am79574 Advanced Micro Devices, am79574 Datasheet - Page 4

• Manufacturer Part Number: am79574
• Description: Subscriber Line Interface Circuit
• Manufacturer: Advanced Micro Devices

PIN DESCRIPTIONS
4
AGND
A(TIP)
BGND
B(RING)
C3–C1
C4
CHCLK
CHS
DA
DB
DET
DGND
E0
E1
HPA
HPB
L
QBAT
RD
RDC
RINGOUT
RSN
TESTOUT
TP
VBAT
VCC
VEE
VREG
VTX
Pin Names
Gnd
Output
Gnd
Output
Input
Input
Input
Input
Input
Input
Output
Gnd
Input
Input
Capacitor High-pass filter capacitor. A(TIP) side of high-pass filter capacitor.
Capacitor High-pass filter capacitor. B(RING) side of high-pass filter capacitor.
Output
Battery
Resistor
Resistor
Output
Input
Output
Thermal
Battery
Power
Power
Input
Output
Type
Analog (quiet) 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.
Test relay driver command. TTL compatible. Logic Low enables the driver.
Chopper clock. Input to switching regulator (TTL compatible). Freq = 256 kHz (Nominal).
Chopper stabilization. Connection for external stabilization components.
Ring-trip negative. Negative input to ring-trip comparator.
Ring-trip positive. Positive input to ring-trip comparator.
Detector. Logic Low indicates that the selected detector is tripped. Logic inputs C3–C1, E1, and E0
select the detector. Open-collector with a built-in 15 k pull-up resistor.
Digital ground
A logic High enables DET. A logic Low disables DET.
E1 = High connects the ground-key detector to DET, and E1 = Low connects the off-hook or ring-trip
detector to DET.
Switching Regulator Power Transistor. Connection point for filter inductor and anode of catch diode.
Has up to 60 V of pulse waveform on it and must be isolated from sensitive circuits. Keep the diode
connections short because of the high currents and high di/dt.
Filtered battery supply for the signal processing circuits.
Detector resistor. Threshold modification and filter point for the off-hook detector.
DC feed resistor. Connection point for the DC feed current programming network, which also
connects to the Receiver Summing Node (RSN). V
for reverse polarity.
Ring relay driver. Sourcing from BGND with internal diode to QBAT.
The metallic current (AC and DC) between A(TIP) and B(RING) = 1000 x the current into this pin. The
networks that program receive gain, two-wire impedance, and feed resistance all connect to this
node. This node is extremely sensitive. Route the 256 kHz chopper clock and switch lines away from
the RSN node.
Test relay driver. Source from BGND with internal diode to QBAT.
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. Connected through an external protection diode.
+5 V power supply.
Regulated voltage. Provides negative power supply for power amplifiers, connection point for
inductor, filter capacitor, and chopper stabilization.
Transmit Audio. Unity gain version of the A(TIP) and B(RING) metallic voltage. VTX also sources the
two-wire input impedance programming network.
–5 V power supply.
Am79574 Data Sheet
Description
RDC
is negative for normal polarity and positive