HC-5524

EIA/ITU 24V PABX SLIC with 25mA
Loop Feed

The HC-5524 telephone Subscriber Line Interface Circuit
integrates most of the BORSCHT functions on a monolithic
IC. The device is manufactured in a Dielectric Isolation (DI)
process and is designed for use as a 24V interface between
the traditional telephone subscriber pair (Tip and Ring) and
the low voltage filtering and coding/decoding functions of the
line card. Together with a secondary protection diode bridge,
the device will withstand 500V induced surges, in plastic
packages. The SLIC also maintains specified transmission
performance

the

presence

externally

induced

longitudinal currents. The BORSCHT functions that the SLIC
provides are:

· Battery Feed with Subscriber Loop Current Limiting

· Overvoltage Protection

· Ring Relay Driver

· Supervisory Signaling Functions

· Hybrid Functions (with External Op-Amp)

· Test (or Battery Reversal) Relay Driver

In addition, the SLIC provides selective denial of power to
subscriber loops, a programmable subscriber loop current
limit from 20mA to 60mA, a thermal shutdown with an alarm
output and line fault protection. Switch hook detection, ring
trip detection and ground key detection functions are also
incorporated in the SLIC device.

The HC-5524 SLIC is ideally suited for line card designs in
PBX and DLC systems, replacing traditional transformer
solutions.

Features

· DI Monolithic High Voltage Process

· Compatible with Worldwide PBX and DLC Performance

Requirements

· Controlled Supply of Battery Feed Current with

Programmable Current Limit

· Operates with 5V Positive Supply (V

· Internal Ring Relay Driver and a Utility Relay Driver

· High Impedance Mode for Subscriber Loop

· High Temperature Alarm Output

· Low Power Consumption During Standby Functions

· Switch Hook, Ground Key, and Ring Trip Detection

· Selective Power Denial to Subscriber

· Voice Path Active During Power Denial

· On-Chip Op Amp for 2-Wire Impedance Matching

Applications

· Solid State Line Interface Circuit for PBX or Digital Loop

Carrier Systems

· Hotel/Motel Switching Systems

· Direct Inward Dialing (DID) Trunks

· Voice Messaging PBXs

· 2-Wire/4-Wire, 4-Wire/2-Wire Hybrid

· Related Literature

- AN9607, Impedance Matching Design Equations

- AN9628, AC Voltage Gain

- AN9608, Implementing Pulse Metering

- AN549, The HC-5502S/4X Telephone Subscriber Line

Interface Circuits (SLIC)

Ordering Information

PART NUMBER

TEMP.

RANGE (

PACKAGE

PKG.

NO.

HC4P5524-9

-40 to 85

44 Ld PLCC

N44.65

HC9P5524-5

0 to 75

28 Ld SOIC

M28.3

Data Sheet

February 1999

File Number

2798.6

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

http://www.intersil.com or 407-727-9207

Intersil Corporation 1999

Absolute Maximum Ratings

(Note 1)

Thermal Information

Maximum Supply Voltages

+) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 7V

+) - (V

-) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Relay Drive Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 15V

Operating Conditions

Operating Temperature Range

HC-5524-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0

C to T

to 75

HC-5524-9 . . . . . . . . . . . . . . . . . . . . . . . . . . -40

C to T

to 85

Relay Driver Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V to 12V
Positive Power Supply (V

+) . . . . . . . . . . . . . . . . . . . . . . . . 5V

Negative Power Supply (V

-). . . . . . . . . . . . . . . . . . . . -20V to -28V

Thermal Resistance (Typical, Note 2)

(

C/W)

PLCC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maximum Junction Temperature (Plastic Package) . . . . . . . . 150

Maximum Storage Temperature Range . . . . . . -65

C to T

to 150

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300

(PLCC and SOIC - Lead Tips Only)

Die Characteristics

Transistor Count. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Diode Count. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Die Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . .174 mils x 120 mils
Substrate Potential. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connected
Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bipolar-DI

CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

NOTES:

1. Absolute maximum ratings are limiting values, applied individually, beyond which the serviceability of the circuit may be impaired.

Functional operability under any of these conditions is not necessarily implied.

is measured with the component mounted on an evaluation PC board in free air.

Electrical Specifications

Typical Parameters are at T

= 25

C, V

+ = 5V, V

- = -24V, AG = DG = BG = 0V. Min-Max Parameters are

Over Operating Positive and Negative Battery Voltages and Over the Operating Temperature Range. All
Parameters are Specified at 600W 2-Wire Terminating Impedance, Unless Otherwise Specified

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

AC TRANSMISSION PARAMETERS

RX Input Impedance

300Hz to 3.4kHz, (Note 3)

100

TX Output Impedance

4-Wire Input Overload Level

300Hz to 3.4kHz, 600

Reference

+1.0

PEAK

2-Wire Return Loss

Matched for 600

(Note 3)

SRL LO

ERL

SRL HI

2-Wire Longitudinal to Metallic Balance Off Hook

Per ANSI/IEEE STD 455-1976,
300Hz to 3400Hz, (Note 3)

4-Wire Longitudinal Balance Off Hook

Per ANSI/IEEE STD 455-1976,
300Hz to 3400Hz, (Note 3)

Low Frequency Longitudinal Balance

R.E.A. Test Circuit

-80

-67

dBmp

LINE

= 40mA, T

= 25

C (Note 3)

dBrnC

Longitudinal Current Capability

LINE

= 40mA, T

= 25

C (Note 3)

RMS

Insertion Loss

2-Wire/4-Wire

-1.58dBm at 1kHz, Referenced 600

0.05

0.2

4-Wire/2-Wire

0dBm at 1kHz, Referenced 600

0.05

0.2

4-Wire/4-Wire

-1.58dBm at 1kHz, Referenced 600

0.2

Frequency Response

300Hz to 3400Hz, Referenced to Absolute Level at
1kHz, 0dBm Referenced 600

(Note 3)

0.02

0.06

Level Linearity
2-Wire to 4-Wire and 4-Wire to 2-Wire

Referenced to -10dBm, (Note 3)

+3 to -40dBm

0.08

-40 to -50dBm

0.12

-50 to -55dBm

0.3

HC-5524

Absolute Delay

(Note 2)

2-Wire/4-Wire

300Hz to 3400Hz

4-Wire/2-Wire

300Hz to 3400Hz

4-Wire/4-Wire

300Hz to 3400Hz

0.95

1.5

Total Harmonic Distortion
2-Wire/4-Wire, 4-Wire/2-Wire, 4-Wire/4-Wire

Reference Level 0dBm at 600

300Hz to 3400Hz (Note 3)

-50

Idle Channel Noise
2-Wire and 4-Wire

C-Message, (Note 3)

dBrnC

Psophometric

-85

dBmp

3kHz Flat

dBrn

Open Loop Voltage (V

TIP

- V

RING

)

+ = 5V, V

- = -24V

15.8

Power Supply Rejection Ratio

+ to 2-Wire

30Hz to 200Hz, R

= 600

(Note 3)

+ to 4-Wire

- to 2-Wire

- to 4-Wire

+ to 2-Wire

200Hz to 16kHz, R

= 600

+ to 4-Wire

- to 2-Wire

- to 4-Wire

Ring Sync Pulse Width

500

DC PARAMETERS

Loop Current Programming

Limit Range

Accuracy

Loop Current During Power Denial

= 200

Fault Currents

TIP to Ground

RING to Ground

120

TIP and RING to Ground

150

Switch Hook Detection Threshold

Ground Key Detection Threshold

Thermal ALM Output

Safe Operating Die Temperature Exceeded

140

160

Ring Trip Detection Threshold

RING

= 105V

RMS

, f

RING

= 20Hz

Ring Trip Detection Period

100

150

Dial Pulse Distortion

0.1

0.5

Relay Driver Outputs

On Voltage V

(PR) = 60mA, I

(RD) = 30mA

0.2

0.5

Off Leakage Current

= 13.2V

100

TTL/CMOS Logic Inputs (F0, F1, RS, TST, PRI)

Logic `0' V

0.8

Logic `1' V

2.0

5.5

Input Current (F0, F1, RS, TST, PRI)

100

Logic Outputs

Logic `0' V

LOAD

= 800

0.1

0.5

Logic `1' V

LOAD

= 40

2.7

Electrical Specifications

Typical Parameters are at T

= 25

C, V

+ = 5V, V

- = -24V, AG = DG = BG = 0V. Min-Max Parameters are

Over Operating Positive and Negative Battery Voltages and Over the Operating Temperature Range. All
Parameters are Specified at 600W 2-Wire Terminating Impedance, Unless Otherwise Specified (Continued)

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

HC-5524

Power Dissipation On Hook

Relay Drivers Off

+ = 5.25V, V

- = -28V, R

LOOP

+ = 5.25V, V

- = -28V, R

LOOP

-4

+ = 5V, V

- = -24V, R

LOOP

= 600

+ = 5V, V

- = -24V, R

LOOP

= 600

-28

-24

UNCOMMITTED OP AMP PARAMETERS

Input Offset Voltage

Input Offset Current

Differential Input Resistance

(Note 3)

Output Voltage Swing

= 10k

P-P

Small Signal GBW

(Note 3)

MHz

NOTE:

3. These parameters are controlled by design or process parameters and are not directly tested. These parameters are characterized upon initial

design release, upon design changes which would affect these characteristics, and at intervals to assure product quality and specification com-
pliance.

Pin Descriptions

SOIC

PLCC

SYMBOL

DESCRIPTION

(Note 4)

Analog Ground - To be connected to zero potential. Serves as a reference for the transmit output and receive
input terminals.

Positive Voltage Source - Most Positive Supply.

Capacitor #C

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

proper operation of the loop current limiting function.

Function Address #1 - A TTL and CMOS compatible input used with F0 function address line to externally se-
lect logic functions. The three selectable functions are mutually exclusive. See Truth Table on front page. F1
should be toggled high after power is applied.

Function Address #0 - A TTL and CMOS compatible input used with F1 function address line to externally se-
lect logic functions. The three selectable functions are mutually exclusive. See Truth Table on front page.

Ring Synchronization Input - A TTL - compatible clock input. The clock is arranged such that a positive pulse
(50

s - 500

s) occurs on the zero crossing of the ring voltage source, as it appears at the RFS terminal. For

Tip side injected systems, the RS pulse should occur on the negative going zero crossing and for Ring injected
systems, on the positive going zero crossing. This ensures that the ring delay activates and deactivates when
the instantaneous ring voltage is near zero. If synchronization is not required, the pin should be tied to +5V.

SHD

Switch Hook Detection - An active low LS TTL compatible logic output. A line supervisory output.

GKD

Ground Key Detection - An active low LS TTL compatible logic output. A line supervisory output.

TST

A TTL logic input. A low on this pin will set a latch and keep the SLIC in a power down mode until the proper
F1, F0 state is set and will keep ALM low. See Truth Table on front page.

ALM

A LS TTL compatible active low output which responds to the thermal detector circuit when a safe operating
die temperature has been exceeded. When TST is forced low by an external control signal, ALM is latched low
until the proper F1, F0 state and TST input is brought high. The ALM can be tied directly to the TST pin to
power down the part when a thermal fault is detected and then reset with F0, F1. See Truth Table on front page.
It is possible to ignore transient thermal overload conditions in the SLIC by delaying the response to the TST
pin from the ALM. Care must be exercised in attempting this as continued thermal overstress may reduce com-
ponent life.

LIMIT

Loop Current Limit - Voltage on this pin sets the short loop current limiting conditions using a resistive voltage
divider.

OUT1

The analog output of the spare operational amplifier.

-IN1

The inverting analog input of the spare operational amplifier.

Electrical Specifications

Typical Parameters are at T

= 25

C, V

+ = 5V, V

- = -24V, AG = DG = BG = 0V. Min-Max Parameters are

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

HC-5524

TIP

An analog input connected to the TIP (more positive) side of the subscriber loop through a feed resistor and
ring relay contact. Functions with the RING terminal to receive voice signals from the telephone and for loop
monitoring purposes.

RING

An analog input connected to the RING (more negative) side of the subscriber loop through a feed resistor.
Functions with the TIP terminal to receive voice signals from the telephone and for loop monitoring purposes.

RFS

Ring Feed Sense - Senses RING side of the loop for Ground Key Detection. During Ring injected ringing the
ring signal at this node is isolated from RF via the ring relay. For Tip injected ringing, the RF and RFS pins must
be shorted.

Receive Input, 4-Wire Side - A high impedance analog input. AC signals appearing at this input drive the Tip
Feed and Ring Feed amplifiers differentially.

Capacitor #2 - An external capacitor to be connected between this terminal and ground. It prevents false ring
trip detection from occurring when longitudinal currents are induced onto the subscriber loop from power lines
and other noise sources. This capacitor should be nonpolarized.

Transmit Output, 4-Wire Side - A low impedance analog output which represents the differential voltage across
TIP and RING. Transhybrid balancing must be performed beyond this output to completely implement two to
four wire conversion. This output is referenced to analog ground. Since the DC level of this output varies with
loop current, capacitive coupling to the next stage is necessary.

PRI

A TTL compatible input used to control PR. PRI active High = PR active low.

An active low open collector output. Can be used to drive a Polarity Reversal Relay.

(Note 4)

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

Ring Relay Driver - An active low open collector output. Used to drive a relay that switches ringing signals onto
the 2-Wire line.

(Note 5)

Feedback input to the tip feed amplifier; may be used in conjunction with transmit output signal and the spare
op-amp to accommodate 2-Wire line impedance matching. (This is not used in the typical applications circuit).

Tip Feed - A low impedance analog output connected to the TIP terminal through a feed resistor. Functions
with the RF terminal to provide loop current, and to feed voice signals to the telephone set and to sink longitu-
dinal currents. Must be tied to TF

Tie directly to TF

in the PLCC application.

Ring Feed - A low impedance analog output connected to the RING terminal through a feed resistor. Functions
with the TF terminal to provide loop current, feed voice signals to the telephone set, and to sink longitudinal
currents. Tie directly to RF2.

Tie directly to RF

in the PLCC application.

The battery voltage source. The most negative supply.

(Note 4)

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

1, 5, 6, 7,

14, 15,
16, 21,
23, 26,
28, 29,

30, 40

No internal connection.

NOTES:

4. All grounds (AG, BG, and DG) must be applied before V

+ or V

-. 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.

5. Although not used in the typical applications circuit, V

may be used in matching complex 2-Wire impedances.

Pin Descriptions

(Continued)

SOIC

PLCC

SYMBOL

DESCRIPTION

HC-5524

Pinouts

HC-5524 (SOIC)

TOP VIEW

HC-5524 (PLCC)

TOP VIEW

VB+

SHD

GKD

TST

ALM

ILMT

OUT 1

-IN 1

TIP

VFB

VTX

VRX

RFS

RING

VB-

PRI

TRUTH TABLE

Action

Normal Loop Feed

RD Active

Power Down Latch
RESET

Power on RESET

Loop Power
Denial Active

N/C

SHD

ALM

GKD

TST

TF1

TF2

VFB

VTX

N/C

PRI

18 19 20 21 22 23 24 25 26 27 28

ILMT

OUT 1

-IN 1

TIP

RING

RFS

VRX

N/C

VB+

VB-

RF2

RF1

N/C

HC-5524

Functional Diagram

DIP OR SOIC

PLCC

OUT1

R/2

TIP

90k

RING

RFS

4.5k

25k

100k

4.5k

90k

RF1

SHD

FAULT

DET

LIMIT

OP AMP

RTD

GKD

BIAS

NETWORK

IIL LOGIC INTERF

TSD

RFC

PRI

ALM

GKD

SHD

TST

REF

VB/2

-IN1

THERM

LTD

R = 108k

90k

100k

90k

OUT 1

R/2

TIP

90k

RING

RFS

4.5k

25k

100k

4.5k

90k

RF1

SHD

FAULT

DET

LIMIT

OP AMP

RTD

GKD

BIAS

NETWORK

IIL LOGIC INTERF

TSD

RFC

PRI

ALM

GKD

SHD

TST

REF

VB/2

-IN 1

TF1

THERM

LTD

90k

TF2

RF2

90k

100k

NOTES:

6. R = 108k

7. NC = 1, 5, 6, 7, 14, 15, 16, 21,

23, 26, 28, 29, 30, 40.

HC-5524

Logic Diagram

Overvoltage Protection and Longitudinal Current Protection

The SLIC device, in conjunction with an external protection
bridge, will withstand high voltage lightning surges and
power line crosses.

High voltage surge conditions are as specified in Table 1.

The SLIC will withstand longitudinal currents up to a maxi-
mum or 40mA

RMS

, 20mA

RMS

per leg, without any perfor-

mance degradation.

TO BIAS
NETWORK

THERMAL
SHUT DOWN

TEST

THERMAL

SHUTDOWN

LATCH

KEY

INJ

A
B
C

GKD

SHD

ALM

L TO TTL

RELAY

DRIVER

TTL TO I

TABLE 1.

PARAMETER

TEST

CONDITION

PERFORMANCE

(MAX)

UNITS

Longitudinal
Surge

s Rise/

1000 (Plastic)

PEAK

1000

s Fall

Metallic Surge

s Rise/

1000 (Plastic)

PEAK

1000

s Fall

T/GND

s Rise/

1000 (Plastic)

PEAK

R/GND

1000

s Fall

50/60Hz Current

T/GND

11 Cycles

700 (Plastic)

RMS

R/GND

Limited to
10A

RMS

HC-5524

All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.

Intersil semiconductor products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time with-
out notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see web site http://www.intersil.com

Typical Applications

Typical Component Values

= 0.5

F, 20V.

= 1.0

10%, 20V (for other values of C2, refer to

AN9667).

= 0.01

F, 50V

20%.

= 0.01

F, 50V

20%.

= 0.01

F, 50V

20%.

= 0.5

F, 20V.

K(Z

- R

/2) = 50k

, (Z

= 600

, K = Scaling Factor = 100).

, R

; Current Limit Setting Resistors.

> 90k

LIMIT

= (.6) (R

+ R

)/(200 x R

), R

typically 100k

= 20k

, R

= 2(R

), K = Scaling Factor = 100).

= R

= 50

(1% absolute, matching requirements cov-

ered in a Tech Brief).

= R

= 1k

typically.

= C

= 0.1

F, 200V typically, depending on V

Ring

and

line length.

= 150V to 200V transient protector. PTC used as ring

generator ballast.

NOTES:

8. All grounds (AG, BG, and DG) must be applied before V

+ or V

-. 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.

9. Application shows Ring Injected Ringing, Balanced or Tip injected configuration may be used.

10. Secondary protection diode bridge recommended is 3A, 200V type.

11. TF

, TF

and RF

, RF

are on PLCC only and should be connected together as shown.

+ C

LIMIT

-IN1

OUT1

FROM PCM
FILTER/CODER

SYSTEM CONTROLLER

PRI RS

SHD GKD

TEST

ALARM

RING

TIP

PTC

PRIMARY

PROTECTION

150V

PEAK

(MAX)

RING

(NOTE 7)

RFS

RING

(NOTE 7)

TIP

SECONDARY
PROTECTION

TO HYBRID

BALANCE

NETWORK

SLIC

HC-5524

(NOTE 6)

K(Z0 - R /2)

FIGURE 1. TYPICAL LINE CIRCUIT APPLICATION WITH THE MONOLITHIC SLIC

HC-5524

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