HC-5502B1 Datasheet, PDF (6/12 Pages) Intersil Corporation – SLIC Subscriber Line Interface Circuit

HC-5502B1
Pin Descriptions (Continued)
28 PIN
PLCC
24 PIN
DIP/SOIC SYMBOL
DESCRIPTION
26
22
C₄
Capacitor #4 - An external capacitor to be connected between this terminal and analog ground. This ca-
pacitor prevents false ground key indication and false ring trip detection from occurring when longitudinal
currents are induced onto the subscriber loop from nearby power lines and other noise sources. This ca-
pacitor 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 volt-
age 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 unbal-
anced and referenced to analog ground. Since the DC level of this output varies with loop current, capac-
itive coupling to the next stage is essential.
1, 8, 5, 22
NC
No Internal Connection.
NOTE:
5. All grounds (AG, BG, and 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
RING
RS
VOLTAGE
RING SYNC
RC
RING COMMAND
RD
TIP
RING
RELAY
TIP
150Ω
150Ω
2-WIRE
LOOP
V_B-
RING
SECONDARY
PROTECTION
TF
V_B-
BG
RF
150Ω
RING
150Ω
PD
POWER DENIAL
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
4-6