am7945 Advanced Micro Devices, am7945 Datasheet - Page 4

• Manufacturer Part Number: am7945
• Description: Subscriber Line Interface Circuit
• Manufacturer: Advanced Micro Devices

PIN DESCRIPTIONS
4
AGND/DGND
A(TIP)
BGND
B(RING)
C3–C1
CAS
DA
DB
DET
E0
E1
HPA
HPB
RD
RDC
RINGOUT
RSN
TMG
TP
VBAT
VCC
VEE
VTX
Pin Names
Gnd
Output
Gnd
Output
Input
Capacitor
Input
Input
Output
Input
Input
Capacitor
Capacitor
Resistor
Resistor
Output
Input
—
Thermal
Battery
Power
Power
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 k
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
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.
Am7945 Data Sheet
pull-up resistor.
Description
RDC
is negative