HC55171_03 Datasheet, PDF (18/20 Pages) Intersil Corporation – 5 REN Ringing SLIC for ISDN Modem/TA and WLL

HC55171
The 4-wire transmit and receive signal paths should not
cross. The receive path is any trace associated with the V_RX
input and the transmit path is any trace associated with V_TX
output. The physical distance between the two signal paths
should be maximized to reduce crosstalk.
The mode control signals and detector outputs should be
routed away from the analog circuitry. Though the digital
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.
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.
V_RX
VOUT1
HC55171
R_A
R_F
R_B
CODEC
RX OUT
-
+
TX IN
+2.5V
+
-
FIGURE 20. SINGLE SUPPLY CODEC INTERFACE
Trapezoidal Ringing Application Circuit
U1
TIP
RING
V_CC
V_BAT
F1
F0
TST
R_S1
R_S2
C_PS1
C_PS2
VCC
HC55171
14 TIP SENSE
25 TF
V_RX 17
ILIMT 11
R_IL2
26 RF
R_IL1
16 RING SENSE 2 V_TX 19
C_AC
15 RING SENSE 1
R_RF
-IN1 13
2 V_CC
1 AGND
OUT1 12
RTI 28
R_ZO
R_RT2
22 BGND
R_RT3
C_RX
R_RT1
C_RT
D_RT
27 V_BAT
4 F1
5 F0
6 RS
9 TST
20 RDI
V_RING 24
V_REF 3
C_IL
D_TRAP
SHD 7
RTD 8
ALM 10
R_TRAP
C_TRAP
V-REC
V-XMIT
V_RING
SHD
RTD
ALM
FIGURE 21. TRAPEZOIDAL RINGING APPLICATION CIRCUIT
18