HM9270C Ver la hoja de datos (PDF) - ELAN Microelectronics
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HM9270C Datasheet PDF : 10 Pages
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HM 9270C/D
DTMF RECEIVER
Input Configuration
The input arrangement of the HM9270C/D provides a differential-input operational amplifier as well as a
bias source (VREF ) which is used to bias the inputs at mid-rail.
Provision is made for connection of a feedback resistor to the op-amp output (GS) for adjustment of gain.
In a single-ended configuration, the input pins are connected as shown in Fig. 2 with the op-amp connected
for
unity
gain
and
V
REF
biasing
the
input
at
1/2VDD.
Fig. 9 shows the differential configuration, which permits the adjustment of gain with the feedback resistor
R5.
C1 R1
HM9270C/D
+
-
C2 R4
R5 GS
R3
R2
VREF
FIGURE 9. DIFFERENTIAL INPUT CONFIGURATION
Power - down and inhibit mode
A logic high applied to pin 6 (PWDN) will power the device to minimize the power consumption in a standby
mode. It stops the oscillator and the functions of the filters.
Inhibit mode is enabled by a logic high input to the pin 5 (INH). It inhibits the detection of 1633 Hz. The output
code will remain the same as the previous detected code (see table 1).
fLow Fhigh Key TOE Q4
697 1209 1
HL
697 1336 2
HL
697 1477 3
HL
770 1209 4
HL
770 1336 5
HL
770 1477 6
HL
852 1209 7
HL
852 1336 8
HH
852 1477 9
HH
941 1336 0
HH
941 1209 *
HH
941 1477 #
HH
697 1633 A H H
770 1633 B H H
852 1633 C H H
941 1633 D H L
--
ANY L Z
INH =V
SS
Q3 Q2 Q1
LLH
L HL
L HH
HL L
HL H
HHL
HHH
LLL
LLH
L HL
L HH
HL L
HL H
HHL
HHH
LLL
ZZZ
fLow Fhigh Key TOE
697 1209 1
H
697 1336 2
H
697 1477 3
H
770 1209 4
H
770 1336 5
H
770 1477 6
H
852 1209 7
H
852 1336 8
H
852 1477 9
H
941 1336 0
H
941 1209 *
H
941 1477 #
H
697 1633 A H
770 1633 B H
852 1633 C H
941 1633 D H
--
ANY L
Q4 Q3 Q2 Q1
LLLH
L L HL
L L HH
L HL L
L HL H
L HHL
L HHH
HL L L
HL L H
HL HL
HL HH
HHL L
PREVIOUS DATA
ZZZZ
Table 1: Truth table
(Z: high impedance)
INH=V
DD
-9-
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