HC-5504DLC Datasheet, PDF (5/9 Pages) Intersil Corporation – SLIC Subscriber Line Interface Circuit

Specifications HC-5504DLC
Pin Descriptions (Continued)
28 PIN
24 PIN
PLCC DIP/SOIC SYMBOL
DESCRIPTION
19
16
RC Ring Command - A low active TTL - Compatible logic input. When enabled, the relay driver (RD)
output goes low on the next high level of the ring sync (RS) input, as long as the SLIC is not in the
power denial state (PD = 0) or the subscriber is not already off- hook (SHD = 0).
20
17
C2 Capacitor #2 - An external capacitor to be connected between this terminal and digital ground.
Prevents false ground key indications from occurring during ring trip detection. Typical value is
0.15µF, 10V. This capacitor is not used if ground key function is not required and (Pin 17) may be left
open or connected to digital ground.
21
18
OUT The analog output of the spare operational amplifier. The output voltage swing is typically ±5V.
23
19
-IN The inverting analog input of the spare operational amplifier.
24
20
+IN The non-inverting analog input of the spare operational amplifier.
25
21
RX Receive Input, Four Wire Side - A high impedance analog input which is internally biased. Capacitive
coupling to this input is required. AC signals appearing at this input differentially drive the Tip feed and
Ring feed terminals, which in turn drive tip and ring through 300Ω of feed resistance on each side of
the line.
26
22
C4 Capacitor #4 - An external capacitor to be connected between this terminal and analog ground. This
capacitor prevents false ground key indication and false ring trip detection from occurring when
longitudinal currents are induced onto the subscriber loop from near by power lines and other noise
sources. This capacitor is also required for the proper operation of ring trip detection. Typical value is
0.5µF, to 1.0µF, 20V. This capacitor should be nonpolarized.
27
23
AG Analog Ground - To be connected to zero potential and serves as a reference for the transmit output
(TX) and receive input (RX) terminals.
28
24
TX Transmit Output, Four Wire Side - A low impedance analog output which represents the differential
voltage across Tip and Ring. Transhybrid balancing must be performed (using the SLIC microcircuit’s
spare op amp) beyond this output to completely implement two to four wire conversion. This output is
unbalanced and referenced to analog ground. Since the DC level of this output varies with loop
current, capacitive coupling to the next stage is essential.
1,8,15,22
NC No Internal Connection.
NOTE: All grounds (AG, BG, & DG) must be applied before V_B+ or V_B-. Failure to do so may result in premature failure of the part. If a user
wishes to run separate grounds off a line card, the AG must be applied first.
Functional Diagram
RS
RING SYNC
RC
RING COMMAND
RD
TIP
1/2 RING
TIP
RELAY _150Ω
150Ω
2 WIRE
TF
LOOP
BG
SECONDARY
PROTECTION
V_B-
V_B-
RF
1/2 RING
RELAY
RFS
150Ω
RING
150Ω
RING
RING
VOLTAGE
PD
POWER DENIAL
V_B-
RING
CONTROL
RING
TRIP
LOOP
MONITORING
DIFF
AMP
+
SHD _{SWITCH HOOK}
DETECTION
GKD _{GROUND KEY}
DETECTION
TX TRANSMIT
OUTPUT
BATTERY
FEED
LOOP
CURRENT
LIMITER
+1
LINE
DRIVERS
-1
SLIC MICROCIRCUIT
+
OP
AMP
OUT
+IN
-IN
RX _RECEIVE
INPUT
8-23