Datasheet

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Zarlink Semiconductor Inc.

Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.

Features

• 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

Applications

• 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

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;

the decoder uses digital counting techniques to detect

and decode all 16 DTMF tone-pairs into a 4-bit code.

October 2006

Ordering Information

MT8870DE 18 Pin PDIP Tubes

MT8870DS 18 Pin SOIC Tubes

MT8870DN 20 Pin SSOP Tubes

MT8870DSR 18 Pin SOIC Tape & Reel

MT8870DNR 20 Pin SSOP Tape & Reel

MT8870DN1 20 Pin SSOP* Tubes

MT8870DE1 18 Pin PDIP* Tubes

MT8870DS1 18 Pin SOIC* Tubes

MT8870DNR1 20 Pin SSOP* Tape & Reel

MT8870DSR1 18 Pin SOIC* Tape & Reel

MT8870DE1-1 18 Pin PDIP* Tubes

MT8870DS1-1 18 Pin SOIC* Tubes

MT8870DSR1-1 18 Pin SOIC* Tape & Reel

*Pb Free Matte Tin

-40°C to +85°C

MT8870D/MT8870D-1

ISO

-CMOS Integrated DTMF Receiver

Data Sheet

Figure 1 - Functional Block Diagram

PWDN

IN +

IN -

OSC1 OSC2 St/GT ESt STD TOE

VDD VSS VRef INH

Bias

Circuit

Dial

Tone

Filter

High Group

Filter

Low Group

Filter

Digital

Detection

Algorithm

Code

Converter

and Latch

Steering

Logic

Chip

Power

Chip

Bias

VRef

Buffer

Zero Crossing

Detectors

to all

Chip

Clocks

Summary of content (19 pages)

PAGE 1
ISO2 MT8870D/MT8870D-1 -CMOS Integrated DTMF Receiver Data Sheet Features October 2006 • 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 Ordering Information MT8870DE MT8870DS MT8870DN MT8870DSR MT8870DNR MT8870DN1 MT8870DE1 MT8870DS1 MT8870DNR1 MT8870DSR1 MT8870DE1-1 MT8870DS1-1 MT8870DSR1-1 Applications Tubes Tubes Tubes Tape
PAGE 2
MT8870D/MT8870D-1 Data Sheet External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface.
PAGE 3
MT8870D/MT8870D-1 Data Sheet Pin Description Pin # Name Description 19 St/GT Steering Input/Guard time (Output) Bidirectional. A voltage greater than VTSt detected at St causes the device to register the detected tone pair and update the output latch. A voltage less than VTSt frees the device to accept a new tone pair. The GT output acts to reset the external steering time-constant; its state is a function of ESt and the voltage on St. 20 VDD Positive power supply (Input). +5 V typical.
PAGE 4
MT8870D/MT8870D-1 Data Sheet Decoder Section Following the filter section is a decoder employing digital counting techniques to determine the frequencies of the incoming tones and to verify that they correspond to standard DTMF frequencies. A complex averaging algorithm protects against tone simulation by extraneous signals such as voice while providing tolerance to small frequency deviations and variations.
PAGE 5
MT8870D/MT8870D-1 Data Sheet The value of tDP is a device parameter (see Figure 11) and tREC is the minimum signal duration to be recognized by the receiver. A value for C of 0.1 µF is recommended for most applications, leaving R to be selected by the designer.
PAGE 6
MT8870D/MT8870D-1 Data Sheet Different steering arrangements may be used to select independently the guard times for tone present (tGTP) and tone absent (tGTA). This may be necessary to meet system specifications which place both accept and reject limits on both tone duration and interdigital pause. Guard time adjustment also allows the designer to tailor system parameters such as talk off and noise immunity.
PAGE 7
MT8870D/MT8870D-1 C1 R1 MT8870D/ MT8870D-1 IN+ + INC2 R4 R5 R3 GS R2 VRef Differential Input Amplifier C1=C2=10 nF All resistors are ±1% tolerance. R1=R4=R5=100 kΩ All capacitors are ±5% tolerance. R2=60kΩ, R3=37.5 kΩ R3= R 2R5 R2+R5 VOLTAGE GAIN (Av diff)= R5 R1 INPUT IMPEDANCE R12+ (ZINDIFF) = 2 1 ωc 2 Figure 6 - Differential Input Configuration To OSC1 of next MT8870D/MT8870D-1 C X-tal OSC1 OSC2 OSC2 OSC1 C C=30 pF X-tal=3.
PAGE 8
MT8870D/MT8870D-1 Data Sheet Parameter Unit Resonator R1 Ohms 10.752 L1 mH .432 C1 pF 4.984 C0 pF 37.915 Qm - 896.37 ∆f % ±0.2% Table 2 - Recommended Resonator Specifications Note: Qm=quality factor of RLC model, i.e., 1/2ΠƒR1C1. Applications Receiver System for British Telecom Spec POR 1151 The circuit shown in Fig. 9 illustrates the use of MT8870D-1 device in a typical receiver system. BT Spec defines the input signals less than -34 dBm as the non-operate level.
PAGE 9
MT8870D/MT8870D-1 Data Sheet VDD C1 DTMF Input R1 R2 X1 C2 MT8870D-1 IN+ VDD IN- St/GT GS VRef StD INH Q4 PWDN Q3 OSC 1 Q2 OSC 2 VSS Q1 TOE R3 ESt NOTES: R1 = 102 KΩ ± 1% R2 = 71.5 KΩ ± 1% R3 = 390 KΩ ±1% C1,C2 = 100 nF ± 5% X1 = 3.579545 MHz ± 0.1% VDD = 5.0 V ± 5% Figure 9 - Single-Ended Input Configuration for BT or CEPT Spec 9 Zarlink Semiconductor Inc.
PAGE 10
MT8870D/MT8870D-1 Data Sheet Absolute Maximum Ratings† Parameter Symbol 1 DC Power Supply Voltage 2 Voltage on any pin VI 3 Current at any pin (other than supply) II 4 Storage temperature Min. Max. Units 7 V VDD+0.3 V 10 mA +150 °C 500 mW VDD VSS-0.3 -65 TSTG 5 Package power dissipation PD † Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. Derate above 75°C at 16 mW / °C. All leads soldered to board.
PAGE 11
MT8870D/MT8870D-1 Data Sheet DC Electrical Characteristics - VDD=5.0V± 5%, VSS=0V, -40°C ≤ TO ≤ +85°C, unless otherwise stated. Characteristics 11 12 13 14 15 O U T P U T S Sym. Typ.‡ Min. Max. Units Test Conditions VSS+0.0 3 V No load V No load Low level output voltage VOL High level output voltage VOH VDD0.03 Output low (sink) current IOL 1.0 2.5 mA VOUT=0.4 V Output high (source) current IOH 0.4 0.8 mA VOUT=4.6 V VRef output voltage VRef 2.3 2.5 2.
PAGE 12
MT8870D/MT8870D-1 Data Sheet MT8870D AC Electrical Characteristics -VDD=5.0V ±5%, VSS=0V, -40°C ≤ TO ≤ +85°C, using Test Circuit shown in Figure 10. Characteristics Sym. Min. Typ.‡ Max. Units Notes* -29 +1 dBm 1,2,3,5,6,9 27.5 869 mVRMS 1,2,3,5,6,9 1 Valid input signal levels (each tone of composite signal) 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.
PAGE 13
MT8870D/MT8870D-1 Data Sheet MT8870D-1 AC Electrical Characteristics -VDD=5.0V±5%, VSS=0V, -40°C ≤ TO ≤ +85°C, using Test Circuit shown in Figure 10. Characteristics Sym. Min. Typ.‡ Max. Units -31 +1 dBm 21.8 869 mVRMS Tested at VDD=5.0 V 1,2,3,5,6,9 1 Valid input signal levels (each tone of composite signal) 2 Input Signal Level Reject 3 Negative twist accept 4 Positive twist accept 5 Frequency deviation accept ±1.5%± 2 Hz 2,3,5,9 6 Frequency deviation reject ±3.
PAGE 14
MT8870D/MT8870D-1 Data Sheet AC Electrical Characteristics - VDD=5.0V±5%, VSS=0V, -40°C ≤ To ≤ +85°C, using Test Circuit shown in Figure 10. Sym. Min. Typ.‡ Max. Units Tone present detect time tDP 5 11 14 ms Note 1 Tone absent detect time tDA 0.5 4 8.
PAGE 15
MT8870D/MT8870D-1 Data Sheet VDD C1 DTMF Input R1 R2 X-tal C2 MT8870D/MT8870D-1 IN+ VDD IN- St/GT GS VRef StD INH Q4 PDWN Q3 OSC 1 Q2 OSC 2 VSS Q1 TOE R3 ESt NOTES: R1,R2=100 KΩ ± 1% R3=300 KΩ ± 1% C1,C2=100 nF ± 5% X-tal=3.579545 MHz ± 0.1% Figure 10 - Single-Ended Input Configuration 15 Zarlink Semiconductor Inc.
PAGE 16
MT8870D/MT8870D-1 Data Sheet D A EVENTS B C tREC tREC E TONE #n + 1 tDP G tDO tID TONE #n Vin F TONE #n + 1 tDA ESt tGTA tGTP VTSt St/GT tPQ Q1-Q4 tQStD #n DECODED TONE # (n-1) HIGH IMPEDANCE # (n + 1) tPSrD StD tPTD TOE tPTE EXPLANATION OF EVENTS A) TONE BURSTS DETECTED, TONE DURATION INVALID, OUTPUTS NOT UPDATED.
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