PIN DESCRIPTIONS
Pin Names
ACO
AGND
ALM
A(TIP)
BGND
B(RING)
C1, C2, C3
CAS
CS
D1
DA
DB
DET
HPA
HPB
NC
RD
RDC
RINGOUT
RSN
Input
Gnd
Output
Output
Gnd
Output
Input
Capacitor
Input
Input
Input
Input
Output
Capacitor
Capacitor
—
Resistor
Resistor
Output
Input
Type
Description
Overvoltage Alarm. Input from external resistor allows detection of positive overvoltages
on the line. Detection forces ALM and DET Low.
Analog ground
Alarm. A logic Low indicates that a fault detector has been activated. Faults detected
include thermal overload, ACO, and B to ground faults.
Output of A(TIP) power amplifier
Battery (power) ground
Output of B(RING) power amplifier
SLIC control pins. C3 is MSB and C1 is LSB. TTL compatible.
Anti-saturation pin for capacitor to filter reference voltage when operating in anti-saturation
region.
Logic input to enable/disable the ALM and DET outputs. A logic Low enables the outputs.
A logc High disables the outputs.
D1 controls the relay driver RYOUT1. A logic High on D1 activates the RYOUT1 relay
driver. TTL compatible.
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 C2 and C3
select the detector. Open-collector with a built-in 15 kΩ pull-up resistor.
High-Pass Filter Capacitor. A(TIP) side of high-pass filter capacitor.
High-Pass Filter Capacitor. B(RING) side of high-pass filter capacitor.
No connect. Pin not internally connected.
Detector resistor. Detector threshold set and filter pin.
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).
Ring Signal Driver. Open-collector driver with emitter internally connected to BGND.
The metallic current (AC and DC) between A(TIP) and B(RING) is equal to 500 x the
current into this pin. The networks that program receive gain, two-wire impedance, and
feed current all connect to this node.
Relay Driver. Open-collector driver with emitter internally connected to BGND.
Thermal Management. External resistor connects between this pin and VBAT to offload
power from SLIC.
Battery supply and connection to substrate
This is an Legerity-reserved pin and must always be connected to the VBAT pin.
+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.
RYOUT1
TMG
VBAT
VBREF
VCC
VTX
Output
—
Battery
—
Power
Output
4
Le7925 Data Sheet
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
