Le7920
Data Sheet
PIN DESCRIPTIONS
Pin Name
AGND/DGND
A(TIP)
Type
Description
Ground
Output
Ground
Output
Inputs
Analog and Digital ground.
Output of A(TIP) power amplifier.
Battery (power) ground.
BGND
B(RING)
C2–C1
Output of B(RING) power amplifier.
Decoder. TTL compatible. C2 is MSB and C1 is LSB.
Anti-Saturation pin for capacitor to filter reference voltage when operating in anti-
saturation region.
CAS
Capacitor
Relay Driver Control. D3–D1 control the relay drivers RYOUT1, RYOUT2, and RYOUT3.
Logic Low on D1 activates the RYOUT1 relay driver. Logic Low on D2 activates the
RYOUT2 relay driver. Logic Low on D3 activates the RYOUT3 relay driver. TTL
compatible.
D3–D1
Input
DA
DB
Input
Input
Ring-trip negative. Negative input to ring-trip comparator.
Ring-trip positive. Positive input to ring-trip comparator.
Switchhook detector. Logic Low indicates that selected detector is tripped. Logic inputs
C2–C1, E1, and E0 select the detector. Open-collector with a built-in 15 kΩ pull-up
resistor.
DET
Output
HPA
HPB
NC
Capacitor
Capacitor
—
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.
RD
Resistor
Detect 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).
RDC
Resistor
Output
RINGOUT
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 500 times the current into this pin. The networks that program
receive gain, two-wire impedance, and feed resistance all connect to this node.
RSN
Input
RYOUT1
RYOUT2
Output
Output
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND.
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND
(PLCC only).
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND
(PLCC only).
RYOUT3
TMG
Output
—
Thermal Management. External resistor connects between this pin and VBAT to offload
power from SLIC.
VBAT
VBREF
VCC
Battery
—
Battery supply and connection to substrate.
This is an Zarlink reserved pin and must always be connected to the VBAT pin.
+5 V power supply.
Power
Transmit Audio. This output is a 0.50 gain version of the A(TIP) and B(RING) metallic
voltage. VTX also sources the two-wire input impedance programming network.
VTX
Output
5
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
