1
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
8.8.2000
I. GENERAL DESCRIPTION
This is a new version of Call Waiting service decoder on the telephone. Call Waiting service works by alerting
a customer engaged in a telephone call to a new incoming call. This way 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
signal and generate a valid signal 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 Signal Detector
• Good talkdown and talkoff performance
• Sensitivity compensated by adjusting input OP gain
• Package series --- 14-pin DIP or 16-pin SOP (150 mil)
AG8889AP for 14-pin DIP
AG8889N for 16-pin SOP (150 mil)
III. APPLICATION
• Feature phones
• Cordless phones
• Adjunct unit (stand alone)
IV. PIN CONFIGURATION
VSS
VDD
DO
OSCI
OSCO
14
13
12
11
9
1
2
3
4
5
6
78
OPO
RING
VREF
10
NC
PWD
NC
NC
NC
TIP
AG8889AP
VSS
VDD
DO
OSCI
OSCO
16
15
14
13
11
1
2
3
4
5
6
710
OPO
RING
VREF
12
NC
PWD
NC NC
89
NC
NC
NC
TIP
AG8889N
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
2
8.8.2000
V. FUNCTIONAL BLOCK DIAGRAM
VI. PIN DESCRIPTIONS
Pin I/O Description
TIP I Tip in should be connected with twisted pair
RING I Ring in should be connected with twisted pair
OPO O Output of OP Amp
VREF Reference voltage Vref = 1/2 Vdd
PWD I This pin is normal low enabling chip on normal operation and ready to detect CAS
tone signals.
This active high input sets the chip into power down mode and disable oscillator to
save power.
OSCI I 3.58MHz oscillator in
OSCO O 3.58MHz oscillator out
DO O DO : used as output, this pin determines whether DO signal is valid or not. High is
valid. Normal low.
VDD Power
GND 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. This way the
customer can still receive important calls while engaged in a current call. The CALL WAITING DECODER can detect
CAS(Call-Waiting Alerting Signal 2130Hz plus 2750Hz) and generate a valid signal on the data pin.
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 three blocks, including dif ferential amplifier , tone filter detection block
In a typical application, this IC receives Tip and Ring signals from twisted pairs. The signals as inputs of dif ferential
amplifier , and the differential amplifier sends input signal to a band pass tone filter . Once the signal is filtered, the
digital detection block decodes the information. The output data made available at DO pin.
This IC is used for detecting CAS signals. Once the signal is detected, the detection indication is shown on the data
output DO pin. The DO pin is normal low. When this IC detects 2130Hz and 2750Hz frequency at the same time, then
DO pin goes to high.
TIP
Filter
Vdd/2 Voltage
Reference Clock
Generator
DO
OPO
Tone Detection Block
VREF
PWDOSCI OSCO
RING
3
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
8.8.2000
DC CHARACTERISTIC
VDD=5V, Vss=0V, Ta=25°C, fOSC=3.58MHz
Sym. Description Condition Min. Typ. Max. Unit
VDD operating supply voltage 3.6 6 V
IDD operating supply current 3.3 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 TIP and RING pins ,Vdd=+5V, Input G=1 -38 dBm
Input frequency tolerance for 2130Hz ±1.2 %
Input frequency tolerance for 2750Hz ±1.2 %
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
4
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
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
OSCI
OSC on
OSC off Tosc
(OSCO)
Power power off power on
on/off
PWD
Tosc
OSC off
Note: detected alert tone length shown above is assumed that no speech signals input.
test under alert tone signal = -22dBm (600Ω)
5
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
8.8.2000
APPLICATION CIRCUIT 1
When PWD pin (pin 6) is controlled by MCU or external hook detect circuit, the users can use the following
application. (pin6 is connected to control pin of MCU or hook detect output)
TIP
VREF
GND
8-bit
MCU
TIP
RING
OSCI
OSCO
0.01u
0.01u
430k
250V
250V
0.1u
VDD 14
3
4
13
9
8
7
1
OPO
470k
5V
430k 51k
39k
62k
39k
5V
47p
2RING
DO
PWD 6
3.58MHz
33p
Y1
C2
Y1
C1
C2
KBR-3.58MSB202
KYOCERA
33p
Note :
KBR-3.58MSB202 tolerrance :
-0.10% ~+0.15%
33p
C1
33p
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
6
8.8.2000
APPLICATION CIRCUIT 2
In some application, the call waiting decoder is always powered on , the PWD pin (pin 6) can not be directly
connected to the ground, the users have to use the following application. (pin6 is connected with a capacitor to
VDD and connected with a resistor to the ground).
TIP
VREF
GN
D
8-bit
MCU
TIP
RING
OSCI
OSCO
0.01u
0.01u
430k
250V
250V
0.1u
VD
D14
3
4
13
9
8
7
1
OPO
470k
5V
430k 51k
39k
62k
39k
5V
47p
2RING
DO
PWD 6
3.58MHz
33p
Y1
C2
Y1
C1
C2
KBR-3.58MSB202
KYOCERA
33p
Note :
KBR-3.58MSB202 tolerrance :
-0.10% ~+0.15%
33p
C1
33p
20k
470p
5V
7
* This specification are subject to be changed without notice.
AG8889
CALL WAITING DECODER
8.8.2000
APPLICATION NOTE
1. VDD, GND
To reduce noise effects, separate the analog and digital systems close to the device. For both the digital and
analog VDD pins, use a ceramic capacitor of about 0.1uF set as close as possible to the pin to bypass to the
respective GND's.
2. PWD pin
By connecting PWD pin to GND, normal mode is obtained. In the normal mode, the oscillator is activated then
ready to decode CAS signal and the chip consumes operating current. By connecting PWD pin to VDD, the
chip is on power down mode and the chip consumes just stand-by current.
3. OPO pin
This pin is the gain adjustment of internal OP Amp.
4. XIN, XOUT pins
If the resonator is used, two capacitors about 33pF and 1M( resistor have to be connected for frequency
accuracy.
