CD22202 Datasheet, PDF (3/6 Pages) Intersil Corporation – 5V Low Power DTMF Receiver

Functional Block Diagram
CD22202, CD22203
ANALOG
IN
9
ATB ¹³
XEN ⁸
12
XIN
1MΩ
XOUT
11
PREPROCESSOR
60Hz
REJECT
PRE EMP
÷8
BAND
SPLIT
FILTERS
BS1
ZERO
CROSSING
DETECTORS
BANDPASS
FILTERS
697
770
852
941
BS2
1209
1336
1477
1633
CLOCK
GENERATOR
CHIP CLOCKS
AMPLITUDE
DETECTORS
TIMING
CIRCUITRY
CD22202
CD22203
EARLY
DETECT
OUTPUT
6
CLRDV
15
DV
STROBE
DATA STROBE
CLR
DV
F.F
DV
14
H/B28
2
1 D1
POWER REGULATOR
5
V_DD
10
7
V_SS
V_SS
VOLTAGE
REF
OUTPUT
DECODER
OUTPUT
REGISTER
DATA CLEAR
IN1633 ₄
18 D2
17 D4
16 _D8
3 EN
NOTE: Pin 6: Early detect output on CD22203 only.
System Functions
Analog In
The Analog In pin accepts the analog input. It is internally
biased so that the input signal may be either AC or DC cou-
pled, as long as it does not exceed the positive supply volt-
age. Proper input coupling is illustrated below.
The CD22202 and CD22203 are designed to accept sinuso-
idal input waveforms, but will operate satisfactorily with any
input that has the correct fundamental frequency with har-
monics that are at least 20dB below the fundamental.
AUDIO
INPUT
(+4dBm
MAXIMUM)
1500pF
0.01µF
33kΩ
CD22202, CD22203
V_DD
270kΩ
9
ANALOG
IN
(ON CHIP)
10pF
>100kΩ
V_SS
OPTIONAL
HIGH FREQUENCY
NOISE FILTER
(f_C = 3.9kHz)
Crystal Oscillator
The CD22202 and CD22203 contain an on-board inverter
with sufficient gain to provide oscillation when connected to
a low cost television “color-burst” (3.579545MHz) crystal.
The crystal oscillator is enabled by tying XEN high. The crys-
tal is connected between XIN and XOUT. A 1MΩ resistor is
also connected between these pins in this mode. ATB is a
clock frequency output. Other CD22202 and CD22203
devices may use the same frequency reference by tying their
ATB pins to the ATB output of a crystal connected device.
XIN and XEN of the auxiliary devices must then be tied high
and low, respectively. Up to ten devices may be run from a
single crystal connected CD22202 and CD22203 as shown
in Figure 2.
FIGURE 1. ANALOG IN
4-247