INT0
PK1/INT1
PK2/INT2
PK3/INT3
I/O
Continued on next page.