HC5517_00 Datasheet, PDF (16/19 Pages) Intersil Corporation – 3 REN Ringing SLIC For ISDN Modem/TA and WLL

HC5517
signals are nearly static, care should be taken to minimize
coupling of the sharp digital edges to the analog signals.
The part has two ground pins, one is labeled AGND and the
other BGND. Both pins should be connected together as
close as possible to the SLIC. If a ground plane is available,
then both AGND and BGND should be connected directly to
the ground plane.
Application Pin Descriptions
A ground plane that provides a low impedance return path
for the supply currents should be used. A ground plane
provides isolation between analog and digital signals. If the
layout density does not accommodate a ground plane, a
single point grounding scheme should be used.
PLCC
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SYMBOL
DESCRIPTION
AGND
Analog Ground - To be connected to zero potential. Serves as a reference for the transmit output and receive input
terminals.
V_CC
V_REF
Positive Voltage Source - Most Positive Supply.
Ring amplifier reference override. An external voltage connected to this pin will override the internal V_BAT/2
reference.
F1
Power Denial -A low active TTL compatible logic control input. When enabled, the output of the ring amplifier will ramp
close to the output voltage of the tip amplifier.
F0
TTL compatible logic control input that must be tied high for proper SLIC operation.
RS
TTL compatible logic control input that must be tied high for proper SLIC operation.
SHD
Switch Hook Detection - An active low TTL compatible logic output. Indicates an offhook condition.
RTD
Ring Trip Detection - An active low TTL compatible logic output. Indicates an off-hook condition when the phone is
ringing.
TST
A TTL logic input. A low on this pin will keep the SLIC in a power down mode. The TST pin in conjunction with the ALM pin
can provide thermal shutdown protection for the SLIC. Thermal shutdown is implemented by a system controller that
monitors the ALM pin. When the ALM pin is active (low) the system controller issues a command to the TST pin (low) to
power down the SLIC. The timing of the thermal recovery is controlled by the system controller.
ALM
A TTL compatible active low output which responds to the thermal detector circuit when a safe operating die
temperature has been exceeded.
I_LMT
OUT1
Loop Current Limit - Voltage on this pin sets the short loop current limiting conditions using a resistive voltage divider.
The analog output of the spare operational amplifier.
-IN1
The inverting analog input of the spare operational amplifier. Note that the non-inverting input of the amplifier is
internally connected to AGND.
TIP
SENSE
An analog input connected to the TIP (more positive) side of the subscriber loop through a feed resistor and ring relay
contact. Functions with the RING terminal to receive voice signals from the telephone and for loop monitoring
purpose.
RING SENSE 1 An analog input connected to the RING (more negative) side of the subscriber loop through a feed resistor. Functions
with the TIP terminal to receive voice signals from the telephone and for loop monitoring purposes.
RING SENSE 2 This is an internal sense mode that must be tied to RING SENSE 1 for proper SLIC operation.
V_RX
Receive Input, 4-Wire Side - A high impedance analog input. AC signals appearing at this input drive the Tip Feed
and Ring Feed amplifiers deferentially.
NU
Not used in this application.This pin should be left floating.
V_TX
Transmit Output, 4-Wire Side - A low impedance analog output which represents the differential voltage across TIP
and RING. Since the DC level of this output varies with loop current, capacitive coupling to the next stage is
necessary.
RDI
TTL compatible input to drive the uncommitted relay driver.
RDO
This is the output of the uncommitted relay driver.
BGND
Battery Ground - To be connected to zero potential. All loop current and some quiescent current flows into this
terminal.
NU
Not used in this application. This pin should be either grounded or left floating.
V_RING
TF
Ring signal input (0V to 3V_PEAK at 20Hz).
This is the output of the tip amplifier.
RF
This is the output of the ring amplifier.
V_BAT
The negative battery source.
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