2-201

Preliminary Information

MH88628

20

N1

Network Balance Node 1(Input). 0.1 times the impedance between pins N1 and N2 must

match the device’s input impedance, while 0.1 times the impedance between pins N1 and

AGND is the device’s network balance impedance. This node is active only when NS is at

logic high. This node may be terminated when not used (i.e., NS at logic low).

21

N2

Network Balance Node 2 (Output). See N1 for description.

22

Z900

Line Impedance 900

Ω Node. Connects to Z1 for a line impedance of 900Ω. This node

should be left open circuit when not used.

23

Z1

Line Impedance Node 1 (Input). 0.1 times the times the impedance between pins Z1 and

Z2 is the device’s line impedance. This node must always be connected.

24

Z2

Line Impedance Node 2 (Output). 0.1 times the times the impedance between pins Z1

and Z2 is the device’s line impedance. This node should be left open circuit when not used.

25

TX

Transmit (Output). 4-Wire (AGND) referenced audio output.

26

RX

Receive (Input). 4-Wire (AGND) referenced audio input.

27

GTX0

Transmit Gain Node 0. Connects to GTX1 for 0dB transmit gain.

28

GTX1

Transmit Gain Node 1. A resistor to AGND provides transmit gain adjustment.

29

GRX0

Receive Gain Node 0. Connects to GRX1 for 0dB gain.

30

GRX1

Receive Gain Node 1. A resistor to AGND provides receive gain adjustment.

31

ACRI

AC Ringing Voltage Input. A 1.5Vrms 20Hz signal is applied to this input.

32

Z600

Line Impedance 600

Ω.

This pin should be left open circuit when not used.

33

NS

Network Balance Setting (Input). The logic level at NS selects the network balance

While a logic 1 enables an external balance 0.1 times the impedance between pins N1 and

AGND balanced to 0.1 times the impedance between pins N1 and N2. The impedance

34

SHK

Off-Hook Indication (Output). A logic low output indicates when the subscriber equipment

has gone Off-Hook.

35

UD

Unbalance Detect (Output). A log IC low output indicates when the DC current flow in the

Tip and Ring leads is unbalanced, indicating that the subscriber equipment has grounded

the Ring lead.

36,37,38

IC

Internal Connection. These pins are internally connected and must be left open

39

VEE

Negative Supply Voltage. -5V dc.

40

VDD

Positive Supply Voltage. +5V dc.

Pin Description (Continued)

Pin #

Name

Description