ISL5585_04 Datasheet, PDF (22/24 Pages) Intersil Corporation – 3.3V Ringing SLIC Family for Voice Over Broadband (VOB)

ISL5585
+
V_2W
-
C_PS1
C_PS2
C_PS3
D₁ 1N4004
CODEC
R_P1
49.9Ω
600Ω ^RP2
49.9Ω
C_RT
R_RT
R_SH
R_IL
C_DC
VCC VBL VBH
TIP
AUX
U₁
VTX
RING
ISL5585 -IN
RT
SH
ILIM
VFB
CDC
POL
C_RS
VRS
AGND
TL
BGND
0.47uF
R_S ^66.5kΩ
R_A
36.5kΩ
R_IN
30.1kΩ RF
0.47uF R_B
42.2kΩ
-
+
TX IN
Digital
Gain
0dB
+2.4V
45.3kΩ 0.47uF
C_FB
C_POL
PCM to V_2W Gain = +3.33dB, digital gain set to 0dB
V_CC
V_2W to PCM Gain = -9.3 dB, digital gain set to 0dB
0 dBm0, CODEC output voltage = 0.531Vrms
0 dBm0, V_2W = 0.7795Vrms
Digital
Gain
0dB
R_TL
Design Equations
R_S = 133.33(Z_L - 2R_P)
Gain PCM to V_2W = R_S/R_IN = 66.5k/45.3k =1.46
dB Gain =20log (0.7795/ 0.531) = +3.33dB
V_2W to PCM Gain = V_2W (G_2-4)(R_F/R_A) = (0.7795)(0.416)(30.1k/36.5k) = 0.267
dB Gain =20log (0.267/0.7795) = - 9.3dB
PCM
PCM
FIGURE 17. ISL5585 3.3V APPLICATION CIRCUIT
22