HT95R34 datasheet(37/59 Pages) HOLTEK

37 / 59 page

HT95R34

Rev. 1.10

February 18, 2009

DTMF Data Output Table

Low Group (Hz)

High Group (Hz)

Digit

D3, D2, D1, D0

697

1209

0001

697

1336

0010

697

1477

0011

770

1209

0100

770

1336

0101

770

1477

0110

852

1209

0111

852

1336

1000

852

1477

1001

941

1336

1010

941

1209

1011

941

1477

1100

697

(Note*)

1633

1101

770

(Note*)

1633

1110

842

(Note*)

1633

1111

941

(Note*)

1633

0000

(Note*): Available only when R_INH=0

Steering Control Circuit

The steering control circuit is used to measure the effective signal duration and for protecting against a valid signal drop

out. This is achieved using an analog delay which is implemented using an external RC time-constant, controlled by the

output line EST.

The timing diagram shows more details. The EST pin is normally low and will pull the RT/GT pin low via the external RC

network. When a valid tone input is detected, the EST pin will go high, which will in turn pull the RT/GT pin high through

the RC network.

When the voltage on RT/GT rises from 0 to VTRT, which is 2.35V for a 5V power supply, the input signal is effective, and

the corresponding code will be generated by the code detector. After D0~D3 have been latched, DV will go high. When

the voltage on RT/GT falls from VDD to VTRT, i.e. when there is no input tone, the DV output will go low, and D0~D3 will

maintain their present data until a next valid tone input is produced. By selecting suitable external RC values, the mini-

mum acceptable input tone duration, tACC, and the minimum acceptable inter-tone rejection, tIR, can be set. The values

of the external RC components, can be chosen using the following formula.

tACC=tDP+tGTP;

tIR=tDA+tGTA;

Where

tACC: Tone duration acceptable time

tDP: EST output delay time (

²L²®²H²)

tGTP: Tone present time

tIR: Inter-digit pause rejection time

tDA: EST outptu delay time (

²H²®²L²)

tGTA: Tone absent time

HT95R34 датащи(PDF) 37 Page - Holtek Semiconductor Inc

HT95R34 датащи(HTML) 37 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

датащи скачать

ссылки URL