1
* This specification are subject to be changed without notice.
AG8888
CALL WAITING DECODER
8.8.2000
I.
GENERAL DESCRIPTION
This is a Call Waiting decoder used on the telephone. Call Waiting service works by alerting a customer engaged
in a telephone call to a new incoming call. Thus, the customer can still receive important calls while engaged in
a current call. The Call Waiting decoder can detect dual-tone (2130Hz and 2750Hz) alert tone and generate a
valid timing on the data pins for micro controller.
II.
FEATURES
Compatible with Bellcore special report SR-TSV-002476
3.6V ~ 6.0V supply voltage
Call-Waiting (2130Hz plus 2750Hz) alert tone detector
Sensitivity compensated by adjusting OP Amp
Internal buffer
Detection block for alert tone detected and digital algorithm detection
Package series --- 14-pin DIP or 16-pin SOP (150 mil)
AG8888AP for 14-pin DIP
AG8888N for 16-pin SOP (150 mil)
III.
APPLICATION
Feature phones, cordless phones and stand-alone product
IV. PIN CONFIGURATION
DVSS
OPO
AVDD
OSCI
OSCO
14
13
12
11
9
1
2
3
4
5
6
7
8
F1
BO
AVSS
10
OE
NC
DO
NC
DVDD
TI/RI
AG8888AP
DVSS
OPO
AVDD
OSCI
OSCO
16
15
14
13
11
1
2
3
4
5
6
7
10
F1
BO
AVSS
12
OE
NC
NC
NC
8
9
DO
NC
DVDD
TI/RI
AG8888N
* This specification are subject to be changed without notice.
AG8888
CALL WAITING DECODER
2
8.8.2000
V.
FUNCTIONAL BLOCK DIAGRAM
VI. PIN DESCRIPTIONS
Pin
I/O
Description
TI/RI
I
Tip in or Ring in should be connected with twisted pair
OE
I
Output enable for alert tone detected. High is enable. Low is for factory test.
OSCI
I
480KHz crystal in
OSCO
O
480KHz crystal out
DO
O
Alert tone detected output. Normal low.
Under OE pin set to high, when call waiting alert tone is detected, this pin goes to high.
OPO
O
Output of OP Amp
BO
O
Internal buffer output
FI
I
Band pass filer input
AVDD
Analog power.
DVDD
Digital power.
AVSS
Analog Ground.
DVSS
Digital Ground.
NC
Non connected
VII. FUNCTIONAL DESCRIPTIONS
Call Waiting service works by alerting a customer engaged in a telephone call to a new incoming call. Thus, the
customer can still receive important calls while engaged in a current call. The call waiting decoder can detect alert
tone (Call-Waiting Alerting Signal 2130Hz plus 2750Hz) and generate a valid timing on the data pins.
The call waiting decoder is designed to support the Caller Number Deliver feature, which is offered by regional
Bell Operating Companies. The call waiting decoder has four blocks, including OP Amp, band pass filter, and
detection block.
In a typical application, this IC receives Tip/Ring signals from twisted pairs. The signals as inputs of single-ended
pre-amplifier (OP Amp and Buffer Amp), and the amplifier sends input signal to a band pass filter. Once the
TI/RI
Filter
Vdd/2
Voltage
Reference
Clock
Generator
DO
OPO
Tone
Detection Block
OE
OSCI
OSCO
Buffer
BO
FI
3
* This specification are subject to be changed without notice.
AG8888
CALL WAITING DECODER
8.8.2000
signal is filtered, the detection block decodes the information and sends a valid timing to DO pin. The output data
made available at DO pin. There is a OE pin to control DO pin's output enable.
There is an external clamp circuit between internal buffer amplifier and filter. In order to get great alert tone
detection and avoid false triggering while speech signal is coming, the external clamp circuit can restrict speech
signal to (0.6Vp-p from TIP/RING.
The input signal is call waiting alert tone signals. The DO pin is normal low. When OE pin set to high and this IC
detects 2130Hz and 2750Hz frequency, then DO pin goes to high. Because OE pin set to low be for factory test,
you should notice that the users don't set it to low.
For this decoder, we put some external elements for performance concern.
* This specification are subject to be changed without notice.
AG8888
CALL WAITING DECODER
4
8.8.2000
DC ELECTRICAL CHARACTERISTIC
VDD=5V, Vss=0V, Ta=25
C, fOSC=480KHz
Sym.
Description
Condition
Min.
Typ.
Max.
Unit
VDD
operating supply voltage
3.6
6
V
IDD
operating supply current
3.3
1.5
mA
VIL
low level input voltage
1.5
V
VIH
high level input voltage
3.5
V
VOL
low level output voltage
load=1mA
0.4
V
VOH
high level output voltage
load=1mA
4.6
V
Note: 1.both tones in the composite signal have equal amplitude.
2.tone pair is deviated by 0.5%.
3.addes a 0.1uf capacitor between Power and Ground.
AC ELECTRICAL CHARACTERISTIC
(VDD=+5V,Ta=+25
C)
CHARACTERISTIC
Min.
Typ.
Max.
Unit
Input sensitivity ,VDD=+5V, Input G=1
-36
dBm
Input frequency tolerance for 2130Hz
1.2
%
Input frequency tolerance for 2750Hz
1.2
%
5
* This specification are subject to be changed without notice.
AG8888
CALL WAITING DECODER
8.8.2000
WAVE FORM TIMING
DO timing:
OSC timing:
line event
Tvd
CAS
Tinvd
normal on hook
Tfvd
Tfinvd
Tdvd
Tdinvd
Tvd=Tfvd+Tdvd
Tinvd=Tfinvd+Tdinvd
alert
tone
(~80ms)
off hook
engaged call
OSCI
OSC on
OSC off
Tosc
(OSCO)
Power
power off
power on
on/off
Sym.
Description
Min.
Typ.
Max.
Unit
Tfvd
filter output signal valid delay
6
ms
Tfinvd
filter output signal invalid delay
6
ms
Tdvd
digital delay of valid signal
36
ms
Tdinvd
digital delay of invalid signal
20
ms
Tvd
total delay of valid signal
42
ms
Tinvd
total delay of invalid signal
26
ms
alert
input alert tone length
80
ms
tone
(2130 ,2750 Hz @ -20dBm )
Tosc
Oscillator enable delay time
10
ms
Note: detected alert tone length shown above is assumed that no speech signals input.
This test is under alert tone signal = -22dBm (600
)
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