DATASHEET

IGNS
D ES
W
E
EN T
OR N
ED F P LA C E M
D
N
RE
MME
ECO MENDED 185
R
Data Sheet
T
5
NO
OM
HC5
RE C
HC55183, HC55184
®
August 10, 2010
Extended Reach Ringing SLIC Family
Features
The RSLIC18™ family of ringing subscriber line interface
circuits (RSLIC) supports analog Plain Old Telephone
Service (POTS) in short and medium loop length, wireless
and wireline applications. Ideally suited for remote
subscriber units, this family of products offers flexibility to
designers with high ringing voltage and low power
consumption system requirements.
• Battery Operation to 75V
The HC55183 and HC55184 family operates up to 75V, and
the HC55185 family operates to 100V, which translates
directly to the amount of ringing voltage supplied to the end
subscriber. With 100V operating voltage, subscriber loop
lengths can be extended up to 500Ω (i.e., 5,000 feet) and
beyond.
• Low External Component Count
Other key features across the product family include: low
power consumption, ringing using sinusoidal or trapezoidal
waveforms, robust auto-detection mechanisms for when
subscribers go on or off hook, and minimal external discrete
application components. Integrated test access features are
also offered on selected products to support loopback
testing as well as line measurement tests.
• Dielectric Isolated (DI) High Voltage Design
There are 2 product offerings in the RSLIC18 family:
HC55183 and HC55184. The architecture for this family is
based on a voltage feed amplifier design using low fixed loop
gains to achieve high analog performance with low
susceptibility to system induced noise.
Block Diagram
POL
CDC
FN4519.8
• Low Standby Power Consumption of 50mW
• Peak Ringing Amplitude 95V, 5 REN
• Sinusoidal or Trapezoidal Ringing Capability
• Integrated CODEC Ringing Interface
• Integrated MTU DC Characteristics
• Pulse Metering and On Hook Transmission
• Tip Open Ground Start Operation
• Thermal Shutdown with Alarm Indicator
• 28 Lead Surface Mount Packaging
• HC55183
- Integrated Battery Switch
- 45dB Longitudinal Balance
• HC55184
- Integrated Battery Switch
- Silent Polarity Reversal
- 45dB Longitudinal Balance
• Pb-Free (RoHS Compliant)
Applications
• Wireless Local Loop (WLL)
• Digital Added Main Line (DAML)/Pairgain
VBL
• Integrated Services Digital Network (ISDN)
VBH
• Small Office Home Office (SOHO) PBX
• Cable/Computer Telephony
ILIM
DC
CONTROL
BATTERY
SWITCH
RINGING
PORT
VRS
Related Literature
• AN9824, Spice Model Tutorial of the RSLIC18 AC Loop
TIP
RING
SW+
SW-
VRX
VTX
-IN
VFB
2-WIRE
PORT
TRANSMIT
SENSING
4-WIRE
PORT
TEST
ACCESS
DETECTOR
LOGIC
CONTROL
LOGIC
RTD RD E0 DET ALM
1
BSEL
F2
F1
F0
SWC
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2003, 2005, 2010. All Rights Reserved
RSLIC18™ is a trademark of Intersil Corporation. All other trademarks mentioned are the property of their respective owners.
HC55183, HC55184
Ordering Information (PLCC Package Only)
HC55183ECMZ (Note)
75V
•
45dB
0 to +70 28 Ld PLCC (Pb-free) N28.45
HC55183ECMZ96 (Note)
75V
•
45dB
0 to +70 28 Ld PLCC (Pb-free) N28.45
HC55184ECMZ (Note)
75V
•
•
45dB
0 to +70 28 Ld PLCC (Pb-free) N28.45
HC55184ECMZR4749
(Note)
75V
•
•
45dB
0 to +70 28 Ld PLCC (Pb-free) N28.45
HC55184ECMZ96R4749
(Note)
75V
•
•
45dB
0 to +70 28 Ld PLCC (Pb-free) N28.45
100V
FULL
TEST
PKG.
DWG. #
85V
PART NUMBER
POL
REV
TEMP.
LOOP
RANGE
BACK
(°C)
ONLY LB = 53dB LB = 58dB
BAT
SW
PACKAGE
NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach
materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb
and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or
exceed the Pb-free requirements of IPC/JEDEC J STD-020.
Device Operating Modes
OPERATING MODE
F2
F1
F0
E0 = 1
E0 = 0
Low Power Standby
0
0
0
SHD
GKD
Forward Active
0
0
1
SHD
GKD
Unused
0
1
0
n/a
n/a
Reverse Active
0
1
1
SHD
GKD
Reverse battery loop feed.
Ringing
1
0
0
RTD
RTD
Balanced ringing mode supporting both
sinusoidal, trapezoidal and ringing
waveforms with DC offset.
Forward Loop Back
1
0
1
SHD
GKD
Internal device test mode.
Tip Open
1
1
0
SHD
GKD
Tip amplifier disabled and ring amplifier
enabled. Intended for PBX type applications.
Power Denial
1
1
1
n/a
n/a
2
DESCRIPTION
HC55183
HC55184
MTU compliant standby mode with active
loop detector.
•
•
Forward battery loop feed.
•
•
This is a reserved internal test mode.
Device shutdown.
•
•
•
•
•
HC55183, HC55184
Pinouts
BGND
TIP
4
3
2
1
ILIM
VBL
28 27 26
RD
VBH
TIP
1
ILIM
BGND
2
RING
VBL
3
RD
VBH
4
RING
HC55184
(28 LD PLCC)
TOP VIEW
HC55183
(28 LD PLCC)
TOP VIEW
28 27 26
5
25 RTD
NC
5
25 RTD
6
24 CDC
NC
6
24 CDC
NC
7
23 VCC
NC
7
23 VCC
F2
8
22 -IN
F2
8
22 -IN
9
21 VFB
F1
9
21 VFB
NC
NC
F1
14 15
16
17
18
12
13
14 15
16
17
18
DET
ALM
AGND
NC
POL
VRS
3
BSEL
13
BSEL
12
VRS
20 VTX
19 VRX
NC
10
11
NC
F0
E0
AGND
20 VTX
19 VRX
ALM
10
11
DET
F0
E0
HC55183, HC55184
Absolute Maximum Ratings TA = 25°C
Thermal Information
Maximum Supply Voltages
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7V
VCC - VBAT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85V
Uncommitted Switch Voltage . . . . . . . . . . . . . . . . . . . . . . . . -110V
Maximum Tip/Ring Negative Voltage Pulse (Note 17) . . . . . . . -115V
Maximum Tip/Ring Positive Voltage Pulse (Note 17). . . . . . . . . . .8V
ESD (Human Body Model). . . . . . . . . . . . . . . . . . . . . . . . . . . . 500V
Thermal Resistance (Typical, Note 1)
θJA (°C/W)
PLCC Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
Maximum Junction Temperature Plastic . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . -65°C to +150°C
Pb-Free Reflow Profilesee link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Die Characteristics
Operating Conditions
Temperature Range
Commercial (C Suffix) . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
Positive Power Supply (VCC). . . . . . . . . . . . . . . . . . . . . . . +5V ±5%
Negative Power Supply (VBH, VBL) . . . . . . . . . . . . . . -24V to -75V
Uncommitted Switch (loop back or relay driver) . . . . . +5V to -100V
Substrate Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VBAT
Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bipolar-DI
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact
product reliability and result in failures not covered by warranty.
NOTE:
1. θJA is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
Unless Otherwise Specified, TA = 0°C to +70°C, VBL = -24V, VBH = -85V or -75V, VCC = +5V,
AGND = BGND = 0V, loop current limit = 25mA. All AC Parameters are specified at 600Ω 2-wire terminating
impedance over the frequency band of 300Hz to 3.4kHz. Protection resistors = 0Ω. These parameters apply
generically to each product offering.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
480
-
-
kΩ
78
80
82
V/V
RINGING PARAMETERS (Note 2)
VRS Input Impedance (Note 3)
VRS to 2-Wire, RLOAD = ∞ (Note 4)
Differential Ringing Gain
4-Wire to 2-Wire Ringing Off Isolation
Active mode, referenced to VRS input.
-
60
-
dB
2-Wire to 4-Wire Transmit Isolation
Ringing mode referenced to the differential ringing
amplitude.
-
60
-
dB
160
-
-
kΩ
AC TRANSMISSION PARAMETERS (Notes 5, 6)
Receive Input Impedance (Note 3)
-
-
1
Ω
4-Wire Port Overload Level
THD = 1%
3.1
3.5
-
VPK
2-Wire Port Overload Level
THD = 1%
3.1
3.5
-
VPK
2-Wire Return Loss
f = 300Hz
-
26
-
dB
f = 1kHz
-
32
-
dB
f = 2.3kHz
-
21
-
dB
f = 3.4kHz
-
17
-
dB
20
-
-
mARMS
Transmit Output Impedance (Note 3)
Longitudinal Current Capability (Per Wire) (Note 3)
Test for False Detect
10
-
-
mARMS
4-Wire to 2-Wire Insertion Loss
Test for False Detect, Low Power Standby
-0.20
0.0
+0.30
dB
2-Wire to 4-Wire Insertion Loss
-6.22
-6.02
-5.82
dB
-6.32
-6.02
-5.82
dB
-
16
19
dBrnC
4-Wire to 4-Wire Insertion Loss
Idle Channel Noise 2-Wire
C-Message
Psophometric
-
-73.5
-71
dBmp
Idle Channel Noise 4-Wire
C-Message
-
10
13
dBrnC
Psophometric
-
-79.5
-77
dBmp
4
HC55183, HC55184
Electrical Specifications
Unless Otherwise Specified, TA = 0°C to +70°C, VBL = -24V, VBH = -85V or -75V, VCC = +5V,
AGND = BGND = 0V, loop current limit = 25mA. All AC Parameters are specified at 600Ω 2-wire terminating
impedance over the frequency band of 300Hz to 3.4kHz. Protection resistors = 0Ω. These parameters apply
generically to each product offering. (Continued)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
DC PARAMETERS (Note 6)
Loop Current Limit Programming Range (Note 5)
Max Low Battery = -52V
15
-
45
mA
Loop Current During Low Power Standby
Forward polarity only.
18
-
26
mA
LOOP DETECTORS AND SUPERVISORY FUNCTIONS
Switch Hook Programming Range
Switch Hook Programming Accuracy
Assumes 1% external programming resistor
Dial Pulse Distortion
Ring Trip Comparator Threshold
5
-
15
mA
-
±2
± 10
%
-
1.0
-
%
2.4
2.7
3.0
V
Ring Trip Programming Current Accuracy
-
-
± 10
%
Ground Key Threshold
-
12
-
mA
-
175
-
°C
Thermal Alarm Output
IC junction temperature
LOGIC INPUTS (F0, F1, F2, E0, SWC, BSEL)
Input Low Voltage
-
-
0.8
V
Input High Voltage
2.0
-
-
V
Input Low Current
VIL = 0.4V
-20
-
-
μA
Input High Current
VIH = 2.4V
-
-
5
μA
Output Low Voltage
IOL = 5mA
-
-
0.4
V
Output High Voltage
IOH = 100μA
2.4
-
-
V
LOGIC OUTPUTS (DET, ALM)
POWER SUPPLY REJECTION RATIO
VCC to 2-Wire
VCC to 4-Wire
f = 300Hz
-
40
-
dB
f = 1kHz
-
35
-
dB
f = 3.4kHz
-
28
-
dB
f = 300Hz
-
45
-
dB
f = 1kHz
-
43
-
dB
f = 3.4kHz
-
33
-
dB
VBL to 2-Wire
300Hz ≤ f ≤ 3.4kHz
-
30
-
dB
VBL to 4-Wire
300Hz ≤ f ≤ 3.4kHz
-
35
-
dB
VBH to 2-Wire
300Hz ≤ f ≤ 3.4kHz
-
33
-
dB
VBH to 4-Wire
300Hz ≤ f ≤ 1kHz
-
40
-
dB
1kHz < f ≤ 3.4kHz
-
45
-
dB
NOTES:
2. These parameters are specified at high battery operation. BSEL = 1.
3. These parameters are controlled via design or process parameters and are not directly tested. These parameters are characterized upon initial
design release and upon design changes which would affect these characteristics.
4. Differential Ringing Gain is measured with VRS = 0.663 VRMS for -85V devices and VRS = 0.575 VRMS for -75V devices.
5. These parameters are specified at low battery operation.The external supply is set to BSEL = 0.
6. Forward Active and Reverse Active performance is guaranteed for the HC55184 device only. The HC55183 is specified for Forward Active
operation only.
5
HC55183, HC55184
Electrical Specifications
Unless Otherwise Specified, TA = 0°C to 70°C , VBL = -24V, VCC = +5V, AGND = BGND = 0V, loop current
limit = 25mA. All AC Parameters are specified at 600Ω 2-wire terminating impedance over the frequency band
of 300Hz to 3.4kHz. Protection resistors = 0Ω.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
70
-
-
VPEAK
-
-
-
VPEAK
70
-
-
VPEAK
(Note 8)
-
-
-
VPEAK
VBH = -75V, RL = ∞
-
-
±3
V
(Note 8)
-
-
-
V
VBH = -75V, RL = ∞
-
-
±3
V
(Note 8)
-
-
-
V
Grade E
45
53
-
dB
(Note 10)
-
-
-
dB
Grade E
-
58
-
dB
(Note 10)
-
-
-
dB
+3 to -40dBm, 1kHz
-
±0.025
-
dB
-40 to -50dBm, 1kHz
-
±0.050
-
dB
-50 to -55dBm, 1kHz
-
±0.100
-
dB
Loop Current Accuracy (Notes 5, 6)
IL = 25mA
-
-
± 10
%
Open Circuit Voltage (|Tip - Ring|, Note 6)
VBL = -16V
-
7.5
-
V
VBL = -24V
14
15.5
17
V
VBH = -60V, BSEL = 1
43
50
-
V
VBH = -48V
43
-
47
V
VBH = -60V, BSEL = 1
43
49
-
V
VRG in LPS and FA
VTG in RA
VBH = -60V, BSEL = 1
-
-53
-56
V
-
-
-
-
-
-
RINGING PARAMETERS (Note 2)
Ringing Voltage Open Circuit (Note 7)
THD ≤ 0.5%
VBH = -75V
(Note 8)
Ringing Voltage Load = 1.3K (Notes 7, 9)
Tip Centering Voltage
Ring Centering Voltage
THD ≤ 3.0%
VBH = -75V
AC TRANSMISSION PARAMETERS (Notes 5, 6)
2-Wire Longitudinal Balance (Notes 11, 12)
4-Wire Longitudinal Balance
2-Wire to 4-Wire Level Linearity
4-Wire to 2-Wire Level Linearity
Referenced to -10dBm
DC PARAMETERS
Low Power Standby Open Circuit Voltage (Tip - Ring, Note 2)
Absolute Open Circuit Voltage (Note 6)
TEST ACCESS FUNCTIONS
Switch On Voltage
(Note 13)
-
-
-
V
Loopback Max Battery
(Note 14)
-
-
52
V
SUPPLY CURRENTS (Supply currents not listed are considered negligible and do not contribute significantly to total power dissipation. All
measurements made under open circuit load conditions.)
Low Power Standby (Note 2)
Forward or Reverse (Note 5)
6
ICC
-
3.7
6.0
mA
IBH, VBH = -75V
-
0.375
-
mA
ICC
2.0
4.0
6.0
mA
IBL
-
1.0
2.5
mA
HC55183, HC55184
Electrical Specifications
Unless Otherwise Specified, TA = 0°C to 70°C , VBL = -24V, VCC = +5V, AGND = BGND = 0V, loop current
limit = 25mA. All AC Parameters are specified at 600Ω 2-wire terminating impedance over the frequency band
of 300Hz to 3.4kHz. Protection resistors = 0Ω. (Continued)
PARAMETER
MIN
TYP
MAX
UNITS
ICC
2.0
5.5
8.0
mA
IBL
-
1.3
2.5
mA
IBH, VBH = -75V
-
1.4
3.0
mA
ICC
-
8.5
-
mA
IBL
-
0.4
2.0
mA
IBH, VBH = -75V
-
1.3
2.5
mA
(Note 14)
-
-
-
mA
-
-
-
mA
-
-
-
mA
-
-
-
mA
ICC
-
3.0
6.0
mA
IBL
-
0.2
0.5
mA
Forward or Reverse (Note 5, 6)
VBL = -24V
-
44
60
mW
Low Power Standby (Note 2)
VBH = -75V
-
46
70
mW
(Note 8)
-
-
-
mW
VBH = -75V
-
170
275
mW
(Note 8)
-
-
-
mW
VBL = -24V
-
280
310
mW
Forward (Note 2)
Ringing (Note 2)
Forward Loopback (Note 5)
Tip Open (Note 5)
TEST CONDITIONS
(Note 15)
Power Denial (Note 5)
ON HOOK POWER DISSIPATION (Note 16)
Ringing (Note 2)
OFF HOOK POWER DISSIPATION (Notes 5, 16)
Forward or Reverse
NOTES:
7. Ringing Voltage is measured with VRS = 0.707 VRMS for -85V devices and VRS = 0.619 VRMS for -75V devices. All measurements are at
T = +25°C.
8. The HC55183 and HC55184 devices are specified with a single high battery voltage grade.
9. The device represents a low output impedance during ringing. Therefore the voltage across the ringing load is determined by the voltage divider
formed by the protection resistance, loop resistance and ringing load impedance.
10. The HC55183 and HC55184 are specified with a single longitudinal balance grade.
11. Longitudinal Balance is tested per IEEE455-1985, with 368Ω per Tip and Ring Terminal.
12. These parameters are tested 100% at room temperature. These parameters are guaranteed not tested across temperature via statistical
characterization.
13. The HC55183 and HC55184 do not support uncommitted switch operation.
14. The HC55183 and HC55184 do not support the Forward Loopback operating mode.
15. The HC55183 and HC55184 do not support the Tip Open operating mode.
16. The power dissipation numbers are actual device measurements and will be less than worse case calculations based on data sheet supply
current limits.
17. Characterized with 2 x 10μs, and 10 x 1000μs first level lightning surge waveforms (GR-1089-CORE).
7
HC55183, HC55184
Design Equations
4-WIRE TO 2-WIRE GAIN
Loop Supervision Thresholds
The 4-wire to 2-wire gain is defined as the receive gain. It is
a function of the terminating impedance, synthesized
impedance and protection resistors. Equation 6 calculates
the receive gain, G42.
SWITCH HOOK DETECT
The switch hook detect threshold is set by a single external
resistor, RSH . Equation 1 is used to calculate the value of RSH.
(EQ. 1)
R SH = 600 ⁄ I SH
ZL
⎛
⎞
G 42 = – 2 ⎜ ------------------------------------------⎟
Z
+
2R
⎝ O
P + Z L⎠
(EQ. 6)
The term ISH is the desired DC loop current threshold. The
loop current threshold programming range is from 5mA to
15mA.
When the device source impedance and protection resistors
equals the terminating impedance, the receive gain equals
unity.
GROUND KEY DETECT
2-WIRE TO 4-WIRE GAIN
The ground key detector senses a DC current imbalance
between the Tip and Ring terminals when the ring terminal is
connected to ground. The ground key detect threshold is not
externally programmable and is internally fixed to 12mA
regardless of the switch hook threshold.
The 2-wire to 4-wire gain (G24) is the gain from tip and ring to
the VTX output. The transmit gain is calculated in Equation 7.
RING TRIP DETECT
When the protection resistors are set to zero, the transmit
gain is -6dB.
The ring trip detect threshold is set by a single external
resistor, RRT. IRT should be set between the peak ringing
current and the peak off hook current while still ringing.
(EQ. 2)
R RT = 1800 ⁄ I RT
The capacitor CRT, in parallel with RRT, will set the ring trip
response time.
Loop Current Limit
The loop current limit of the device is programmed by the
external resistor RIL. The value of RIL can be calculated
using Equation 3.
1760
R IL = ------------I LIM
(EQ. 3)
ZO
⎛
⎞
G 24 = – ⎜ ------------------------------------------⎟
⎝ Z O + 2R P + Z L⎠
TRANSHYBRID GAIN
The transhybrid gain is defined as the 4-wire to 4-wire gain
(G44).
ZO
⎛
⎞
G 44 = – ⎜ ---------------------------------------⎟
Z
+
2R
+
Z
⎝ O
P
L⎠
COMPLEX IMPEDANCE SYNTHESIS
Substituting the impedance programming resistor, RS, with a
complex programming network provides complex
impedance synthesis.
2-WIRE
NETWORK
C2
Impedance Matching
RESISTIVE IMPEDANCE SYNTHESIS
The source impedance of the device, ZO , can be calculated
in Equation 4.
(EQ. 4)
R S = 400 ( Z O )
The required impedance is defined by the terminating
impedance and protection resistors as shown in Equation 5.
(EQ. 5)
Z O = Z L – 2R P
8
(EQ. 8)
When the protection resistors are set to zero, the transhybrid
gain is -6dB.
The term ILIM is the desired loop current limit. The loop
current limit programming range is from 15mA to 45mA.
The impedance of the device is programmed with the
external component RS . RS is the gain setting resistor for
the feedback amplifier that provides impedance matching. If
complex impedance matching is required, then a complex
network can be substituted for RS .
(EQ. 7)
R1
PROGRAMMING
NETWORK
CP
RS
R2
RP
FIGURE 1. COMPLEX PROGRAMMING NETWORK
The reference designators in the programming network
match the evaluation board. The component RS has a
different design equation than the RS used for resistive
impedance synthesis. The design equations for each
component are provided in the following.
R S = 400 × ( R 1 – 2 ( R P ) )
(EQ. 9)
R P = 400 × R 2
(EQ. 10)
C P = C 2 ⁄ 400
(EQ. 11)
HC55183, HC55184
Low Power Standby
Overview
The low power standby mode (LPS, 000) should be used
during idle line conditions. The device is designed to operate
from the high battery during this mode. Most of the internal
circuitry is powered down, resulting in low power dissipation.
If the 2-wire (tip/ring) DC voltage requirements are not
critical during idle line conditions, the device may be
operated from the low battery. Operation from the low
battery will decrease the standby power dissipation.
TABLE 1. DEVICE INTERFACES DURING LPS
INTERFACE
ON
OFF
NOTES
Receive
x
Ringing
x
AC transmission, impedance
matching and ringing are
disabled during this mode.
Transmit
x
2-Wire
x
Amplifiers disabled.
Loop Detect
x
Switch hook or ground key.
2-Wire Interface
During LPS, the 2-wire interface is maintained with internal
switches and voltage references. The Tip and Ring
amplifiers are turned off to conserve power. The device will
provide MTU compliance, loop current and loop supervision.
Figure 2 represents the internal circuitry providing the 2-wire
interface during low power standby.
GND
voltage exceeds the MTU reference of -49V (typically), the
Ring terminal will be clamped by the internal reference. The
same Ring relationships apply when operating from the low
battery voltage. For high battery voltages (VBH) less than or
equal to the internal MTU reference threshold:
V RING = V BH + 4
(EQ. 12)
Loop Current
During LPS, the device will provide current to a load. The
current path is through resistors and switches, and will be
function of the off hook loop resistance (RLOOP). This
includes the off hook phone resistance and copper loop
resistance. The current available during LPS is determined
by Equation 13.
I LOOP = ( – 1 – ( – 49 ) ) ⁄ ( 600 + 600 + R LOOP )
(EQ. 13)
Internal current limiting of the standby switches will limit the
maximum current to 20mA.
Another loop current related parameter is longitudinal
current capability. The longitudinal current capability is
reduced to 10mARMS per pin. The reduction in longitudinal
current capability is a result of turning off the Tip and Ring
amplifiers.
On Hook Power Dissipation
The on hook power dissipation of the device during LPS is
determined by the operating voltages and quiescent currents
and is calculated using Equation 14.
P LPS = V BH × I BHQ + V BL × I BLQ + V CC × I CCQ
(EQ. 14)
600Ω
TIP AMP
TIP
RING
RING AMP
600Ω
MTU REF
FIGURE 2. LPS 2-WIRE INTERFACE CIRCUIT DIAGRAM
MTU Compliance
Maintenance Termination Unit or MTU compliance places
DC voltage requirements on the 2-wire terminals during idle
line conditions. The minimum idle voltage is 42.75V. The
high side of the MTU range is 56V. The voltage is expressed
as the difference between Tip and Ring.
The Tip voltage is held near ground through a 600Ω resistor
and switch. The Ring voltage is limited to a maximum of
-49V (by MTU REF) when operating from either the high or
low battery. A switch and 600Ω resistor connect the MTU
reference to the Ring terminal. When the high battery
9
The quiescent current terms are specified in the electrical
tables for each operating mode. Load power dissipation is
not a factor since this is an on hook mode. Some
applications may specify a standby current. The standby
current may be a charging current required for modern
telephone electronics.
Standby Current Power Dissipation
Any standby line current, ISLC , introduces an additional
power dissipation term PSLC . Equation 15 illustrates the
power contribution is zero when the standby line current is
zero.
P SLC = I SLC × ( V BH – 49 + 1 + I SLC x1200 )
(EQ. 15)
If the battery voltage is less than -49V (the MTU clamp is
off), the standby line current power contribution reduces to
Equation 16.
P SLC = I SLC × ( V BH + 1 + I SLC x1200 )
(EQ. 16)
Most applications do not specify charging current
requirements during standby. When specified, the typical
charging current may be as high as 5mA.
HC55183, HC55184
Forward Active
filter is set by the external capacitor CDC . The value of the
external capacitor should be 4.7μF.
The forward active mode (FA, 001) is the primary AC
transmission mode of the device. On hook transmission, DC
loop feed and voice transmission are supported during forward
active. Loop supervision is provided by either the switch hook
detector (E0 = 1) or the ground key detector (E0 = 0). The
device may be operated from either high or low battery for onhook transmission and low battery for loop feed.
On-Hook Transmission
The primary purpose of on hook transmission will be to
support caller ID and other advanced signalling features.
The transmission over load level while on hook is 3.5VPEAK .
When operating from the high battery, the DC voltages at Tip
and Ring are MTU compliant. The typical Tip voltage is -4V
and the Ring voltage is a function of the battery voltage for
battery voltages less than -60V as shown in Equation 17.
(EQ. 17)
V RING = V BH + 4
Loop supervision is provided by the switch hook detector at
the DET output. When DET goes low, the low battery should
be selected for DC loop feed and voice transmission.
Feed Architecture
The design implements a voltage feed current sense
architecture. The device controls the voltage across Tip and
Ring based on the sensing of load current. Resistors are
placed in series with Tip and Ring outputs to provide the
current sensing. The diagram below illustrates the concept.
VIN
RCS
-
+
RL
m = (ΔVTR/ΔIL) = 10kΩ
ILOOP (mA)
ILIM
FIGURE 4. DC FEED CHARACTERISTIC
The point on the y-axis labeled VTR(OC) is the open circuit
Tip to Ring voltage and is defined by the feed battery
voltage.
(EQ. 18)
V TR ( OC ) = V BL – 8
The curve of Figure 5 determines the actual loop current for
a given set of loop conditions. The loop conditions are
determined by the low battery voltage and the DC loop
impedance. The DC loop impedance is the sum of the
protection resistance, copper resistance (ohms/foot) and the
telephone off hook DC resistance.
ISC
IA
IB
ILIM
RA
VOUT
VTR(OC)
ILOOP (mA)
RB
Most applications will operate the device from low battery
while off hook. The DC feed characteristic of the device will
drive Tip and Ring towards half battery to regulate the DC
loop current. For light loads, Tip will be near -4V and Ring
will be near VVBL + 4V. The following diagram shows the DC
feed characteristic.
VTR , DC (V)
Overview
RC
-
2RP
RLOOP (Ω)
RKNEE
FIGURE 5. ILOOP vs RLOOP LOAD CHARACTERISTIC
+
KS
FIGURE 3. VOLTAGE FEED CURRENT SENSE DIAGRAM
By monitoring the current at the amplifier output, a negative
feedback mechanism sets the output voltage for a defined
load. The amplifier gains are set by resistor ratios (RA , RB ,
RC) providing all the performance benefits of matched
resistors. The internal sense resistor, RCS , is much smaller
than the gain resistors and is typically 20Ω for this device.
The feedback mechanism, KS , represents the amplifier
configuration providing the negative feedback.
The slope of the feed characteristic and the battery voltage
define the maximum loop current on the shortest possible
loop as the short circuit current ISC.
V TR ( OC ) – 2R P I LIM
I SC = I LIM + -----------------------------------------------------10K
(EQ. 19)
The term ILIM is the programmed current limit, 1760/RIL. The
line segment IA represents the constant current region of the
loop current limit function.
V TR ( OC ) – R LOOP I LIM
I A = I LIM + -------------------------------------------------------------10K
(EQ. 20)
DC Loop Feed
The feedback mechanism for monitoring the DC portion of
the loop current is the loop detector. A low pass filter is used
in the feedback to block voice band signals from interfering
with the loop current limit function. The pole of the low pass
10
The maximum loop impedance for a programmed loop
current is defined as RKNEE .
V TR ( OC )
R KNEE = -----------------------I LIM
(EQ. 21)
HC55183, HC55184
When RKNEE is exceeded, the device will transition from
constant current feed to constant voltage, resistive feed. The
line segment IB represents the resistive feed portion of the
load characteristic.
V TR ( OC )
I B = -----------------------R LOOP
(EQ. 22)
The AC feed back loop produces an echo at the VTX output
of the signal injected at VRX . The echo must be cancelled to
maintain voice quality. Most applications will use a summing
amplifier in the CODEC front end as shown below to cancel
the echo signal.
R
Voice Transmission
VRX
RA
VTX
RB
R
1:1
RX OUT
RF
-
RS
-IN
R
20
TIP
RING
-
VTX
-
TA
RS
-
+
R
0.75R
3R
-IN
3R
+
3R
R/2
CFB
8K
-
3R
VFB
VSA
FIGURE 6. AC SIGNAL TRANSMISSION MODEL
The gain of the transmit amplifier, set by RS , determines the
programmed impedance of the device. The capacitor CFB
blocks the DC component of the loop current. The ground
symbols in the model represent AC grounds, not actual DC
potentials.
The sense amp output voltage, VSA , as a function of Tip and
Ring voltage and load is calculated using Equation 23.
10
V SA = – ( V T – V R ) -----ZL
(EQ. 23)
The resistor ratio, RF /RB , provides the final adjustment for
the transmit gain, GTX . The transmit gain is calculated using
Equation 25.
⎛ R F⎞
G TX = – G 24 ⎜ --------⎟
⎝ R B⎠
The transmit amplifier provides the programmable gain
required for impedance synthesis. In addition, the output of
this amplifier interfaces to the CODEC transmit input. The
output voltage is calculated using Equation 24.
(EQ. 24)
Once the impedance matching components have been
selected using the design equations, the above equations
provide additional insight as to the expected AC node
voltages for a specific Tip and Ring load.
Transhybrid Balance
The final step in completing the impedance synthesis design
is calculating the necessary gains for transhybrid balance.
11
(EQ. 25)
Most applications set RF = RB , hence the device 2-wire to
4-wire equals the transmit gain. Typically RB is greater than
20kΩ to prevent loading of the device transmit output.
The resistor ratio, RF /RA , is determined by the transhybrid
gain of the device, G44 . RF is previously defined by the
transmit gain requirement and RA is calculated using
Equation 26.
RB
R A = ---------G 44
(EQ. 26)
Power Dissipation
The power dissipated by the device during on hook
transmission is strictly a function of the quiescent currents
for each supply voltage during Forward Active operation.
+ V BL × I BLQ + V CC × I CCQ
P FAQ = V BH × I
BHQ
RS
V VTX = – V SA ⎛ --------⎞
⎝ 8K⎠
CODEC
FIGURE 7. TRANSHYBRID BALANCE INTERFACE
1:1
+
TX IN
+2.4V
VRX
R
+
20
HC5518x
R
-
+
TA
+
The feedback mechanism for monitoring the AC portion of
the loop current consists of two amplifiers, the sense
amplifier (SA) and the transmit amplifier (TA). The AC
feedback signal is used for impedance synthesis. A detailed
model of the AC feed back loop is provided in the following.
(EQ. 27)
Off hook power dissipation is increased above the quiescent
power dissipation by the DC load. If the loop length is less
than or equal to RKNEE , the device is providing constant
current, IA , and the power dissipation is calculated using
Equation 28.
P FA ( IA ) = P FA ( Q ) + ( V BL xI A ) – ( R LOOP xI 2 A )
(EQ. 28)
If the loop length is greater than RKNEE , the device is
operating in the constant voltage, resistive feed region. The
power dissipated in this region is calculated using Equation 29.
P FA ( IB ) = P FA ( Q ) + ( V BL xI B ) – ( R LOOP xI 2 B )
(EQ. 29)
HC55183, HC55184
Since the current relationships are different for constant
current versus constant voltage, the region of device
operation is critical to valid power dissipation calculations.
Power Dissipation
Reverse Active
Ringing
Overview
Overview
The reverse active mode (RA, 011) provides the same
functionality as the forward active mode. On hook
transmission, DC loop feed and voice transmission are
supported. Loop supervision is provided by either the switch
hook detector (E0 = 1) or the ground key detector (E0 = 0).
The device may be operated from either high or low battery.
The ringing mode (RNG, 100) provides linear amplification to
support a variety of ringing waveforms. A programmable ring
trip function provides loop supervision and auto disconnect
upon ring trip. The device is designed to operate from the
high battery during this mode.
During reverse active the Tip and Ring DC voltage
characteristics exchange roles. That is, Ring is typically 4V
below ground and Tip is typically 4V more positive than
battery. Otherwise, all feed and voice transmission
characteristics are identical to forward active.
The device provides linear amplification to the signal applied
to the ringing input, VRS . The differential ringing gain of the
device is 80V/V. The circuit model for the ringing path is
shown in the following figure.
The power dissipation equations for forward active operation
also apply to the reverse active mode.
Architecture
R
Silent Polarity Reversal
Changing from forward active to reverse active or vice versa
is referred to as polarity reversal. Many applications require
slew rate control of the polarity reversal event. Requirements
range from minimizing cross talk to protocol signalling.
TIP
The internal circuitry used to set the polarity reversal time is
shown in the following.
I1
75kΩ
POL
CPOL
I2
FIGURE 8. REVERSAL TIMING CONTROL
During forward active, the current from source I1 charges
the external timing capacitor CPOL and the switch is open.
The internal resistor provides a clamping function for
voltages on the POL node. During reverse active, the switch
closes and I2 (roughly twice I1) pulls current from I1 and the
timing capacitor. The current at the POL node provides the
drive to a differential pair which controls the reversal time of
the Tip and Ring DC voltages.
Δtime
C POL = ---------------75000
(EQ. 30)
Where Δtime is the required reversal time. Polarized
capacitors may be used for CPOL . The low voltage at the
POL pin and minimal voltage excursion ±0.75V, are well
suited to polarized capacitors.
12
R/8
-
-
+
+
5:1
RING
The device uses an external low voltage capacitor, CPOL , to
set the reversal time. Once programmed, the reversal time
will remain nearly constant over various load conditions. In
addition, the reversal timing capacitor is isolated from the AC
loop, therefore loop stability is not impacted.
20
20
+
-
VRS
800K
+ VBH
2
R
FIGURE 9. LINEAR RINGING MODEL
The voltage gain from the VRS input to the Tip output is
40V/V. The resistor ratio provides a gain of 8 and the current
mirror provides a gain of 5. The voltage gain from the VRS
input to the Ring output is -40V/V. The equations for the Tip
and Ring outputs during ringing are provided below.
V BH
V T = ----------- + ( 40 × VRS )
2
(EQ. 31)
V BH
V R = ----------- – ( 40 × VRS )
2
(EQ. 32)
When the input signal at VRS is zero, the Tip and Ring
amplifier outputs are centered at half battery. The device
provides auto centering for easy implementation of
sinusoidal ringing waveforms. Both AC and DC control of the
Tip and Ring outputs is available during ringing. This feature
allows for DC offsets as part of the ringing waveform.
Ringing Input
The ringing input, VRS , is a high impedance input. The high
impedance allows the use of low value capacitors for AC
coupling the ring signal. The VRS input is enabled only
during the ringing mode, therefore a free running oscillator
may be connected to VRS at all times.
When operating from a battery of -75V, each amplifier, Tip
and Ring, will swing a maximum of 70VP-P . Hence, the
maximum signal swing at VRS to achieve full scale ringing is
HC55183, HC55184
approximately 2.4VP-P . The low signal levels are compatible
with the output voltage range of the CODEC. The digital
nature of the CODEC ideally suits it for the function of
programmable ringing generator. See Applications.
Logic Control
Ringing patterns consist of silent intervals. The ringing to
silent pattern is called the ringing cadence. During the silent
portion of ringing, the device can be programmed to any
other operating mode. The most likely candidates are low
power standby or forward active. Depending on system
requirements, the low or high battery may be selected.
Loop supervision is provided with the ring trip detector. The ring
trip detector senses the change in loop current when the phone
is taken off hook. The loop detector full wave rectifies the
ringing current, which is then filtered with external components
RRT and CRT. The resistor RRT sets the trip threshold and the
capacitor CRT sets the trip response time. Most applications will
require a trip response time less than 150ms.
Three very distinct actions occur when the devices detects a
ring trip. First, the DET output is latched low. The latching
mechanism eliminates the need for software filtering of the
detector output. The latch is cleared when the operating
mode is changed externally. Second, the VRS input is
disabled, removing the ring signal from the line. Third, the
device is internally forced to the forward active mode.
Power Dissipation
For sinusoidal waveforms, the average current, IAVG, is
defined in Equation 36.
V RMS × 2
2
I AVG = ⎛ ---⎞ -----------------------------------------⎝ π⎠ Z
+R
REN
(EQ. 36)
LOOP
The silent interval power dissipation will be determined by
the quiescent power of the selected operating mode.
Forward Loop Back
Overview
The forward loop back mode (FLB, 101) provides test
capability for the device. An internal signal path is enabled
allowing for both DC and AC verification. The internal 600Ω
terminating resistor has a tolerance of ±20%. The device is
intended to operate from only the low battery during this
mode.
Architecture
When the forward loop back mode is initiated internal
switches connect a 600Ω load across the outputs of the Tip
and Ring amplifiers.
TIP
TIP AMP
600Ω
RING AMP
RING
The power dissipation during ringing is dictated by the load
driving requirements and the ringing waveform. The key to valid
power calculations is the correct definition of average and RMS
currents. The average current defines the high battery supply
current. The RMS current defines the load current.
The cadence provides a time averaging reduction in the
peak power. The total power dissipation consists of ringing
power, Pr, and the silent interval power, Ps .
tr
ts
P RNG = P r × -------------- + P s × -------------tr + ts
tr + ts
(EQ. 33)
The terms tR and tS represent the cadence. The ringing
interval is tR and the silent interval is tS . The typical cadence
ratio tR :tS is 1:2.
The quiescent power of the device in the ringing mode is
defined in Equation 34.
P r ( Q ) = V BH × I BHQ + V BL × I BLQ + V CC × I CCQ
(EQ. 34)
The total power during the ringing interval is the sum of the
quiescent power and loading power:
2
V RMS
P r = P r ( Q ) + V BH × I AVG – -----------------------------------------Z
+R
REN
13
LOOP
(EQ. 35)
FIGURE 10. FORWARD LOOP BACK INTERNAL TERMINATION
DC Verification
When the internal signal path is provided, DC current will
flow from Tip to Ring. The DC current will force DET low,
indicating the presence of loop current. In addition, the ALM
output will also go low. This does not indicate a thermal
alarm condition. Rather, proper logic operation is verified in
the event of a thermal shutdown. In addition to verifying
device functionality, toggling the logic outputs verifies the
interface to the system controller.
AC Verification
The entire AC loop of the device is active during the forward
loop back mode. Therefore a 4-wire to 4-wire level test
capability is provided. Depending on the transhybrid balance
implementation, test coverage is provided by a one or two
step process.
System architectures which cannot disable the transhybrid
function would require a two step process. The first step
would be to send a test tone to the device while on hook and
not in forward loop back mode. The return signal would be
the test level times the gain RF /RA of the transhybrid
amplifier. Since the device would not be terminated,
cancellation would not occur. The second step would be to
program the device to FLB and resend the test tone. The
HC55183, HC55184
return signal would be much lower in amplitude than the first
step, indicating the device was active and the internal
termination attenuated the return signal.
Thermal Shutdown
System architectures which disable the transhybrid function
would achieve test coverage with a signal step. Once the
transhybrid function is disable, program the device for FLB
and send the test tone. The return signal level is determined
by the 4-wire to 4-wire gain of the device.
In the event the safe die temperature is exceeded, the ALM
output will go low and DET will go high and the part will
automatically shut down. When the device cools, ALM will
go high and DET will reflect the loop status. If the thermal
fault persists, ALM will go low again and the part will shut
down. Programming power denial will permanently
shutdown the device and stop the self cooling cycling.
Tip Open
Battery Switching
Overview
Overview
The tip open mode (110) is intended for compatibility for
PBX type interfaces. Used during idle line conditions, the
device does not provide transmission. Loop supervision is
provided by either the switch hook detector (E0 = 1) or the
ground key detector (E0 = 0). The ground key detector will
be used in most applications. The device may be operated
from either high or low battery.
The integrated battery switch selects between the high
battery and low battery. The battery switch is controlled
with the logic input BSEL. When BSEL is a logic high, the
high battery is selected and when a logic low, the low
battery is selected. All operating modes of the device will
operate from high or low battery except forward loop back.
Functionality
The logic control is independent of the operating mode
decode. Independent logic control provides the most
flexibility and will support all application configurations.
During tip open operation, the Tip amplifier is disabled and
the Ring amplifier is enabled. The minimum Tip impedance
is 30kΩ. The only active path through the device will be the
Ring amplifier.
In keeping with the MTU characteristics of the device, Ring
will not exceed -56.5V when operating from the high battery.
Though MTU does not apply to tip open, safety requirements
are satisfied.
On Hook Power Dissipation
The on hook power dissipation of the device during tip open
is determined by the operating voltages and quiescent
currents and is calculated using Equation 37.
P TO = V BH × I BHQ + V BL × I BLQ + V CC × I CCQ
(EQ. 37)
The quiescent current terms are specified in the electrical
tables for each operating mode. Load power dissipation is
not a factor since this is an on hook mode.
Functionality
When changing device operating states, battery switching
should occur simultaneously with or prior to changing the
operating mode. In most cases, this will minimize overall
power dissipation and prevent glitches on the DET output.
The only external component required to support the battery
switch is a diode in series with the VBH supply lead. In the
event that high battery is removed, the diode allows the
device to transition to low battery operation.
Low Battery Operation
All off hook operating conditions should use the low battery.
The prime benefit will be reduced power dissipation. The
typical low battery for the device is -24V. However this may
be increased to support longer loop lengths or high loop
current requirements. Standby conditions may also operate
from the low battery if MTU compliance is not required,
further reducing standby power dissipation.
Power Denial
High Battery Operation
Overview
Other than ringing, the high battery should be used for
standby conditions which must provide MTU compliance.
During standby operation the power consumption is typically
less than 50mW with -75V battery. If ringing requirements do
not require full 75V operation, then a lower battery will result
in lower standby power.
The power denial mode (111) will shutdown the entire device
except for the logic interface. Loop supervision is not
provided. This mode may be used as a sleep mode or to
shut down in the presence of a persistent thermal alarm.
Switching between high and low battery will have no effect
during power denial.
Functionality
During power denial, both the Tip and Ring amplifiers are
disabled, representing high impedances. The voltages at
both outputs are near ground.
14
High Voltage Decoupling
The 75V rating of the device will require a capacitor of higher
voltage rating for decoupling. Suggested decoupling values
for all device pins are 0.1μF. Standard surface mount
ceramic capacitors are rated at 100V. For applications
driven at low cost and small size, the decoupling scheme
shown below could be implemented.
HC55183, HC55184
0.22μ
Since the device provides the ringing waveform, the relay
functions which may be supported include subscriber
disconnect, test access or line interface bypass. An external
snubber diode is not required when using the uncommitted
switch as a relay driver.
0.22μ
VBL
VBH
HC5518X
Test Load
FIGURE 11. ALTERNATE DECOUPLING SCHEME
As with all decoupling schemes, the capacitors should be as
close to the device pins as physically possible.
Uncommitted Switch
The switch may be used to connect test loads across Tip
and Ring. The test loads can provide external test
termination for the device. Proper connection of the
uncommitted switch to Tip and Ring is shown in the
following.
Overview
The uncommitted switch is a three terminal device designed
for flexibility. The independent logic control input, SWC,
allows switch operation regardless of device operating
mode. The switch is activated by a logic low. The positive
and negative terminals of the device are labeled SW+ and
SW- respectively.
Relay Driver
The uncommitted switch may be used as a relay driver by
connecting SW+ to the relay coil and SW- to ground. The
switch is designed to have a maximum on voltage of 0.6V
with a load current of 45mA.
+5V
RELAY
SW+
SW-
SWC
FIGURE 12. EXTERNAL RELAY SWITCHING
15
TIP
RING
TEST
LOAD
SW+
SW-
SWC
FIGURE 13. TEST LOAD SWITCHING
The diode in series with the test load blocks current from
flowing through the uncommitted switch when the polarity of
the Tip and Ring terminals are reversed. In addition to the
reverse active state, the polarity of Tip and Ring are
reversed for half of the ringing cycle. With independent logic
control and the blocking diode, the uncommitted switch may
be continuously connected to the Tip and Ring terminals.
HC55183, HC55184
Basic Application Circuits
.
TABLE 2. BASIC APPLICATION CIRCUIT COMPONENT LIST
COMPONENT
VALUE
TOLERANCE
RATING
U1 - Ringing SLIC
HC5518x
N/A
N/A
RRT
20kΩ
1%
0.1W
RSH
49.9kΩ
1%
0.1W
RIL
71.5kΩ
1%
0.1W
RS
210kΩ
1%
0.1W
CRX , CRS , CTX , CRT , CPOL , CFB
0.47μF
20%
10V
CDC
4.7μF
20%
10V
CPS1
0.1μF
20%
>100V
CPS2 , CPS3
0.1μF
20%
100V
D1
1N400X type with breakdown > 100V.
RP1 , RP2
Protection resistor values are application dependent and will be determined by protection
requirements. Standard applications will use ≥ 35Ω per side.
Design Parameters: Ring Trip Threshold = 90mAPEAK , Switch Hook Threshold = 12mA, Loop Current Limit = 24.6mA, Synthesize Device
Impedance = 210kΩ/400 = 525Ω, with 39Ω protection resistors, impedance across Tip and Ring terminals = 603Ω. Where applicable, these
component values apply to the Basic Application Circuits for the HC55183 and HC55184. Pins not shown in the Basic Application Circuit are no
connect (NC) pins.
CPS1
CPS1
CPS2
VCC
VBL
TIP
U1
HC55183
RING
RP2
VBH
RRT
VCC
CRX
CTX
RRT
VFB
RD
ILIM
CDC
F2
DET
CDC
VCC
CPOL
BGND
FIGURE 14. HC55183 BASIC APPLICATION CIRCUIT
16
-IN
CFB
BSEL
F0
F1
CDC
POL
ALM
AGND
CTX
VTX
E0
ILIM
F1
CRS
VRS
VFB
RIL
F0
CDC
RTD
RD
E0
CRX
RS
RSH
BSEL
RIL
VBH
CRT
CFB
RSH
U1
HC55184
RING
RP2
-IN
RTD
TIP
VTX
RS
VBL
VRX
RP1
CRS
VRS
CRT
D1
CPS3
VRX
RP1
VCC
CPS2
D1
CPS3
F2
DET
ALM
AGND
BGND
FIGURE 15. HC55184 BASIC APPLICATION CIRCUIT
HC55183, HC55184
Additional Application Diagrams
Reducing Overhead Voltages
The transmission overhead voltage of the device is
internally set to 4V per side. The overhead voltage may be
reduced by injecting a negative DC voltage on the receive
input using a voltage divider (Figure 16). Accordingly, the
2-wire port overload level will decrease the same amount
as the injected offset.
R2 C
RX
160kΩ
VD
VRX
FROM
CODEC
R1
1:1
HC5518X
VBL
applications the synthesized device impedance (i.e., 600Ω)
will not match the 200Ω teletax impedance. The gain set by
RT cancels the impedance matching feedback with respect
to the teletax injection point. Therefore the device appears
as a low impedance source for teletax. The resistor RT is
calculated using the following equation.
200
R T = ------------------------------------------------------------------- × R S
200 + 2 × R P + ( R S ⁄ 400 )
The signal level across a 200Ω load will be twice the injected
teletax signal level. As the teletax level at VTX will equal the
injection level, set RC = RB for cancellation. The value of RB
is based on the voice band transhybrid balance
requirements. The connection of the teletax source to the
transhybrid amplifier should be AC coupled to allow proper
biasing of the transhybrid amplifier input
TA
FIGURE 16. EXTERNAL OVERHEAD CONTROL
CFB
VFB
RT
CODEC Ringing Generation
Maximum ringing amplitudes of the device are achieved with
signal levels approximately 2.4VP-P. Therefore the low pass
receive output of the CODEC may serve as the low level ring
generator. The ringing input impedance of 480kΩ minimum
should not interfere with CODEC drive capability. A single
external capacitor is required to AC coupled the ringing
signal from the CODEC. The circuit diagram for CODEC
ringing is shown below.
-IN
RF
RB
RS
-
+
VTX
RC
CODEC
FIGURE 18. TELETAX SIGNALLING
Ringing With DC Offsets
The balanced ringing waveform consists of zero DC offset
between the Tip and Ring terminals. However, the linear
amplifier architecture provides control of the DC offset during
ringing. The DC gain is the same as the AC gain, 40V/V per
amplifier. Positive DC offsets applied directly to the ringing
input will shift both Tip and Ring away from half battery
towards ground and battery respectively. A voltage divider
on the ringing input may be used to generate the offset
(Figure 19). The reference voltage, VREF, can be either the
CODEC 2.4V reference voltage or the 5V supply.
R2
-
+
160kΩ
VRS
480K
VRX
RX OUT
1:1
VD
CRS
FROM
RING GEN.
R1
HC5518X
VREF
-
+
480K
TX IN
+2.4V
TELETAX
SOURCE
(EQ. 38)
With a low battery voltage -24V and a divider voltage of
-0.5V, the Tip to Ring voltage is 17V. As a result, the
overhead voltage is reduced from 8V to 7V and the overload
level will decrease from 3.5VPEAK to 3.0VPEAK.
-
V T – R = V BL – 8 – ( 2 × V D )
+
The divider shunt resistance is the parallel combination of
the internal 160kΩ resistor and the external R2 . The sum of
R1 and R2 should be greater than 500kΩ to minimize the
additional power dissipation of the divider. The DC gain
relationship from the divider voltage, VD , to the Tip and Ring
outputs is shown below.
(EQ. 39)
FIGURE 19. EXTERNAL OVERHEAD CONTROL
VRS
CODEC
HC5518X
FIGURE 17. CODEC RINGING INTERFACE
Implementing Teletax Signalling
A resistor, RT, is required at the -IN input of the device for
injecting the teletax signal (Figure 17). For most
17
An offset during ringing of 30V, would require a DC shift of
15V at Tip and 15V at Ring. The DC offset would be created
by a +0.375V (VD) at the VRS input. The divider resistors
should be selected to minimize the value of the AC coupling
capacitor CRS and the loading of the ring generator and
voltage reference. The ringing input impedance should also
be accounted for in divider resistor calculations.
HC55183, HC55184
Pin Descriptions
PLCC
SYMBOL
DESCRIPTION
1
TIP
2
BGND
3
VBL
Low battery supply connection.
4
VBH
High battery supply connection for the most negative battery.
5, 6, 7, 16
NC
No connect
8
F2
Mode control input - MSB. F2-F0 for the TTL compatible parallel control interface for controlling the various modes of
operation of the device.
9
F1
Mode control input.
10
F0
Mode control input.
11
E0
Detector Output Selection Input. This TTL input controls the multiplexing of the SHD (E0 = 1) and GKD (E0 = 0) comparator
outputs to the DET output based upon the state at the F2-F0 pins (see the Device Operating Modes table shown on page 2).
12
DET
Detector Output - This TTL output provides on-hook/off-hook status of the loop based upon the selected operating mode.
The detected output will either be switch hook, ground key or ring trip (see the Device Operating Modes table shown on
page 2).
13
ALM
Thermal Shutdown Alarm. This pin signals the internal die temperature has exceeded safe operating temperature
(approximately 175°C) and the device has been powered down automatically.
14
AGND
Analog ground reference. This pin should be externally connected to BGND.
15
BSEL
Selects between high and low battery, with a logic “1” selecting the high battery and logic “0” the low battery. This pin is a
no connect (NC) on the HC55180.
17
POL
External capacitor on this pin sets the polarity reversal time. This pin is a no connect on the HC55183.
18
VRS
Ringing Signal Input - Analog input for driving 2-wire interface while in Ring Mode.
19
VRX
Analog Receive Voltage - 4-wire analog audio input voltage. AC couples to CODEC.
20
VTX
Transmit output voltage - Output of impedance matching amplifier, AC couples to CODEC.
21
VFB
Feedback voltage for impedance matching. This voltage is scaled to accomplish impedance matching.
22
-IN
23
VCC
Positive voltage power supply, usually +5V.
24
CDC
DC Biasing Filter Capacitor - Connects between this pin and VCC.
25
RTD
Ring trip filter network.
26
ILIM
Loop Current Limit programming resistor.
27
RD
Switch hook detection threshold programming resistor.
28
RING
TIP power amplifier output.
Battery Ground - To be connected to zero potential. All loop current and longitudinal current flow from this ground. Internally
separate from AGND but it is recommended that it is connected to the same potential as AGND.
Impedance matching amplifier summing node.
RING power amplifier output.
18
HC55183, HC55184
Plastic Leaded Chip Carrier Packages (PLCC)
0.042 (1.07)
0.048 (1.22)
PIN (1) IDENTIFIER
N28.45 (JEDEC MS-018AB ISSUE A)
0.042 (1.07)
0.056 (1.42)
0.004 (0.10)
C
0.025 (0.64)
R
0.045 (1.14)
0.050 (1.27) TP
C
L
D2/E2
E1 E
C
L
D2/E2
VIEW “A”
0.020 (0.51)
MIN
A1
A
D1
D
28 LEAD PLASTIC LEADED CHIP CARRIER PACKAGE
INCHES
MILLIMETERS
SYMBOL
MIN
MAX
MIN
MAX
NOTES
A
0.165
0.180
4.20
4.57
-
A1
0.090
0.120
2.29
3.04
-
D
0.485
0.495
12.32
12.57
-
D1
0.450
0.456
11.43
11.58
3
D2
0.191
0.219
4.86
5.56
4, 5
E
0.485
0.495
12.32
12.57
-
E1
0.450
0.456
11.43
11.58
3
E2
0.191
0.219
4.86
5.56
4, 5
N
28
28
6
Rev. 2 11/97
SEATING
-C- PLANE
0.020 (0.51) MAX
3 PLCS
0.026 (0.66)
0.032 (0.81)
0.013 (0.33)
0.021 (0.53)
0.025 (0.64)
MIN
0.045 (1.14)
MIN
VIEW “A” TYP.
NOTES:
1. Controlling dimension: INCH. Converted millimeter dimensions are
not necessarily exact.
2. Dimensions and tolerancing per ANSI Y14.5M-1982.
3. Dimensions D1 and E1 do not include mold protrusions. Allowable
mold protrusion is 0.010 inch (0.25mm) per side. Dimensions D1
and E1 include mold mismatch and are measured at the extreme
material condition at the body parting line.
4. To be measured at seating plane -C- contact point.
5. Centerline to be determined where center leads exit plastic body.
6. “N” is the number of terminal positions.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
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
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19
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