鈥?/div>
Paging systems
Repeater systems/mobile radio
Credit card systems
Remote control
Personal computers
Telephone answering machine
VDD
VSS
VRef
Description
The MT88L70 is a complete 3 Volt, 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. External
component count is minimized by on chip provision of
a differential input amplifier, clock oscillator and latched
three-state bus interface.
INH
PWDN
Bias
Circuit
VRef
Buffer
Q1
High Group
Filter
Dial
Tone
Filter
Low Group
Filter
Zero Crossing
Detectors
Digital
Detection
Algorithm
Code
Converter
and Latch
Q2
Q3
Q4
Chip Chip
Power Bias
IN +
IN -
GS
to all
Chip
Clocks
St
GT
Steering
Logic
OSC1
OSC2
St/GT
ESt
STD
TOE
Figure 1 - Functional Block Diagram
1
Zarlink Semiconductor Inc.
Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.
Copyright 1997-2005, Zarlink Semiconductor Inc. All Rights Reserved.