Pin Descriptions

PIN NUMBER

NAME

DESCRIPTION

DIP

SO

1

1

VDD

Supply voltage pin to external circuits. Output of 5.0 volt regulator.

2

2

RING

Ring detect output signal to the host microprocessor.

3

3

POSTF

Post loop filter signal used by demodulator.

4

4

LFILTER

Loop filter for PLL.

5

5

LINEAFILTER

Filter input from line “A.”

6

6

VCOSET

Center frequency adjustment pin.

7

7

LINEA

“Tip” input from telephone line.

8

8

LINEB

“Ring” input from telephone line.

9

9

VSS

Ground.

10

11

FILTER2

Active filter pin.

11

12

FILTEROUT

Active filter pin.

12

13

AMPIN

Input from active filter.

13

14

FILTER3

Active filter pin.

14

15

LINEBFILTER

Filter input from line “B.”

15

16

FILTER1

Active filter pin.

16

17

PWR

Logic input signal to switch from low current standby mode.

17

18

FSK/BAT

Multiplexed output signal controlled by PWR pin. In standby mode, this is a

low battery (active low) signal. During FSK demodulation, this is the data line

to the

µP (mark = high).

18

19

VIN

Input power supply pin.

10

20

NC on SOIC

ICS1660

5