CM8870/70C
CALIFORNIA MICRO DEVICES
CMOS Integrated DTMF Receiver
Features
Applications
• Full DTMF receiver
• PABX
• Less than 35mW power consumption
• Central office
• Industrial temperature range
• Mobile radio
• Uses quartz crystal or ceramic resonators
• Remote control
• Adjustable acquisition and release times
• Remote data entry
• 18-pin DIP, 18-pin DIP EIAJ, 18-pin SOIC, 20-pin
PLCC
• Call limiting
O
bs
Pr o
od le
uc te
t
• Telephone answering systems
• CM8870C
• Paging systems
— Power down mode
— Inhibit mode
— Buffered OSC3 output (PLCC package only)
• CM8870C is fully compatible with CM8870 for 18-pin
devices by grounding pin 5 and pin 6.
Product Description
tone rejection. The CM8870/70C decoder uses digital
counting techniques for the detection and decoding of all
16 DTMF tone pairs into a 4-bit code. This DTMF
receiver minimizes external component count by providing an on-chip differential input amplifier, clock generator, and a latched three-state interface bus. The on-chip
clock generator requires only a low cost TV crystal or
ceramic resonator as an external component.
The CAMD CM8870/70C provides full DTMF receiver
capability by integrating both the band-split filter and
digital decoder functions into a single 18-pin DIP, SOIC,
or 20-pin PLCC package. The CM8870/70C is manufactured using state-of-the-art CMOS process technology
for low power consumption (35mW, MAX) and precise
data handling. The filter section uses a switched capacitor technique for both high and low group filters and dial
Block Dia g ra m
VSS
VDD
VREF
INH
–
BIAS
CIRCUIT
PD
CHP
POWER
IN+
Q1
CHP
BIAS
CHIP
REF
DIAL
TONE
FILTER
+
IN–
+
–
HIGH
GROUP
FILTER
Q2
ZERO
CROSSING DETECTORS
DIGITAL
DETECTION
ALGORITHM
CODE
CONVERTER
AND
LATCH
Q3
LOW
GROUP
FILTER
GS
Q4
TO ALL
CHIP
CLOCKS
St
GT
OSC 1
OSC 2
OSC 3
St/GT
ESt
STEERING
LOGIC
StD
TOE
C1581000
© 2001 California Micro Devices Corp. All rights reserved.
215 Topaz Street, Milpitas, California 95035
12/18/2001
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
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