MT8870 Mitel Networks Corporation, MT8870 Datasheet

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MT8870

Manufacturer Part Number
MT8870
Description
ISO2-CMOS Integrated DTMF Receiver
Manufacturer
Mitel Networks Corporation
Datasheet

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Features
Applications
PWDN
IN +
Complete DTMF Receiver
Low power consumption
Internal gain setting amplifier
Adjustable guard time
Central office quality
Power-down mode
Inhibit mode
Backward compatible with
MT8870C/MT8870C-1
Receiver system for British Telecom (BT) or
CEPT Spec (MT8870D-1)
Paging systems
Repeater systems/mobile radio
Credit card systems
Remote control
Personal computers
Telephone answering machine
IN -
GS
Power
Chip
OSC1
VDD
Chip
Bias
Circuit
Bias
VSS
Tone
Filter
Dial
OSC2
Figure 1 - Functional Block Diagram
High Group
Low Group
Filter
Filter
to all
Chip
Clocks
Zero Crossing
Detectors
VRef
Buffer
ISO
VRef
Description
The MT8870D/MT8870D-1 is a complete DTMF
receiver integrating both the bandsplit filter and
digital decoder functions. The filter section uses
switched capacitor techniques for high and low
group filters;
techniques to detect and decode all 16 DTMF tone-
pairs into a 4-bit code. External component count is
minimized by on chip provision of a differential input
amplifier, clock oscillator and latched three-state bus
interface.
St/GT
2
-CMOS
MT8870DE/DE-1
MT8870DC/DC-1
MT8870DS/DS-1
MT8870DN/DN-1
MT8870DT/DT-1
St
GT
ESt
Detection
Algorithm
Digital
INH
MT8870D/MT8870D-1
Integrated DTMF Receiver
the decoder uses digital counting
Ordering Information
Steering
Logic
-40 °C to +85 °C
ISSUE 3
STD
Converter
and Latch
18 Pin Plastic DIP
18 Pin Ceramic DIP
18 Pin SOIC
20 Pin SSOP
20 Pin TSSOP
Code
TOE
May1995
Q1
Q2
Q3
Q4
4-11

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MT8870 Summary of contents

Page 1

... MT8870DE/DE-1 MT8870DC/DC-1 MT8870DS/DS-1 MT8870DN/DN-1 MT8870DT/DT-1 Description The MT8870D/MT8870D complete DTMF receiver integrating both the bandsplit filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; techniques to detect and decode all 16 DTMF tone- pairs into a 4-bit code ...

Page 2

... MT8870D/MT8870D IN IN VRef 5 14 INH 13 PWDN 6 12 OSC1 7 11 OSC2 8 10 VSS 9 18 PIN CERDIP/PLASTIC DIP/SOIC Pin Description Pin # Name IN+ Non-Inverting Op-Amp (Input IN- Inverting Op-Amp (Input Gain Select. Gives access to output of front end differential amplifier for connection of feedback resistor ...

Page 3

... AAA AAA AAA 1kHz FREQUENCY (Hz) Figure 3 - Filter Response MT8870D/MT8870D =(RC)In GTA DD TSt t =(RC)In[V /(V -V GTP DD DD TSt (see Figure AAAA AAA AAA ...

Page 4

... MT8870D/MT8870D-1 condition is maintained (ESt remains high) for the validation period ( reaches the threshold GTP the steering logic to register the tone pair, TSt latching its corresponding 4-bit code (see Table 1) into the output latch. At this point the GT output is activated and drives ...

Page 5

... It inhibits the detection of tones representing characters and D. The output code will remain the same as the previous detected code (see Table 1). Differential Input Configuration The input arrangement of the MT8870D/MT8870D-1 provides a differential-input operational amplifier as well as a bias source (V ) which is used to bias the Ref inputs at mid-rail ...

Page 6

... This condition can be attained by choosing a suitable values provide 3 dB attenuation, such that -34 dBm input signal will correspond to -37 dBm at the gain setting pin GS of MT8870D-1. As shown in the diagram, the component values of R and C are the guard time 3 ...

Page 7

... 2.2 2.4 TSt -0. 1.0 2 0.4 0 2.3 2.5 Ref MT8870D/MT8870D-1 Min Max 7 V -0 -65 +150 500 ) unless otherwise stated. SS Max Units Test Conditions 5.25 V +85 °C MHz % +85°C, unless otherwise stated. Max Units Test Conditions 25 µA PWDN fc=3 ...

Page 8

... DC open loop voltage gain 7 Unity gain bandwidth 8 Output voltage swing 9 Maximum capacitive load (GS) 10 Resistive load (GS) 11 Common mode range MT8870D AC Electrical Characteristics Characteristics Valid input signal levels (each 1 tone of composite signal) 2 Negative twist accept 3 Positive twist accept 4 Frequency deviation accept ...

Page 9

... MT8870D-1 AC Electrical Characteristics Characteristics Valid input signal levels (each 1 tone of composite signal) 2 Input Signal Level Reject 3 Negative twist accept 4 Positive twist accept 5 Frequency deviation accept 6 Frequency deviation reject 7 Third zone tolerance 8 Noise tolerance 9 Dial tone tolerance ‡ Typical figures are at 25 °C and are for design aid only: not guaranteed and not subject to production testing. ...

Page 10

... PTE t 300 PTD 3.5759 3.5795 3.5831 C t LHCL t HLCL equals time from PDWN going low until ESt going high MT8870D/MT8870D-1 IN IN- St/ ESt V StD Ref INH Q4 Q3 PDWN Q2 OSC 1 Q1 OSC 2 V TOE SS ‡ Max ...

Page 11

... ISO -CMOS REC ID TONE TONE # GTA GTP QStD # n t PSrD -Q TO ITS HIGH IMPEDANCE STATE Figure 11 - Timing Diagram MT8870D/MT8870D TONE # TSt HIGH IMPEDANCE # ( PTE t PTD 4-21 ...

Page 12

... MT8870D/MT8870D-1 NOTES: 4-22 2 ISO -CMOS ...

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