2-22

MH88422

Preliminary Information

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1VDD

Positive Power Supply Voltage. +5V.

2AGND

Analog Ground. 4-Wire Ground. Normally connected to System Ground.

3LC

Loop Control (Input). A logic low activates internal circuitry which provides a dc

termination across Tip and Ring. Used for seizing the line and dial pulsing.

4RVLC

Ring Voltage and Current Detect (Output). A logic low indicates that loop current is

detected. The loop current can be due to the external monitor phone or the MH88422 in

the off-hook mode. The RVLC output pulses when the external monitor phone is dial

pulsing or when the MH88422 is dial pulsing via the LC input. In addition, when the

MH88422 is on the on-hook mode, a pulsing output indicates ringing voltage across the

Tip and Ring leads. The pulsing output frequency is twice the ringing frequency.

5NC

No Connection should be made to this pin.

6VX

Transmit (Output). 4-Wire ground (AGND) referenced audio output, biased at 2.5V.

Outputs in off-hook mode only.

7VR

Receive (Input). 4-Wire ground (AGND) referenced audio input, biased at 2.5V. LC

must be activated low and loop current must be flowing.

8NC

No Connection should be made to this pin.

9

RING

Ring Lead. Connects to the “Ring” lead of the central office through an optional relay

contact. The central office “Tip” and “Ring” leads may be interchanged.

10

TXIN

Transmit (Input). Connects to the “Ring” lead of the central office through a coupling

capacitor.

11

TF

Tip Feed. Connects to the “Tip” lead of the central office through an internal resistor and

an optional external resistor.

12

NC

No Connection should be made to this pin.

13

RLS

Ring Loop Sense (Input). Sense node for ringing voltage detector and the loop current

detector.

14

TIP

Tip Lead. Connects to the “Tip” lead of the central office through an optional relay

contact. The central office “Tip” and “Ring” leads may be interchanged.

RLS

NC

TF

TXIN

LC

NC

TIP

AGND

RING

RVLC

NC

VX

VR

VDD

1

2

3

4

5

6

78

9

10

11

12

13

14