SM8224C

SEIKO NPC CORPORATION —4

PIN DESCRIPTION

Number

Name

I/O

Function

1

AGND

O

2

TIP

I

Tip input. Connected to the telephone line through a protection circuit

3

RING

I

Ring input. Connected to the telephone line through a protection circuit

4

TRQ

O

Input-stage amplifier gain-select output. Used to adjust the gain of the input-stage amplifier.

5

GND

–

Ground. Connected to the system ground potential.

6

OSCIN

I

Crystal oscillator input. The crystal oscillator element is connected between this pin and OSCOUT.

7

OSCOUT

O

Crystal oscillator output. The crystal oscillator element is connected between this pin and OSCIN.

8

MODE

I

When MODE is HIGH, and S1 and S0 are both LOW, the device is in power-down state. See table 2.

9

TEST

–

TEST pin. Set OPEN when normal using.

10

DOUT

O

Data output. Demodulated FSK signal output. HIGH level output when CDET goes HIGH.

11

STR

O

Dual-tone confirmation output. Function is selected by S0 and S1. See table 2.

Dual-tone confirmation: Active-LOW output when dual tone detection signal passes through RC time

constant delay circuit.

12

DTDET

O

Dual-tone detector output. HIGH-level output when dual tone is detected.

13

CR

I/O

Dual tone RC time constant circuit connection. The dual tone detection signal passes through the RC

network to generate the STR signal.

14

CDET

O

FSK signal carrier detector output. LOW-level when active carrier is detected.

15

VDD

–

Supply

16

S1

I

Function select bit 1. Selects the device mode in combination with S0 and MODE. See table 2.

17

S0

I

Function select bit 1. Selects the device mode in combination with S1 and MODE. See table 2.

18

DTQ

O

Dual-tone signal input-stage amplifier output. Used to adjust the gain of the input-stage amplifier.

19

DT2

I

Dual-tone signal input-stage operational amplifier inverting input

20

DT1

I

Dual-tone signal input-stage operational amplifier non-inverting input