4-18

‡ 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. Guaranteed by design and characterization.

Gain Setting Amplifier

Characteristics

Sym

Min

Max

Units

Test Conditions

1

Input leakage current

100

nA

2

Input resistance

10

M

Ω

3

Input offset voltage

25

mV

4

Power supply rejection

PSRR

50

dB

1 kHz

5

Common mode rejection

CMRR

40

dB

0.75 V

≤ V

6

DC open loop voltage gain

32

dB

7

Unity gain bandwidth

0.30

MHz

8

Output voltage swing

4.0

Load

≥ 100 kΩ to V

9

Maximum capacitive load (GS)

100

pF

10

Resistive load (GS)

50

k

Ω

11

Common mode range

2.5

No Load

Figure 10.

Characteristics

Sym

Min

Max

Units

Notes*

1

Valid input signal levels (each

tone of composite signal)

-29

+1

dBm

1,2,3,5,6,9

27.5

869

1,2,3,5,6,9

2

Negative twist accept

8

dB

2,3,6,9,12

3

Positive twist accept

8

dB

2,3,6,9,12

4

Frequency deviation accept

±1.5% ± 2 Hz

2,3,5,9

5

Frequency deviation reject

±3.5%

2,3,5,9

6

Third tone tolerance

-16

dB

2,3,4,5,9,10

7

Noise tolerance

-12

dB

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

8

Dial tone tolerance

+22

dB

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