Am7945
Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
s
Programmable constant-current feed
s
Current gain = 200
s
Programmable loop-detect threshold
s
Low power Standby state
s
Ground-key detector
s
Tip Open state for ground-start lines
s
–19 V to –56.5 V battery operation
s
On-chip Thermal Management (TMG) feature
s
Two-wire impedance set by single external
impedance
s
On-hook transmission
s
On-chip ring relay driver and relay snubber
circuit
s
Ideal for low cost PABX and key telephone
systems
BLOCK DIAGRAM
TMG
A(TIP)
Ring Relay
Driver
RINGOUT
C1
C2
HPA
Two-Wire
Interface
HPB
Signal
Transmission
B(RING)
Off-Hook
Detector
Ground-Key
Detector
Input Decoder
and Control
C3
E0
E1
DET
RSN
VTX
RD
Power-Feed
Controller
DA
DB
VBAT
BGND
Ring-Trip
Detector
RDC
CAS
VCC
VEE
AGND/DGND
Publication#
18408
Rev:
D
Amendment:
/0
Issue Date:
October 1999
ORDERING INFORMATION
Standard Products
AMD standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed
by a combination of the elements below.
Am7945
J
C
TEMPERATURE RANGE
C = Commercial (0°C to 70°C)*
PACKAGE TYPE
J = 32-pin Plastic Leaded Chip Carrier (PL 032)
DEVICE NUMBER/DESCRIPTION
Am7945
Subscriber Line Interface Circuit
Valid Combinations
Am7945
JC
Valid Combinations
Valid Combinations list configurations planned to
be supported in volume for this device. Consult
the local AMD sales office to confirm availability
of specific valid combinations and to check on newly
released combinations, and to obtain additional
data on AMD’s standard military grade products.
Note:
* Functionality of the device from 0°C to +70°C is guaranteed by production testing. Performance from –40°C to +85°C is
guaranteed by characterization and periodic sampling of production units.
2
Am7945 Data Sheet
CONNECTION DIAGRAM
Top View
32-Pin PLCC
B(RING)
BGND
A(TIP)
31
VCC
NC
NC
4
TP
RINGOUT
NC
TMG
VBAT
C3
E1
C2
DET
5
6
7
8
9
10
11
12
13
14
C1
3
2
1
32
30
29
28
27
26
25
24
23
22
21
TP
DA
RD
HPB
NC
HPA
VTX
VEE
RSN
15
NC
16
E0
17 18
NC
CAS
19
RDC
20
AGND/DGND
Notes:
1. Pin 1 is marked for orientation.
2. TP is a thermal conduction pin tied to substrate.
3. NC = No Connect
SLIC Products
DB
3
PIN DESCRIPTIONS
Pin Names
AGND/DGND
A(TIP)
BGND
B(RING)
C3–C1
CAS
DA
DB
DET
Gnd
Output
Gnd
Output
Input
Capacitor
Input
Input
Output
Type
Analog and digital ground
Output of A(TIP) power amplifier
Battery (power) ground
Output of B(RING) power amplifier
Decoder. TTL compatible. C3 is MSB and C1 is LSB.
Anti-saturation pin for capacitor to filter reference voltage when operating in anti-saturation
region.
Ring-Trip Negative. Negative input to ring-trip comparator.
Ring-Trip Positive. Positive input to ring-trip comparator.
Switchhook Detector. When enabled, a logic Low indicates the selected detector is tripped.
The detect condition is selected by the logic inputs (C3–C1, E0, E1). The output is open-
collector with a built-in 15 kΩ pull-up resistor.
Ground-Key Enable. A logic High enables DET. A logic Low disables DET (PLCC only).
Ground-Key Enable. E1 = Low connects the ground-key or ring-trip detector to DET. E1 =
High connects the off-hook or ring-trip detector to DET (PLCC only).
High-Pass Filter Capacitor. A(TIP) side of high-pass filter capacitor.
High-Pass Filter Capacitor. B(RING) side of high-pass filter capacitor.
Detect Resistor. Threshold modification and filter point for the off-hook detector.
DC Feed Resistor. Connection point for the DC feed current programming network. The
other end of the network connects to the receiver summing node (RSN). V
RDC
is negative
for normal polarity and positive for reverse polarity.
Ring Relay Driver. Open-collector driver with emitter internally connected to BGND.
Receive Summing Node. The metallic current (both AC and DC) between A(TIP) and
B(RING) is equal to 200 times the current into this pin. Networks that program receive gain,
two-wire impedance, and feed resistance all connect to this node.
Thermal Management. Connect an external resistor between this pin and the VBAT pin to
reduce on-chip power dissipation in the normal polarity, Active state only. See Table 2.
Thermal pin. Connection for heat dissipation. Internally connected to substrate (QBAT).
Leave as open circuit or connected to QBAT. In both cases, the TP pins can connect to an
area of copper on the board to enhance heat dissipation.
Battery supply
+5 V power supply
–5 V power supply
Transmit Audio. This output is a unity gain version of the A(TIP) and B(RING) metallic
voltage. VTX also sources the two-wire input impedance programming network.
Description
E0
E1
HPA
HPB
RD
RDC
Input
Input
Capacitor
Capacitor
Resistor
Resistor
RINGOUT
RSN
Output
Input
TMG
TP
—
Thermal
VBAT
VCC
VEE
VTX
Battery
Power
Power
Output
4
Am7945 Data Sheet
ABSOLUTE MAXIMUM RATINGS
Storage temperature . . . . . . . . . . . . –55°C to +150°C
With respect to AGND/DGND:
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . .–0.4 V to +7.0 V
V
EE
. . . . . . . . . . . . . . . . . . . . . . . . . . .+0.4 V to –7.0 V
V
BAT
Continuous . . . . . . . . . . . . . . . . . . +0.4 V to –70 V
10 ms . . . . . . . . . . . . . . . . . . . . . . +0.4 V to –75 V
BGND. . . . . . . . . . . . . . . . . . . . . . . . . . . .+3 V to –3 V
A(TIP) or B(RING) with respect to BGND:
Continuous . . . . . . . . . . . . . . . . . . . .–70 V to +1 V
10 ms (f = 0.1 Hz) . . . . . . . . . . . . . . . –70 V to +5 V
1 ms (f = 0.1 Hz) . . . . . . . . . . . . . . . . –80 V to +8 V
10 µs (f = 0.1 Hz) . . . . . . . . . . . . .–100 V to +12 V
Current from A(TIP) or B(RING). . . . . . . . . . ±150 mA
Current from TMG . . . . . . . . . . . . . . . . . . . . . 100 mA
Voltage on RINGOUT:
During transient . . . . . . . . . . . . . . BGND to +10 V
During steady state . . . . . . . . . . . . . BGND to +7 V
Current through relay drivers . . . . . . . . . . . . . . 60 mA
DA and DB inputs
Voltage on ring-trip inputs . . . . . . . . . . .V
BAT
to 0 V
Current into ring-trip inputs . . . . . . . . . . . . ±10 mA
C3–C1, E0, E1
to AGND/DGND . . . . . . . . . –0.4 V to V
CC
+ 0.4 V
Maximum power dissipation, T
A
= 85°C
No heat sink (See note):
In 32-pin PLCC package. . . . . . . . . . . . . . . . 1.4 W
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
θ
JA
In 32-pin PLCC package. . . . . . . . . . . .43°C/W typ
Note:
Thermal limiting circuitry on chip will shut down the cir-
cuit at a junction temperature of about 165°C. The device
should never be exposed to this temperature. Operation above
145°C junction temperature may degrade device reliability.
See the SLIC Packaging Considerations for more information.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent device failure. Functionality at or above
these limits is not implied. Exposure to Absolute Maximum
Ratings for extended periods may affect device reliability.
OPERATING RANGES
Commercial (C) Devices
Ambient temperature . . . . . . . . . . . . . . 0°C to +70°C*
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . .4.75 V to 5.25 V
V
EE
. . . . . . . . . . . . . . . . . . . . . . . . .–4.75 V to –5.25 V
V
BAT
. . . . . . . . . . . . . . . . . . . . . . . . . –19 V to –56.5 V
AGND/DGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V
BGND with respect to
AGND/DGND . . . . . . . . . . . –100 mV to +100 mV
Load resistance on VTX to GND . . . . . . . . 10 k
Ω
min
The Operating Ranges define those limits over which the
functionality of the device is guaranteed by production testing.
* Functionality of the device from 0°C to +70°C is guaranteed
by production testing. Performance from –40°C to +85°C is
guaranteed by characterization and periodic sampling of pro-
duction units.
SLIC Products
5
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