INTERSIL HC1-5504DLC-9

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May 1997
HC-5504DLC
SLIC
Subscriber Line Interface Circuit
Features
Description
• Pin for Pin Replacement for the HC-5504
The Intersil SLIC incorporates many of the BORSHT functions
on a single IC chip. This includes DC battery feed, a ring relay
driver, supervisory and hybrid functions. This device is
designed to maintain transmission performance in the presence of externally induced longitudinal currents. Using the
unique Intersil dielectric isolation process, the SLIC can operate directly with a wide range of station battery voltages.
• Capable of +5V or +12V (VB+) Operation
• Monolithic Integrated Device
• DI High Voltage Process
• Compatible With
Requirements
Worldwide
PBX
Performance
• Internal Ring Relay Driver
The SLIC also provides selective denial of power. If the PBX
system becomes overloaded during an emergency, the SLIC
will provide system protection by denying power to selected
subscriber loops.
• Allows Interfacing With Negative Superimposed Ringing Systems
The Intersil SLIC is ideally suited for the design of new digital
PBX systems by eliminating bulky hybrid transformers.
• Controlled Supply of Battery Feed Current for Short
Loops (41mA)
• Low Power Consumption During Standby
• Switch Hook Ground Key and Ring Trip Detection
Functions
• Selective Denial of Power to Subscriber Loops
Applications
• Solid State Line Interface Circuit for Analog and Digital PBX Systems
• Direct Inward Dial (DID) Trunks
• Voice Messaging PBXs
• Allows Multi-Phone Operation
Ordering Information
PART
NUMBER
TEMPERATURE
RANGE
PACKAGE
HC1-5504DLC-5
0o to +75oC
HC1-5504DLC-9
-40o to +85oC
HC3-5504DLC-5
0o to +75oC
HC3-5504DLC-9
-40o to +85oC
HC4P5504DLC-5
0o to +75oC
HC4P5504DLC-9
-40o to +85oC
28 Lead PLCC
HC9P5504DLC-5
0o to +75oC
24 Lead SOIC
HC9P5504DLC-9
-40o to +85oC
24 Lead SOIC
24 Lead Ceramic DIP
24 Lead Ceramic DIP
24 Lead Plastic DIP
24 Lead Plastic DIP
28 Lead PLCC
Pinouts
TIP
1
24 TX
RING
TIP
N/C
TX
AG
C4
HC-5504DLC (PLCC)
TOP VIEW
RFS
HC-5504DLC (PDIP, CDIP, SOIC)
TOP VIEW
RING
2
23 AG
4
3
2
1
28
27
26
RFS
3
22 C4
VB+ 4
21 RX
VB+
5
25 RX
C3
5
20 +IN
C3
6
24 +IN
DG
6
19 -IN
DG
7
23 -IN
RS
7
18 OUT
N/C
8
22 N/C
RD
8
17 C2
RS
9
21 OUT
TF
9
16 RC
RF 10
15 PD
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2002. All Rights Reserved
8-19
13
14
15
16
17
18
PD
RF
12
GKD
13 SHD
19 RC
11
SHD
BG 12
TF
N/C
14 GKD
BG
11
20 C2
VB-
VB-
RD 10
File Number
2443.3
Specifications HC-5504DLC
Absolute Maximum Ratings (Note 1)
Operating Conditions
Maximum Continuous Supply Voltages
(V B-) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -60 to +0.5 V
(V B+) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5 to +15 V
(V B+ - VB-) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +75V
Relay Drive Voltage (VRD) . . . . . . . . . . . . . . . . . . . . . . .-0.5 to +15V
Junction Temperature Ceramic . . . . . . . . . . . . . . . . . . . . . . +175oC
Junction Temperature Plastic . . . . . . . . . . . . . . . . . . . . . . . . +150oC
Lead Temperature (Soldering 10 Sec.) . . . . . . . . . . . . . . . . +300oC
Operating Temperature Range
HC-5504DLC-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to +75oC
HC-5504DLC-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to +85oC
Storage Temperature Range . . . . . . . . . . . . . . . . . . -65oC to 150oC
Relay Driver Voltage (VRD ) . . . . . . . . . . . . . . . . . . . . . . . +5 to +12V
Positive Supply Voltage (V B+). . . . . . . 4.75 to 5.25 or 10.8 to 13.2V
Negative Supply Voltage (VB-) . . . . . . . . . . . . . . . . . . . . -42 to -58V
High Level Logic Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 2.4V
Low Level Logic Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 0.6V
Loop Resistance (R L) . . . . . . . . . . . . . . . . . . . . . . . . . 200 to 1200Ω
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.
Electrical Specifications
Unless Otherwise Specified, V B- = -48V, VB+ = +12V and +5V, AG = BG = DG = 0V, Typical Parameters
TA = +25oC. Min-Max Parameters are Over Operating Temperature Range.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
On Hook Power Dissipation
ILONG* = 0, VB+ = +12V
-
170
235
mW
Off Hook Power Dissipation
RL = 600Ω, ILONG* = 0, VB+ = +12V
-
425
550
mW
Off Hook IB+
RL = 600Ω, ILONG* = 0, TA = -40oC
-
-
6.0
mA
Off Hook IB+
RL = 600Ω, ILONG* = 0, TA = +25oC
-
-
5.3
mA
Off Hook IB-
RL = 600Ω, ILONG* = 0
-
35
41
mA
Off Hook Loop Current
RL = 1200Ω, ILONG* = 0
-
21
-
mA
Off Hook Loop Current
RL = 1200Ω, VB- = -42V, ILONG* = 0
TA = +25oC
17.5
-
-
mA
Off Hook Loop Current
RL = 200Ω, ILONG* = 0
36
41
48
mA
TIP to Ground
-
14
-
mA
RING to Ground
-
55
-
mA
TIP to RING
-
41
-
mA
TIP and RING to Ground
-
55
-
mA
Fault Currents
Ring Relay Drive VOL
IOL = 62mA
-
0.2
0.5
V
Ring Relay Driver Off Leakage
VRD = +12V, RC = 1 = HIGH, TA = +25oC
-
-
100
µA
Ring Trip Detection Period
RL = 600Ω
-
2
3
Ring
Cycles
-
-
30
mApk
Switch Hook Detection Threshold
SHD = VOL
18
-
-
mA
SHD = VOH
-
-
12
mA
Ground Key Detection Threshold
GKD = VOL
20
-
-
mA
GKD = VOH
-
-
10
mA
Loop Current During Power Denial
RL = 200Ω
-
±2
-
mA
On Hook Ringing Current
Dial Pulse Distortion
0
-
5
ms
(Note 2)
-
110
-
kΩ
Transmit Output Impedance
(Note 2)
-
10
20
Ω
Two Wire Return Loss
(Referenced to 600Ω + 2.16µF), (Note 2)
SRL LO
-
15.5
-
dB
ERL
-
24
-
dB
-
31
-
dB
2 Wire Off Hook
58
65
-
dB
2 Wire On Hook
60
63
-
dB
50
58
-
dB
Receive Input Impedance
SRL HI
Longitudinal Balance
4 Wire Off Hook
1VRMS 200Hz - 3400Hz, (Note 2) IEEE Method
0 C ≤ TA ≤ +75 C
o
o
8-20
Specifications HC-5504DLC
Electrical Specifications
Unless Otherwise Specified, V B- = -48V, VB+ = +12V and +5V, AG = BG = DG = 0V, Typical Parameters
TA = +25oC. Min-Max Parameters are Over Operating Temperature Range. (Continued)
PARAMETER
Low Frequency Longitudinal Balance
Insertion Loss
CONDITIONS
R.E.A. Method, (Note 2), RL = 600Ω
0oC ≤ TA ≤ +75oC
TYP
MAX
UNITS
-
-
23
dBrnC
-
-
-67
dBm0p
-
±0.05
±0.2
dB
-
±0.02
±0.05
dB
-
1
5
dBrnC
-
-89
-85
dBm0p
at 1kHz, 0dBm Input Level, Referenced 600Ω
2 Wire - 4 Wire, 4 Wire - 2 Wire
Frequency Response
200 - 3400Hz Referenced to Absolute Loss at
1kHz and 0dBm Signal Level (Note 2)
Idle Channel Noise
(Note 2)
2 Wire - 4 Wire, 4 Wire - 2 Wire
Absolute Delay
MIN
(Note 2)
-
-
2
ms
Trans Hybrid Loss
2 Wire - 4 Wire, 4 Wire - 2 Wire
Balance Network Set Up for 600Ω Termination at
1kHz
36
40
-
dB
Overload Level
VB+ = +5V
1.5
-
-
Vpeak
VB+ = +12V
1.75
-
-
Vpeak
2 Wire - 4 Wire, 4 Wire - 2 Wire
Level Linearity
2 Wire - 4 Wire, 4 Wire - 2 Wire
Power Supply Rejection Ratio
VB+ to 2 Wire
At 1kHz, (Note 2) Referenced to 0dBm Level
+3 to -40dBm
-
-
±0.05
dB
-40 to -50dBm
-
-
±0.1
dB
-50 to -55dBm
-
-
±0.3
dB
(Note 2)
15
-
-
dB
VB+ to Transmit
15
-
-
dB
VB- to 2 Wire
15
-
-
dB
VB- to Transmit
15
-
-
dB
VB+ to 2 Wire
30 - 60Hz, RL = 600Ω
30
-
-
dB
VB+ to Transmit
30
-
-
dB
VB- to 2 Wire
30
-
-
dB
VB- to Transmit
30
-
-
dB
-
-
±100
µA
Logic Input Current (RS, RC, PD)
200 - 16kHz RL = 600Ω
0V ≤ VIN ≤ + 5V
Logic Inputs
Logic ‘0’ V IL
-
-
0.8
V
Logic ‘1’ V IH
2.0
-
5.5
V
-
0.1
0.5
V
ILOAD 80µA, VB+ = +12V
2.7
5.0
5.5
V
ILOAD 40µA, VB+ = +5V
2.7
-
5.0
V
Logic Outputs
Logic ‘0’ V OL
Logic ‘1’ V OH
ILOAD 800µA, VB+ = +12V, +5V
* ILONG = Longitudinal Current
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.
2. 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 compliance.
8-21
Specifications HC-5504DLC
Uncommitted Op Amp Specifications
MIN
TYP
MAX
UNITS
Input Offset Voltage
PARAMETER
CONDITIONS
-
±5
-
mV
Input Offset Current
-
±10
-
nA
Input Bias Current
-
20
-
nA
Differential Input Resistance
(Note 2)
-
1
-
MΩ
Output Voltage Swing
RL = 10K, VB+ = +12V
-
±5
-
V PEAK
RL = 10K, VB+ = +5V
-
±3
-
V PEAK
Output Resistance
AVCL = 1 (Note 2)
-
10
-
Ω
Small Signal GBW
(Note 2)
-
1
-
MHz
Pin Descriptions
28 PIN
PLCC
24 PIN
DIP/SOIC
SYMBOL
DESCRIPTION
2
1
TIP
An analog input connected to the TIP (more positive) side of the subscriber loop through a 150Ω feed
resistor and a ring relay contact. Functions with the Ring terminal to receive voice signals from the
telephone and for loop monitoring purposes.
3
2
RING
An analog input connected to the RING (more negative) side of the subscriber loop through a 150Ω
feed resistor and a ring relay contact. Functions with the Tip terminal to receive voice signals from the
telephone and for loop monitoring purposes.
4
3
RFS
Senses ring side of loop for ground key and ring trip detection. During ringing, the ring signal is inserted into the line at this node and RF is isolated from RFS via a relay.
5
4
VB +
Positive Voltage Source - Most positive supply. VB+ is typically 12V or 5V.
6
5
C3
Capacitor #3 - An external capacitor to be connected between this terminal and analog ground.
Required for proper operation of the loop current limiting function, and for filtering V B-. Typical value
is 0.3µF, 30V.
7
6
DG
Digital Ground - To be connected to zero potential and serves as a reference for all digital inputs and
outputs on the SLIC microcircuit.
9
7
RS
Ring Synchronization Input - A TTL - compatible clock input. The clock should be arranged such that
a positive pulse transition 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
relay activates and deactivates when the instantaneous ring voltage is near zero. If synchronization
is not required, the pin should be tied to +5V.
10
8
RD
Relay Driver - A low active open collector logic output. When enabled, the external ring relay is
energized.
11
9
TF
Tip Feed - A low impedance analog output connected to the TIP terminal through a 150Ω feed resistor.
Functions with the RF terminal to provide loop current, feed voice signals to the telephone set, and
sink longitudinal current.
12
10
RF
Ring Feed - A low impedance analog output connected to the RING terminal through a 150Ω feed
resistor. Functions with the TF terminal to provide loop current, feed voice signals to the telephone
set, and sink longitudinal current.
13
11
VB -
Negative Voltage Source - Most negative supply. VB- is typically -48V with an operational range of
-42V to -58V. Frequently referred to as “battery”.
14
12
BG
Battery Ground - To be connected to zero potential. All loop current and some quiescent current flows
into this ground terminal.
16
13
SHD
Switch Hook Detection - A low active LS TTL - compatible logic output.
17
14
GKD
Ground Key Detection - A low active LS TTL - compatible logic output. This output is enabled if the
DC current into the ring lead exceeds the DC current out of the tip lead by more than 20mA, and disabled if this current difference is below an internally set threshold.
18
15
PD
Power Denial - A low active TTL - Compatible logic input. When enabled, the switch hook detect
(SHD) and ground key detect (GKD) are not necessarily valid, and the relay driver (RD) output is disabled.
8-22
Specifications HC-5504DLC
Pin Descriptions (Continued)
28 PIN
PLCC
24 PIN
DIP/SOIC
SYMBOL
DESCRIPTION
19
16
RC
Ring Command - A low active TTL - Compatible logic input. When enabled, the relay driver (RD)
output goes low on the next high level of the ring sync (RS) input, as long as the SLIC is not in the
power denial state (PD = 0) or the subscriber is not already off- hook (SHD = 0).
20
17
C2
Capacitor #2 - An external capacitor to be connected between this terminal and digital ground.
Prevents false ground key indications from occurring during ring trip detection. Typical value is
0.15µF, 10V. This capacitor is not used if ground key function is not required and (Pin 17) may be left
open or connected to digital ground.
21
18
OUT
23
19
-IN
The inverting analog input of the spare operational amplifier.
24
20
+IN
The non-inverting analog input of the spare operational amplifier.
25
21
RX
Receive Input, Four Wire Side - 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 300Ω of feed resistance on each side of
the line.
26
22
C4
Capacitor #4 - An external capacitor to be connected between this terminal and analog ground. This
capacitor prevents false ground key indication and false ring trip detection from occurring when
longitudinal currents are induced onto the subscriber loop from near by power lines and other noise
sources. This capacitor is also required for the proper operation of ring trip detection. Typical value is
0.5µF, to 1.0µF, 20V. This capacitor should be nonpolarized.
27
23
AG
Analog Ground - To be connected to zero potential and serves as a reference for the transmit output
(TX) and receive input (RX) terminals.
28
24
TX
Transmit Output, Four Wire Side - A low impedance analog output which represents the differential
voltage across Tip and Ring. Transhybrid balancing must be performed (using the SLIC microcircuit’s
spare op amp) beyond this output to completely implement two to four wire conversion. 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.
NC
No Internal Connection.
1,8,15,22
The analog output of the spare operational amplifier. The output voltage swing is typically ±5V.
NOTE: All grounds (AG, BG, & DG) must be applied before VB+ or VB-. 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.
Functional Diagram
RING SYNC
RING COMMAND
RING
TRIP
RS
RC
RD
RING
CONTROL
SHD SWITCH HOOK
DETECTION
GKD GROUND KEY
LOOP
MONITORING
DETECTION
1/2 RING
RELAY
TIP
TIP
150Ω
DIFF
AMP
+
150Ω
TX
TRANSMIT
OUTPUT
TF
2 WIRE
LOOP
BG
SECONDARY
PROTECTION
BATTERY
FEED
V B-
VB-
OUT
+1
+IN
RF
LOOP
CURRENT
LIMITER
RFS
1/2 RING
RELAY
+
LINE
DRIVERS
RING
VOLTAGE
-IN
150Ω
RING
150Ω
OP
AMP
RING
POWER DENIAL
PD
-1
SLIC MICROCIRCUIT
VB-
8-23
RX
RECEIVE
INPUT
HC-5504DLC
Schematic
SLIC FUNCTIONAL SCHEMATIC
(DIP/SOIC PIN NUMBERS SHOWN)
21
22
11
12
23
6
4
20
19
18
RX
C4
VBAT
BAT
GND
ANA
GND
DIG
GND
VB+
+
-
OUT
VB +
VB+
VB1
VB2
VB3
VB4
VB5
+5V
VOLTAGE & CURRENT
BIAS NETWORK
A-400
TIP FEED
AMP
TF
V
9
IB1 IB2 IB3 IB4 IB5 IB6 IB7 IB8 VBATIB9 IB10 IB11
VB2
-
BAT
RING TRIP DETECTOR
IB4
R12
-
R8
VB+
R9
R22
IB7
IB8
SWITCH HOOK
DETECTOR
IB6
17
VB+
SHD
SH
+
R6
-
13
VB1
IB6
R16
QD27
VBAT/2 REFERENCE
R15
VB2
R14
R
18
RC
THERMAL
LIMITING
LOAD CURRENT
LIMITING I
B2
R21
-
QD28
16
RFC
VB5
+
A-300
RING FEED
AMP
PD
VB5
15
R
19
+
VBAT
C2
STTL
AND LOGIC
INTERFACE
VBAT
VBAT
-
R1
VB+
R2
10
14
+
VB3
A-100
TRANSV’L
I/V AMP
R4
RF
GKD
GND SHORTS
CURRENT
LIMITING
R5
V + VBAT
R23 B
+
2
VB4
+
IB1
R3
RING
VBAT
R20
VBAT
+
R11
VBAT
3
GK
A-200
LONG’L
I/V AMP
QD3 QD36
R10
RING
FEED
SENSE
+5V IB10 VB+
+5V
VB+
R7
TIP
1
VBAT
IB3
R17
+
VB+
A-500
OP AMP
IB5
VBAT
R13
VBAT
VBAT
C3
TX
RS
RD
5
24
7
8
8-24
HC-5504DLC
ontinued)
LOGIC GATE SCHEMATIC
C2
LOGIC BIAS
2
DELAY
4
6
8
7
9
3
5
12
10
13
11
RELAY
DRIVER
14
15
TTL
TO
STTL
TTL
TO
STTL
TTL
TO
STTL
TO
R21
STTL
TO
TTL
C
B
A
STTL
TO
TTL
A
B
RS
RC
PD
C
RD
SHD
GKD
SCHOTTKY LOGIC
High voltage surge conditions are as specified in Table 1.
Die Characteristics
Transistor Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Diode Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Die Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 x 102
Substrate Potential . . . . . . . . . . . . . . . . . . . . . . . Connected
Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bipolar-DI
Thermal Constants (oC/W)
θJA
θJC
Ceramic DIP . . . . . . . . . . . . . . . . . . . .
52
15
Plastic DIP . . . . . . . . . . . . . . . . . . . . . .
52
22
PLCC . . . . . . . . . . . . . . . . . . . . . . . . . .
67
29
SOIC . . . . . . . . . . . . . . . . . . . . . . . . . .
76
24
The SLIC will withstand longitudinal currents up to a maximum or 30mArms, 15mArms per leg, without any performance degradation.
.
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.
8-25
TABLE 1
PARAMETER
Longitudinal
Surge
Metallic Surge
TEST
CONDITION
PERFORMANCE
(MAX)
UNITS
10µs Rise/
±1000 (Plastic)
V PEAK
1000µs/Fall
±500 (Ceramic)
V PEAK
10µs Rise/
±1000 (Plastic)
V PEAK
1000µ Fall
±500 (Ceramic)
V PEAK
T/GND
10µs Rise/
±1000 (Plastic)
V PEAK
R/GND
1000µs Fall
±500 (Ceramic)
V PEAK
50/60Hz Current
T/GND
11 Cycles
700 (Plastic)
V RMS
R/GND
Limited to
10Arms
350 (Ceramic)
V RMS
HC-5504DLC
Applications Diagram
+5V TO
+12V
SYSTEM CONTROLLER
15
RS1 CS1
K1A
TIP
SUBSCRIBER
LOOP
14
7
POWER SWITCH GROUND RING RING
SYNC CMD
DENIAL HOOK
KEY
8
DETECT DETECT
RD
RX
1
TIP
TX
RB2 9
SLIC
+IN
TIP FEED
HC-5504DLC
-IN
OP AMP
VB -
RB1
K1B
OUT
10
RING FEED
3
RS2
CS2
RING
16
K1
1
PRIMARY
PROTECTION
13
RB3
C2
RING FEED SENSE
C3
RB4
2
RING
C4
NEG.
BATT.
BATT.
GND.
DIG.
GND.
ANA.
GND.
VB +
11
12
6
23
4
C9
C8
PTC
BALANCE NETWORK
C5
21
C6
24
20
R1
C7
PCM
SWITCHING
FILTER/ NETWORK
CODEC
ZB
19
R3
R2
18
17
5
22
+
C4 C3 C2
+
VB +
-48V
150V PEAK (MAX)
RING GENERATOR
Z1
-48V
FIGURE 1. TYPICAL LINE CIRCUIT APPLICATION WITH THE MONOLITHIC SLIC
Typical Component Values
C2 = 0.15µF, 10V
C3 = 0.3µF, 30V
C4 = 0.5µF to 1.0µF, 10%, 20V (Should be nonpolarized)
C5 = 0.5µF, 20V
C6 = C7 = 0.5µF (10% Match Required) (Note 2)
C8 = 0.01µF, 100V
C9 = 0.01µF, 20V, ±20%
R1 = R2 = R3 = 100k (0.1% Match Required, 1% absolute
value) ZB = 0 for 600Ω Terminations (Note 2)
RB1 = RB2 = RB 3 = RB4 = 150Ω (0.1% Match Required, 1%
absolute value)
RS1 = RS2 =1kΩ, typically.
CS1 = CS2 = 0.1µF, 200V typically, depending on VRING and
line length.
Z1 = 150V to 200V transient protection.
PTC used as ring generator ballast.
NOTES:
1. Secondary protection diode bridge recommended is a 2A, 200V type.
2. To obtain the specified transhybrid loss it is necessary for the three legs of the balance network, C6-R1 and R2 and C7-ZB-R3, to match
in impedance to within 0.3%. Thus, if C6 and C7 are 1µF each, a 20% match is adequate. It should be noted that the transmit output to
C6 sees a -22V step when the loop is closed. Too large a value for C6 may produce an excessively long transient at the op amp output
to the PCM Filter/CODEC.
A 0.5µF and 100kΩ gives a time constant of 50msec. The uncommitted op amp output is internally clamped to stay within ±5.5V and
also has current limiting protection.
3. All grounds (AG, BG, & DG) must be applied before VB+ or VB-. 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.
4. To prevent saturation of longitudinal amplifier during ringing, the ringer current should be limited to less than 30mA peak.
5. Application shows Ring injected ringing, a Balanced or Tip injected configuration may be used.
6. Pin numbers given for DIP/SOIC package.
Additional information is contained in Application Note 549, “The HC-550X Telephone SLICs’’ By Geoff Phillips
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