CML Semiconductor Products
PRODUCT INFORMATION
FX621
Features/Applications
Meets 12kHz and 16kHz SPM
Specifications
Low-Power CMOS [ 3.5 – 5 Volt
Operation ]
Tone Follower and SPM Packet
Detection Modes
Low-Power Subscriber Private
Metering (SPM) Detector
Publication D/621/2 June 1991
Provisional Issue
Adjustable Input Gain
PABX, Payphone and Telephone
Applications
General-Purpose Tone Detection
Crystal Oscillator Stability
XTAL
V
DD
XTAL/CLOCK
4.433619 MHz
OSCILLATOR
V
SS
4.433619 MHz
V
BIAS
3
or 4
AMP
INPUT ( – )
–
AMP
INPUT (+)
+
2
"SYSTEM GAIN SET"
AMPLIFIER
1
SYSTEM SELECT 12/16 kHz
FREQUENCY DIVIDERS
1
MODE SELECT
FX621
AMP OUTPUT
(GAIN SET)
554.203 kHz
or
738.937 kHz
LEVEL
DETECTOR
FREQUENCY
WINDOW
DETECTOR
OUTPUT RESET
DETECTOR
INPUT
COUNTERS
AND
OUTPUT LOGIC OUTPUT
PULSE
LENGTH
TIME
SPACE
LENGTH
TIME
Fig.1 Internal Block Diagram
Brief Description
The FX621 is a single-chip, low-power CMOS tone
detector designed for use in both PABX and general
payphone applications for Subscriber Private Metering.
The Decode and Not-Decode band edges are
accurately defined by the use of an external
4.433619MHz crystal.
Operation to either of the 12kHz or 16kHz SPM
systems is pin programmable, with system amplitude
sensitivities and pulse-length timing being provided by
the use of external components.
The FX621 has 2 pin-selectable modes of operation:
1)
Tone Follower Mode.
A logic “0” is output whenever a tone of the correct
frequency and length is detected.
2)
SPM Packet Mode.
An output is obtained only when both the mark and
space timing criteria of an input SPM tone have been
fulfilled.
The FX621, which is available in plastic DIL and SMD
packages, requires only a single 3.5-volt (min.) power
supply, a 4.433619MHz crystal with external gain and
timing components to meet most SPM specifications.
CMLMICRO [ CML MICROCIRCUITS ]
