w91031 Winbond Electronics Corp America, w91031 Datasheet - Page 7

• Manufacturer Part Number: w91031
• Description: Calling Line Identifier
• Manufacturer: Winbond Electronics Corp America

The RC time constant of the RNGRC pin is used to delay the output pulse of the RNGON pin for a
low going edge on RNGDI. This edge goes from above the V
going threshold voltage V
ring signal, to ensure a minimum RNGON low interval and to filter the ring signal to get an envelope
output.
The diode bridge shown in Figure 7-1 works for both single ended ring signal and balanced ringing.
R1 and R2 are used to set the maximum loading and must be of equal value to achieve balanced
loading at both the tip and ring line. R1, R3 and R4 form a resistor divider to supply a reduced voltage
to the RNGDI input. The attenuation value is determined by the detection of minimal ring voltage and
maximum noise tolerance between tip/ring and ground.
Allowance minimal ring voltage (peak to peak) is:
Vpp
Tolerance to noise between Tip and Ring and Vss is:
Vpeak
Time constant is:
V
T = R5 C3 ln [V
T+(min)
Ring/B
Tip/A
(max ring)
(max noise)
<= V
C1 = 0.1uF
= 2 (V
T+
T-
DD
C1 = 0.1uF
<= V
= V
. The RC time constant must be greater than the maximum period of the
/ (V
T+(max)
T+(min)
T+(max)
Figure 7-1. Application Circuit of the Ring Detecter
DD
R1 = 470K
R2 = 470K
- V
(R1 + R3 + R4) / R4 + 0.7)
(R1 + R3 + R4) / R4 + 0.7
T+
)]
R3 = 200K
- 7 -
C3 = 0.22uF
R5=150K
R4 = 300K
V
DD
V
DD
R5 from 10K ohm to 500K ohm.
C3 from 47 nF to 0.68 uF.
RNGON
RNGRC
RNGDI
T+
Publication Release Date: August 2000
Preliminary W91031
voltage to the Schmitt trigger low
W91031
Revision A1