HT9172 Datasheet, PDF (1/13 Pages) Holtek Semiconductor Inc – DTMF Receiver

HT9172
DTMF Receiver
Technical Document
· Tools Information
· FAQs
· Application Note
Features
· Operating voltage: 2.5V~5.5V
· Minimal external component requirements
· No external filter required
· Low standby current in power down mode)
· Excellent performance
· Tristate data output for MCU interface
· 3.58MHz crystal or ceramic resonator oscillator
· 1633Hz can be inhibited by the INH pin
· 18-pin DIP/SOP packaging
General Description
The HT9172 is a Dual Tone Multi Frequency (DTMF) re-
ceiver device which includes an integrated digital de-
coder and band split filter functions as well as
power-down and inhibit mode operations. The device
uses digital counting techniques to detect and decode
the full range of 16 DTMF tone pairs into a 4-bit code
output. Highly accurate switched capacitor filters are uti-
lised to divide the DTMF dual tone frequencies into low
and high group signals. An integrated dial tone rejection
circuit is provided to eliminate the need for pre-filtering.
Block Diagram
X2
3 .5 8 M H z
X1
C ry s ta l
O s c illa to r
PW DN
VREF
B ia s
C ir c u it
V re f
G e n e ra to r
R T /G T E S T
DV
DVB
S te e r in g C o n tr o l C ir c u it
VP
O PA
VN
GS
P r e - F ilte r
L o w G ro u p
F ilte r
H ig h G r o u p
F ilte r
D0
L a tc h
F re q u e n c y
C ode
&
D1
D e te c to r
D e te c to r
O u tp u t
B u ffe r
D2
D3
IN H
OE
Rev. 1.00
1
March 30, 2006