2-262

MH88634K

Preliminary Information

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1TIP

Tip Lead. Connects to the “Tip” lead of the central office

2RING

Ring Lead: Connects to the “Ring” lead of the central office

3XLA

Loop Relay Contact A:. Connects to XLB through the Loop relay (K1) contacts when the

relay is activated. This operates the internal active termination circuitry.

4XLD

Loop Relay Contact D: See XLC for description

5XLB

Loop Relay Contact B: See XLA for description

6XLC

Loop Relay Contact C: Connects to XLD through the loop relay (K1) contacts when the

relay is activated. This operates the internal active termination circuitry.

7IC

Internal Connection: This pin is internally connected and must be left open.

8IC

Internal Connection.: This pin is internally connected and must be left open.

9IC

Internal Connection: This pin is internally connected and must be left open.

10

SO

Service Out Detect (Output). A logic low indicates that the central office “Tip” and “Ring”

are out of service.

11

Rx

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

12

VEE

Negative Supply Voltage. -5V

13

Tx

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

14

RV

Ring Voltage Detect (Output). A logic low indicates that ringing voltage is across the Tip

and Ring leads. Note that this output toggles at the ringing cadence and not at the ringing

frequency.

15

FL

Forward Loop Detect (Output). In the on-hook state, a logic low output indicates that

forward loop battery is present. In the off-hook state, a logic low indicates that forward loop

current is present

16

RL

Reverse Loop Detect (Output): In the on-hook state, a logic low output indicates that

reverse loop battery is present. In the off-hook state, a logic low output indicates that reverse

loop current is present. Reverse loop refers to the Tip lead negative respect to the Ring lead.

TIP

RING

XLA

XLB

XLC

IC

IC

IC

SO

Rx

VEE

Tx

RV

FL

RL

VDD

AGND

LRC

VRLY

LRD

XLD

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21