Data Sheet

AS2574B

Rev. 1

22

Jan. 1995

Parameter

Symbol

Min

Typ

Max

Unit

Condition

Clock Startup Time

Ts

5

ms

Key Debounce Time

Td

14

18

ms

HS Debounce Time

Ths

21

26

ms

CD Reset Delay Time

Tr

2

sec

DTMF

Tone Level, High Group

Vol

- 12.4

- 10.9

- 9.4

dBm

RL = 15 k

Ω

Preemphasis

2

2.5

2.8

dBm

RL = 15 k

Ω

Distortion

- 26

dBr

RL = 15 k

Ω, note 3

Tone Duration

Ttd

80

82.3

85

ms

Note 1

Inter Tone Pause

Titp

80

82.3

85

ms

Note 1

Tone Rise/Fall Time

Ttr

5

ms

Note 2

LD

Dial Rate

10

pps

± 5%

Make/Break Period

Tm/Tb

33/66

ms

± 5%

(diode option)

40/60

ms

± 5%

Inter Digit Pause

Tidp

753

785

ms

Pre Digit Pause

Tpre

55

57

ms

Post Digit Pause

Tpo

55

57

ms

Flash

Duration

Tfd

100

101.2

103

ms

No diode 2

600

620

ms

With diode 2

Earth Recall

Tg

Duration

500

510

ms

Automatic Access Pause

Tap

Short

4

4.1

4.2

sec

DT = Hi-Z

Long

7.9

8

8.1

sec

DT = Low

Termination

1.15

1.2

1.25

sec

DT = High

Mute Overhang

Tmo

182

200

223

ms

MR/MT Hold Over

Tho

18

27

ms

Tone Burst

Frequency

Fb

700

800

Hz

Output Level

Vtb

-13

-11

-9

dBm

Tone Duration

Ttb

80

85

ms

Inter Tone Pause (LS)

Titb1

7

8

9

sec

Inter Tone Pause (Mute)

Titp2

1.8

2

2.2

sec

Time-out

Tto

7.7

8

8.2

sec

SignallingCharacteristics

Defaults conditions: Recommended Operating Range

Note 1: The values are valid during automatic dialling and are minimum values during manual dialling, i.e. the tones will continue

as long as the key is depressed.

Note 2: The rise time is the time from valid key detection (key has been debounced) till the tone amplitude has reached 90 % of its

final value.

Note 3: Relative to high group.