Product Description

MT8870 Tone Decoder is a commonly used multi-frequency decoding IC developed and produced by MITEL. This circuit can receive DTMF signals and is a complete DTMF receiver. After receiving the DTMF signal, it divides the signal into high-frequency band and low-frequency band internally, and sends this signal to the digital decoder, and then sends the signal to the digital decoder to decode the key value, and then outputs the decoded key value in binary form to the external shared Bus through four lines (Q1, Q2, Q3, Q4). The MT8870 pin description is shown in Table 1 and the internal structure is shown in Figure 2. It is worth mentioning that when MT8870 decodes a key value and outputs it to the outside, its STD pin will rise from low state to high state, and then drop to low state after a period of time. We can use this feature to detect that there is a signal on this pin and immediately read the value generated by the Q1-Q4 pins into the CPU, and then decode the phone key value.

Product Introduction  

1. Onboard MT8870 multi-frequency decoding chip

2. Onboard voice input interface

3. Onboard 5 LED indicators for easy viewing of output status

4. The main pins of the chip are basically connected

Product Parameters

1. Onboard MT8870 complex frequency decoding chip;

2. Onboard voice input interface;

3. Onboard 5 LED indicators for easy viewing of output status;

4. The main pins of the chip are basically brought out;

5. PCB size: 26.5*24.5 (mm);

6. Module operating voltage: DC 5V;

7. Module maximum operating current: 10mA;

8. Operating temperature: -65C~+150*C;

9. Module maximum power consumption: 500mW

Actual image of the product