w91030b Winbond Electronics Corp America, w91030b Datasheet - Page 7

• Manufacturer Part Number: w91030b
• Description: Calling Line Identifier
• Manufacturer: Winbond Electronics Corp America

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.
Input Pre-processor
The input signal is processed by an Input Pre-Processor, which is added to the offset voltage to adjust
the input amplitude and to filter out unwanted frequencies. The gain control op-amp is used to bias
the input voltage with the VREF signal voltage. The voltage of VREF pin is V
had better connected a 0.1uF capacitor to V
feedback resistor between this pin and the INN pin. Figure 7-2 shows the necessary connections with
the tip/ring line inputs. In a single-ended configuration, the gain control op-amp is connected as
shown in Figure 7-3.
Dual Tone Alert Signal Detection
The dual tone alert signal is separated into high and low tones and detected by a high/low tone
detector. The dual tone alert signal detection circuit is always enabled when the W91030B/BS is not
in sleep state. The ALGR is the output of the dual tone detector and when high indicates that the high
tone and low tone alert signals have been detected. The guard time improves detection performance
by rejecting detected signals with insufficient duration and by masking momentary detection dropout.
Figure 7-4 shows the relationship between the ALGR, ALGRC and ALGO pins and Figure 7-5 shows
the guard time waveform of the same pins. The total recognition time is t
the tone present detect time and t
the RC time constant with the capacitor discharging from V
from V
ALGO returns high. The total absent time is t
and t
Differential Input Amplifier
C1 = C2
R1 = R2
R3 = (R4 R5) / (R4 +R5)
Ring
Tip
GA
Figure 7-2 Differential Input Gain Control Circuit
SS
is the tone absent guard time. The tone absent guard time is the RC time constant with the
C2
C1
to V
R1
R2
DD
through a resistor). The capacitor will discharge rapidly via a discharge switch after
Voltage Gain
Av = R5 / R1
Input Impedance
Zin = 2
R3
R4
R1
R5
0.1 uF
2
+ (1 / wC)
VREF
GCFB
INN
INP
GP
2
W91030B
is the tone present guard time. The tone present guard time is
+
-
SS
ABS
. It is also used to select the input gain by connecting a
- 7 -
= t
DA
Voltage Gain
Input
A
V
+ t
= R2 / R1
Figure 7-3 Single-ended Input Gain Control Circuit
GA
C
, where t
SS
Preliminary W91030B
R1
to V
Publication Release Date: March 2000
DD
DA
is the tone absent detect time
( the ALGRC pin discharges
REC
R2
0.1 uF
= t
VREF
DD
INN
GCFB
INP
DP
/2 typically, this pin
+ t
GP
W91030B
+
-
, where t
Revision A1
DP
is