UPD78C14 datasheet(8/52 Pages) NEC

8 / 52 page

µPD78C14(A)

(Continued)

Input/Output

Function

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 1Note, 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)

VAREF

Input

This pin inputs the reference voltage for the A/D converter and controls the

(Reference

operation for the A/D converter.

Voltage)

AVDD

Power supply pin for the A/D converter

(Analog

VDD)

AVSS

Ground pin for the A/D converter

(Analog

VSS)

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.

VDD

Positive power supply pin

VSS

Ground pin

Note

Pull-up with the following external resistor:

4 (k

Ω) ≤ R ≤ 0.4 tCYC (kΩ)tCYC (unit: ns)

Example

4 (k

Ω) ≤ R ≤ 26 (kΩ): tCYC = 66 (ns) at 15 MHz

4 (k

Ω) ≤ R ≤ 33 (kΩ): tCYC = 83 (ns) at 12 MHz

UPD78C14 Datasheet(PDF) 8 Page - NEC

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