Le7920
PIN DESCRIPTIONS
Pin Name
AGND/DGND
A(TIP)
BGND
B(RING)
C2–C1
CAS
Type
Ground
Output
Ground
Output
Inputs
Capacitor
Analog and Digital ground.
Output of A(TIP) power amplifier.
Battery (power) ground.
Output of B(RING) power amplifier.
Decoder. TTL compatible. C2 is MSB and C1 is LSB.
Description
Data Sheet
Anti-Saturation pin for capacitor to filter reference voltage when operating in anti-
saturation region.
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.
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.
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.
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).
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.
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).
Thermal Management. External resistor connects between this pin and VBAT to offload
power from SLIC.
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.
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.
D3–D1
Input
DA
DB
DET
HPA
HPB
NC
RD
RDC
RINGOUT
RSN
RYOUT1
RYOUT2
RYOUT3
TMG
VBAT
VBREF
VCC
VTX
Input
Input
Output
Capacitor
Capacitor
—
Resistor
Resistor
Output
Input
Output
Output
Output
—
Battery
—
Power
Output
5
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
