SM8580AM

NIPPON PRECISION CIRCUITS—3

PIN DESCRIPTION

Number

Name

I/O

1. Connect a 0.1µF capacitor between VDD and V S S .

1

CE0N

I

Chip enable 0 input with built-in pull-up resistor.

The SM8580AM can be accessed when CE0N is LOW and CE1 is HIGH.

2

FCON

I

FOUT output frequency select control input (when CE1 is HIGH).

32.768kHz fixed frequency output when FCON is LOW .

Output frequency deter mined by bit FD when FCON is HIGH (when FE bit is 1).

Note that a HIGH-level voltage should be applied to FCON to avoid unwanted 32.768kHz output dur ing

backup.

3

FOUT

O

Frequency set register, frequency output (CMOS output)

4

VTEMP

O

Temper ature voltage output (analog output)

5

AIRQN

O

Alarm interrupt output (N-channel open-drain output)

6

TIRQN

O

Timer interrupt output (N-channel open-drain output)

7A 0

I

Address inputs.

Connect to the microcontroller address bus.

The selected register address is input on this bus when accessing the SM8580AM (positive logic).

8A 1

I

9A 2

I

10

A 3

I

1 1

RDN

I

Read strobe input. Data can be read from SM8580AM when RDN is LOW and WRN is HIGH.

An error will occur if both RDN and WRN are simultaneously LOW .

12

V S S

–

Ground

1 3

WRN

I

W r ite strobe input. Data can be written to SM8580AM when RDN is HIGH and WRN is LOW .

An error will occur if both RDN and WRN are simultaneously LOW .

1 4

D 3

I/O

Data bus input/outputs.

Connect to the microcontroller data bus.

1 5

D 2

I/O

1 6

D 1

I/O

1 7

D 0

I/O

1 8

CE1

I

Chip enable 1 input with built-in pull-down resistor.

The SM8580AM can be accessed when CE0N is LOW and CE1 is HIGH.

FOUT is in output mode when CE1 is HIGH, regardless of the state of CE0N. FOUT is high impedance

when CE1 is LOW .

1 9

N C

–

No connection

2 0

N C

–

No connection

2 1

N C

–

No connection

2 2

X T N

O

2 3

X T

I

2 4

V D D

–

Supply