HC5503T

FN4506 Rev 2.00

Page 4 of 6

June 2004

Pin Descriptions

24 PIN

SOIC

SYMBOL

DESCRIPTION

1

TIP

An analog input connected to the TIP (more positive) side of the subscriber loop through a 150

 feed resistor. Functions

with the Ring terminal to receive voice signals from the telephone and for loop

monitoring purposes.

2

RING

An analog input connected to the RING (more negative) side of the subscriber loop through a 150

 feed resistor.

Functions with the Tip terminal to receive voice signals from the telephone and for loop monitoring purposes.

3VCC

Positive Voltage Source - Most positive supply. VCC is typically 5V.

4

N/C

No Connect. For proper operation this pin should be left floating.

5C1

Capacitor - An external capacitor to be connected between this terminal and analog ground. Required for proper

operation of the voice band hybrid. Typical value is 0.3

F, 30V.

6

DGND

Digital Ground - To be connected to zero potential and serves as a reference for all digital inputs and outputs on the SLIC

microcircuit.

7

RS

This pin should be tied to 5V.

8

N/C

No Connect. For proper operation this pin should be left floating.

9

TF

Tip Feed - A low impedance analog output connected to the TIP terminal through a 150

 feed resistor. Provides voice

signals to the telephone set and sink longitudinal current.

10

RF

Ring Feed - A low impedance analog output connected to the RING terminal through a 150

 feed resistor. Functions

with the TF terminal to provide loop current, feed voice signals to the telephone set, and sink longitudinal current.

11

VBAT

Negative Voltage Source - Most negative supply. VBAT has an operational range of -24V to -58V.

Frequently referred to as “battery”.

12

BGND

Battery Ground - To be connected to zero potential. All loop current and some quiescent current flows into this ground

terminal.

13

SHD

Switch Hook Detection - A low active LS TTL - compatible logic output. This output is enabled for loop currents exceeding

10mA and disabled for loop currents less than 5mA.

14

N/C

No Connect. For proper operation this pin should be left floating.

15

N/C

No Connect. For proper operation this pin should be left floating.

16

N/C

No Connect. For proper operation this pin should be left floating.

17

N/C

No Connect. For proper operation this pin should be left floating.

18

T1

Used during production testing. For proper operation this pin should be connected to pin T2.

19

T2

Used during production testing. For proper operation this pin should be connected to pin T1.

20

T3

Used during production testing. For proper operation this pin should be connected to Analog Ground pin AGND.

21

RX

Receive Input - A high impedance analog input which is internally biased. Capacitive coupling to this input is required.

AC signals appearing at this input differentially drive the Tip feed and Ring feed terminals, which in turn drive tip and ring

through 300

 of feed resistance on each side of the line.

22

N/C

No Connect. For proper operation this pin should be left floating.

23

AGND

Analog Ground - To be connected to zero potential and serves as a reference for the transmit output (TX) and receive

input (RX) terminals.

24

TX

Transmit Output - A low impedance analog output which represents the differential voltage across Tip and Ring. This

output is unbalanced and referenced to analog ground. Since the DC level of this output varies with loop current,

capacitive coupling to the next stage is essential.

NOTE: All grounds (AGND, BGND, and DGND) must be applied before VCC or VBAT. Failure to do so may result in premature failure of the part. If

a user wishes to run separate grounds off a line card, the AG must be applied first.