Le79555
PIN DESCRIPTIONS
Pin Name
AGND/
DGND
A(TIP)
BGND
B(RING)
C3–C1
CAS
CHCLK
CHS
D2–D1
DA
DB
DET
HPA
HPB
L
N/C
QBAT
RD
RDC
RINGOUT
RSN
RYOUT1
RYOUT2
VBAT
RSVD
VCC
VDC
VREG
VTX
Exposed
Pad (QFN
package)
Type
Ground
Output
Ground
Output
Input
Capacitor
Input
Input
Input
Input
Input
Output
Capacitor
Capacitor
Output
—
Battery
Resistor
Resistor
Output
Input
Output
Output
Battery
—
Power
Supply
Output
Input
Output
Battery
Analog and digital ground.
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.
Description
Data Sheet
Anti-Saturation pin for capacitor to filter reference voltage when operating in anti-saturation region.
(Chopper Clock) Input to switching regulator. Freq = 200 to 600 kHz.
(Chopper Stabilization) Connection for external stabilization components.
Relay Driver Control. D1 and D2 control the relay drivers RYOUT1 and RYOUT2. Logic Low on D1
activates the RYOUT1 relay driver. Logic Low on D2 activates the RYOUT2 relay driver.
Negative input to ring-trip comparator.
Positive input to ring-trip comparator.
Hook-switch detector. A logic Low indicates that selected condition is detected. The detect condition is
selected by the logic inputs (C3–C1). The output is open-collector with a built-in 15 kΩ pull-up resistor.
A (TIP) side of high-pass filter capacitor.
B (RING) side of high-pass filter capacitor.
(Switching Regulator Power Transistor) Connection point for filter inductor and anode of catch diode.
This pin will have up to 60 V of pulse waveform on it, and it must be isolated from sensitive circuits.
Care must be taken to keep the diode connections short because of the high currents and di/dt.
No Connect. This pin is not internally connected.
(Quiet Battery) Filtered battery supply for the signal-processing circuits.
Detector threshold set and filter pin.
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. In the Active, Reverse Polarity, and Tip Open states, 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 which 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.
Most negative battery.
This is a reserved pin and must always be left open.
+5 V power supply.
Output that is proportional to the line voltage: VDC
=
KDC
•
VAB . KDC is the VDC scale factor.
(Regulated Voltage) Provides internal negative power supply and connection point for inductor, filter
capacitor, and chopper stabilization.
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.
This must be connected to the most negative battery on the SLIC device pin side of D
VBH
shown on
the test and application circuits.
6
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
