HC55171_03 Datasheet, PDF (2/20 Pages) Intersil Corporation – 5 REN Ringing SLIC for ISDN Modem/TA and WLL

HC55171
Pin Descriptions
PLCC
SYMBOL
DESCRIPTION
1
AGND
Analog Ground - Serves as a reference for the transmit output and receive input terminals.
2
V_CC
Positive Voltage Source - Most Positive Supply.
3
V_REF
An external voltage connected to this pin will override the internal V_BAT/2 reference.
4
F1
Power Denial - An active low TTL compatible logic control input. When enabled, the output of the ring amplifier will
ramp close to the output voltage of the tip amplifier.
5
F0
TTL compatible logic control input that must be tied high for proper SLIC operation.
6
RS
TTL compatible logic control input that must be tied high for proper SLIC operation.
7
SHD
Switch Hook Detection - An active low TTL compatible logic output. Indicates an off-hook condition.
8
RTD
Ring Trip Detection - An active low TTL compatible logic output. Indicates an off-hook condition when the phone is
ringing.
9
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.
10
ALM
A TTL compatible active low output which responds to the thermal detector circuit when a safe operating die
temperature has been exceeded.
11
I_LMT
Loop Current Limit - Voltage on this pin sets the short loop current limiting conditions.
12
OUT1
The analog output of the spare operational amplifier.
13
-IN1
The inverting analog input of the spare operational amplifier. The non-inverting input is internally connected to AGND.
14
TIP SENSE An analog input connected to the TIP (more positive) side of the subscriber loop through a feed resistor. Functions
with the RING terminal to receive voice signals and for loop monitoring purpose.
15 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 and for loop monitoring purposes.
16 RING SENSE 2 This is an internal sense mode that must be tied to RING SENSE 1 for proper SLIC operation.
17
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.
18
NU
Not used in this application. This pin should be left floating.
19
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.
20
RDI
TTL compatible input to drive the uncommitted relay driver.
21
RDO
This is the output of the uncommitted relay driver.
22
BGND
Battery Ground - All loop current and some quiescent current flows into this terminal.
23
NU
Not used in this application. This pin should be either grounded or left floating.
24
V_RING
Ring signal input.
25
TF
This is the output of the tip amplifier.
26
RF
This is the output of the ring amplifier.
27
V_BAT
The negative battery source.
28
RTI
Ring Trip Input - This pin is connected to the external negative peak detector output for ring trip detection.
2