NTE1731 데이터 시트보기 (PDF) - NTE Electronics

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NTE1731

Integrated Circuit CMOS 10 Number Pulse Dialer

NTE Electronics 

that the input is valid. Keyboard bounce is ignored for 32ms after the initial key down is detected.

A key input is accepted if it is valid after this initial debounce time. This scheme allows any valid key

input to be recognized within 40ms of the initial key closure.

GND (Pin6)

Negative power supply pin.

Oscillator (Pins7 and Pin8)

The oscillator is formed by using a 480kHz ceramic resonator and two capacitors.

Make/Break Select (Pin9)

The Make/Break ratio may be selected by connecting this pin to either VDD or GND, Table 1 indicates

the two popular ratios from which the user can choose.

Table 1

Level of Pin9

VDD (Pin1)

GND (Pin6)

Make

40%

32%

Break

60%

68%

Mute Output (Pin10)

Pin 10 is the output of an open–drain N–channel transistor, It provides the logic necessary to mute

the network while the telephone line is being pulled.

Hook Switch Input (Pin15)

The Hook Switch input pin requires an external pull–up resistor to the positive supply. A VDD input

puts the circuit into On–Hook mode, while a GND inputs puts it into OFF–Hook or dialing mode.

Pulse Output (Pin16)

The Pulse Output pin is a N–channel open drain output for driving an external transistor, this external

transistor is used to switch the loop current in a telephone line.

Pin Connection Diagram

VDD 1

Test 2

Column Input 3

Column Input 4

Column Input 5

GND 6

OSC Input 7

OSC Output 8

16 Pulse Output

15 Hook Switch

14 Row Input

13 Row Input

12 Row Input

11 Row Input

10 Mute Output

9 Make/Break Select

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