Le79489
PIN DESCRIPTIONS
Pin Names
AGND/DGND
A(TIP)
BGND
B(RING)
BSWEN
Type
Gnd
Output
Gnd
Output
—
Analog and Digital ground.
Output of A(TIP) power amplifier.
Battery (power) ground.
Output of B(RING) power amplifier.
Description
Data Sheet
Battery Switch Control. Internally connected to automatic battery switch circuitry. BSWEN can be
overridden by external logic. BSWEN Low connects VBAT1 to VBAT2. BSWEN High disconnects
VBAT1 from VBAT2.
Buffered Output. Internally connected to battery switch circuitry. The output is open-collector with a
built-in pull-up resistor. BSWOUT Low indicates VBAT1 is connected to VBAT2. BSWOUT High
indicates VBAT1 is disconnected from VBAT2. This output is valid only in the Active states.
Input for setting automatic battery switch threshold. Normally tied to Battery 2. Tie to ground for
manual switching.
Decoder. TTL compatible. C3 is MSB and C1 is LSB.
Test Relay Input – Active Low. 1 = Off. 0 = On.
Anti-sat pin for capacitor to filter reference voltage when operating in anti-sat region.
Ring-trip negative. Negative input to ring-trip comparator.
Ring-trip positive. Positive input to ring-trip comparator.
Switchhook detector. When enabled, a logic Low indicates the selected detector is tripped. The detector
is selected by the logic inputs (C3–C1). The output is open-collector with a built-in 15 kΩ pull-up
resistor.
Ground-Key Detect Select. E1 = 1 selects the hook switch detector. E1 = 0 selects the ground-key
detector. In the Tip Open state, ground key is selected independent of E1.
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. This pin not internally connected.
Overhead Control. Logic High enables minimized nonmetering overhead. Logic Low enables 2.2 V
metering DC overhead. TTL-compatible.
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). Connection point for the DC feed current
programming network. The other end of the network connects to RSN. V
RDC
is negative for normal
polarity and positive for reverse polarity.
Resistive feed adjust. Adjust the DC feed resistance gain coefficient, GDC, with external resistor
connected to ground.
Ring Relay Driver. Open-collector driver with emitter internally connected to BGND.
Receive Summing Node. The metallic current (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 current all connect to this node.
Reserved. These pins are reserved for
Zarlink
use. Make no connection to these pins.
Test Relay Driver. Open collector driver with emitter internally connected to AGND.
Thermal Management. External resistor connects this pin to VBAT2 to offload power dissipation from
SLIC. Functions during normal polarity, Active state.
Most negative battery supply and substrate connection.
Battery supply for output power amplifiers. Switched to VBAT1 by BSWEN.
+5 V power supply.
Transmit Audio. This output is a 0.5066 unity gain version of the A(TIP) and B(RING) metallic voltage.
VTX also sources the two-wire input impedance programming network.
This must be electrically tied to VBAT1.
BSWOUT
Output
BSWTH
C3–C1
C4
CAS
DA
DB
DET
Input
Input
Input
Capacitor
Input
Input
Output
E1
HPA
HPB
NC
OVH
RD
RDC
Input
Capacitor
Capacitor
—
Input
Resistor
Resistor
RFA
RINGOUT
RSN
—
Output
Input
RSVD
TESTOUT
TMG
VBAT1
VBAT2
VCC
VTX
Exposed Pad
—
Output
—
Battery
Battery
Power
Output
Battery
4
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
