8
µ
PD78C14(A)
(Continued)
Pin
Input/Output
Function
RD
Output
This is a strobe signal output to read data from external memory. This signal
(Read
becomes high level except during the data read machine cycle for external memory.
Strobe)
This signal becomes output high impedance when the RESET signal is low or in
the hardware STOP mode.
ALE
Output
This is a strobe signal to externally latch the low-order address information
(Address
output to pins PD7-PD0 to access the external memory. This signal becomes
Latch
output high impedance when the RESET signal is low or in the hardware STOP
Enable)
mode.
MODE0
Input/Output
Set the MODE0 pin to 0 (low level) and MODE1 pin to 1 (high level)
Note
.
MODE1
When both pins MODE0 and MODE1 are set to 1
Note
, these pins synchronize to
(Mode)
the ALE and a control signal is output.
NMI
Input
This pin inputs the edge triggering (falling edge) nonmaskable interrupt.
(Non-
Maskable
Interrupt)
INT1
Input
This pin inputs edge triggering (rising edge) maskable interrupt. This pin is also
(Interrupt
shared with zero-cross detection pin for AC input.
Request)
AN7-AN0
Input
These eight pins input analog signals for the A/D converter. Pins AN7-AN4 can
(Analog
be used as edge detection (falling edge) input.
Input)
V
AREF
Input
This pin inputs the reference voltage for the A/D converter and controls the
(Reference
operation for the A/D converter.
Voltage)
AV
DD
Power supply pin for the A/D converter
(Analog
V
DD
)
AV
SS
Ground pin for the A/D converter
(Analog
V
SS
)
X1, X2
These are crystal connecting pins for the system clock oscillation. When a clock
(Crystal)
is externally supplied, input it through pin X1. Input the clock to X1 and its reverse
phase to X2.
RESET
Input
This pin inputs the active-low reset input signal.
(Reset)
STOP
Input
This pin inputs control signal of the hardware STOP mode. When the low level
(Stop)
of this signal is input, the oscillator stops to operate.
V
DD
Positive power supply pin
V
SS
Ground pin
Note
Pull-up with the following external resistor:
4 (k
Ω
)
≤
R
≤
0.4 t
CYC
(k
Ω
)
t
CYC
(unit: ns)
Example
4 (k
Ω
)
≤
R
≤
26 (k
Ω
): t
CYC
= 66 (ns) at 15 MHz
4 (k
Ω
)
≤
R
≤
33 (k
Ω
): t
CYC
= 83 (ns) at 12 MHz
*