MT88L70 Datasheet, PDF (1/10 Pages) Mitel Networks Corporation – 3 Volt Integrated DTMF Receiver

ISO²-CMOS MT88L70
®
3 Volt Integrated DTMF Receiver
Features
• 2.7 - 3.6 volt operation
• Complete DTMF receiver
• Low power consumption
• Internal gain setting amplifier
• Adjustable guard time
• Central office quality
• Power-down mode
• Inhibit mode
• Functionally compatible with Mitel’s MT8870D
Applications
• Paging systems
• Repeater systems/mobile radio
• Credit card systems
• Remote control
• Personal computers
• Telephone answering machine
ISSUE 2
May 1995
Ordering Information
MT88L70AC 18 Pin Ceramic DIP
MT88L70AE
MT88L70AS
MT88L70AN
18 Pin Plastic DIP
18 Pin SOIC
20 Pin SSOP
MT88L70AT 20 Pin TSSOP
-40 °C to + 85 °C
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.
VDD VSS
VRef
INH
PWDN
Bias
Circuit
Chip Chip
Power Bias
IN +
Dial
Tone
IN -
Filter
GS
VRef
Buffer
High Group
Filter
Zero Crossing
Detectors
Low Group
Filter
Digital
Detection
Algorithm
Code
Converter
and Latch
to all
Chip
Clocks
St
Steering
GT
Logic
OSC1
OSC2
St/GT
ESt
STD
TOE
Figure 1 - Functional Block Diagram
Q1
Q2
Q3
Q4
4-23