MH88435-P

Preliminary Information

2-40

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

1

NB1

Network Balance 1. External passive components must be connected between this pin

and NB2.

2

NB2

Network Balance 2. External passive components must be connected between this pin

and NB1.

3

VR+

Differential Receive (Input). Analog input from modem/fax chip set.

4

VR-

Differential Receive (Input). Analog input from modem/fax chip set.

5VX

Transmit (Output). Ground referenced (AGND) output to modem/fax chip set, biased at

+2.0V.

6LC

Loop Control (Input). A logic 1 applied to this pin activates internal circuitry which

provides a DC termination across Tip and Ring. This pin is also used for dial pulse

application.

7ZA

Line Impedance. Connect impedance matching components from this pin to Ground

(AGND).

8

AGND

Analog Ground. 4-Wire ground. Connect to earth.

Positive Supply Voltage. +5V.

10

VBIAS

Internal Reference Voltage. +2.0V reference voltage. This pin should be decoupled

externally to AGND, typically with a 10

11

LOOP

Loop (Output). The output voltage on this pin is proportional to the line voltage across Tip

- Ring, scaled down by a factor of 50.

12,

14,

17,

20,

23,

26

IC

Internal Connection. No connection should be made to this pin externally.

13

RS

Ringing Sensitivity. Connecting a link or resistor between this pin and LOOP (pin 11) will

vary the ringing detection sensitivity of the module.

15

LCD

Loop Condition Detect (Output). Indicates the status of loop current.

16

RV

Ringing Voltage Detect (Output). The RV output indicates the presence of a ringing

voltage applied across the Tip and Ring leads.

IC

IC

LC

IC

TIP

AGND

RING

RV

ZA

VX

VR-

VCC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

VR+

NB1

NB2

VBIAS

LOOP

IC

RS

IC

VLOOP1

VLOOP2

IC

NP

NP

LCD

SC

SC