HM 9270C/D
DTMF RECEIVER
General Description
The HM 9270C/D is a complete DTMF receiver integrating both the bandsplit filter and digital decoder
functions. The filter section uses switched capacitor techniques for high- and low-group filters and dial-tone
rejection. Digital counting techniques are employed in the decoder to detect and decode all 16 DTMF tone-
pairs into a 4-bit code. External component count is minimized by on-chip provision of a differential input
amplifier, clock-oscillator and latched 3-state bus interface.
Features
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Complete receiver in an 18-pin package.
Excellent performance.
CMOS, single 5 volt operation.
Minimum board area.
Central office quality.
Low power consumption.
Power-Down mode (HM9270D only).
Inhibit-mode (HM9270D only).
Pin Configurations
HM9270C
IN+
IN
GS
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
V
DD
St/GT
ESt
StD
Q4
Q3
Q2
Q1
TOE
IN+
IN
GS
HM9270D
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
V
DD
St/GT
ESt
StD
Q4
Q3
Q2
Q1
TOE
V
REF
IC*
IC*
OSC1
OSC2
V
SS
V
REF
INH
PWDN
OSC1
OSC2
V
SS
* Connect to V
SS
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EMC [ ELAN MICROELECTRONICS CORP ]
