MT8870D/MT8870D-1

4-19

‡ Typical figures are at 25 °C and are for design aid only: not guaranteed and not subject to production testing.

1. dBm= decibels above or below a reference power of 1 mW into a 600 ohm load.

2. Digit sequence consists of all DTMF tones.

3. Tone duration= 40 ms, tone pause= 40 ms.

4. Signal condition consists of nominal DTMF frequencies.

5. Both tones in composite signal have an equal amplitude.

6. Tone pair is deviated by ±1.5 %± 2 Hz.

7. Bandwidth limited (3 kHz ) Gaussian noise.

8. The precise dial tone frequencies are (350 Hz and 440 Hz) ± 2 %.

9. For an error rate of better than 1 in 10,000.

10. Referenced to lowest level frequency component in DTMF signal.

11. Referenced to the minimum valid accept level.

12. Referenced to Fig. 10 input DTMF tone level at -25dBm (-28dBm at GS Pin) interference frequency range between 480-3400Hz.

13. Guaranteed by design and characterization.

Figure 10.

Characteristics

Sym

Min

Max

Units

Notes*

1

Valid input signal levels (each

tone of composite signal)

-31

+1

dBm

1,2,3,5,6,9

21.8

869

2

Input Signal Level Reject

-37

dBm

1,2,3,5,6,9

10.9

3

Negative twist accept

8

dB

2,3,6,9,13

4

Positive twist accept

8

dB

2,3,6,9,13

5

Frequency deviation accept

±1.5%± 2 Hz

2,3,5,9

6

Frequency deviation reject

±3.5%

2,3,5,9

7

Third zone tolerance

-18.5

dB

2,3,4,5,9,12

8

Noise tolerance

-12

dB

2,3,4,5,7,9,10

9

Dial tone tolerance

+22

dB

2,3,4,5,8,9,11