DATA BULLETIN
CMX631A
Features
•
Detects 12kHz or 16kHz SPM
Frequencies
•
Tone Follower and Packet Mode
Outputs
•
High Speech-Band Rejection
Properties
•
Low Power Operation (3.0V < 0.8mA)
Low Voltage
SPM Detector
PRELIMINARY INFORMATION
Applications
•
Call Charge Applications on PABX Line
Cards
•
Complex and/or Simple telephone
Systems
•
Remote Telephone/Payphones
XTAL/CLOCK
XTAL/CLOCK
OSCILLATOR
XTAL
V
DD
V
BIAS
V
SS
SYSTEM (12kHz/16kHz)
INPUT AMP
CLOCK IN
CLOCK OUT
SYSTEM
CLOCK
DIVIDERS
TONE FOLLOWER
OUTPUT
TONE
FOLLOWER
LOGIC
SIGNAL IN (+)
AMP OUT
The CMX631A is a low-power, system-selectable Subscriber Pulse Metering (SPM) detector that indicates the
presence of both 12kHz or 16kHz telephone call-charge frequencies on a telephone line.
Deriving its input directly from the telephone line, input amplitude/sensitivities are component adjustable to the
user's national ‘Must/Must-Not Decode’ specifications via an on-chip input amplifier. The 12kHz and 16kHz
frequency limits are accurately defined by the use of an external 3.579545MHz telephone-system Xtal or
clock-pulse input.
The CMX631A demonstrates exceptional 12kHz and 16kHz performance in the presence of both voice and
noise. This device may operate from a single or differential analog signal input, from which two individual
logic outputs will be produced; a Tone Follower Output or a Packet Mode Output.
This system (12kHz/16kHz) selectable integrated circuit, requires a 2.7V to 5.5V power supply, which may be
line-powered, is available in the following packages: 24-pin SSOP (CMX631AD5), 16-pin SOIC
(CMX631AD4), and 16-pin PDIP (CMX631AP3). Additional package styles may be available to meet specific
design requirements.
© 1999 MX•COM Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
+
-
SIGNAL IN (-)
12kHz/16kHz
32
1
LEVEL DETECTOR
DIVIDER
PERIOD
MEASURE
PACKET MODE
OUTPUT
PACKET
TONE
LOGIC
+20dB
SYSTEM
www.mxcom.com Tele: 800 638-5577 336 744-5050
Fax: 336 744-5054
Doc. # 20480177.004
All trademarks and service marks are held by their respective companies.
Low Voltage SPM Detector
2
CMX631A PRELIMINARY INFORMATION
CONTENTS
Section
Page
1 Block Diagram................................................................................................................ 3
2 Signal List....................................................................................................................... 4
3 External Components.................................................................................................... 5
4 General Description....................................................................................................... 6
4.1
4.2
4.3
Tone Follower Mode............................................................................................................ 6
Packet Mode........................................................................................................................ 6
Sensitivity Setting ................................................................................................................ 6
4.3.1
4.3.2
Input Gain Calculation ............................................................................................................ 6
Input Gain Components ......................................................................................................... 8
4.4
‘WILL’/’WILL-NOT’ Detect Frequencies............................................................................... 8
5 Applications ................................................................................................................... 8
5.1
Input Configurations ............................................................................................................ 8
5.1.1
5.1.2
Protection Against High Voltages ........................................................................................... 8
Aliasing................................................................................................................................... 9
6 Performance Specification............................................................................................ 9
6.1
Electrical Specifications....................................................................................................... 9
6.1.1
6.1.2
6.1.3
Absolute Maximum Ratings.................................................................................................... 9
Operating Limits ................................................................................................................... 10
Operating Characteristics..................................................................................................... 10
6.2
Packages........................................................................................................................... 11
MX-COM, Inc. reserves the right to change specifications at any time and without notice.
© 1999 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050
Fax: 336 744-5054
Doc. # 20480177.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
Low Voltage SPM Detector
3
CMX631A PRELIMINARY INFORMATION
1 Block Diagram
XTAL/CLOCK
XTAL/CLOCK
OSCILLATOR
XTAL
V
DD
V
BIAS
V
SS
SYSTEM (12kHz/16kHz)
INPUT AMP
CLOCK IN
CLOCK OUT
SYSTEM
CLOCK
DIVIDERS
TONE FOLLOWER
OUTPUT
TONE
FOLLOWER
LOGIC
SIGNAL IN (+)
AMP OUT
© 1999 MX•COM Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
+
-
SIGNAL IN (-)
12kHz/16kHz
32
1
LEVEL DETECTOR
DIVIDER
PERIOD
MEASURE
PACKET MODE
OUTPUT
PACKET
TONE
LOGIC
+20dB
SYSTEM
Figure 1: Block Diagram
www.mxcom.com Tele: 800 638-5577 336 744-5050
Fax: 336 744-5054
Doc. # 20480177.004
All trademarks and service marks are held by their respective companies.
Low Voltage SPM Detector
4
CMX631A PRELIMINARY INFORMATION
2 Signal List
Packages
D5
1
D4/P3
1
Signal
Name
Xtal/Clock
Type
input
The input to the on-chip clock oscillator; for use with a
3.579545MHz Xtal in conjunction with the Xtal output; circuit
components are on-chip. When using a Xtal input, the Clock
Out pin should be connected directly to the Clock In pin. If a
clock pulse input is used at the Clock In pin, this (Xtal/Clock)
pin must be connected directly to V
DD
See Figure 2 and
Section 3.
The output of the on-chip clock oscillator inverter.
The buffered output of the on-chip-clock oscillator inverter. If a
Xtal input is used, this output should be connected directly to
the Clock In pin.
The 3.579545MHz clock pulse input to the internal clock
dividers. If an externally generated clock pulse is used, the
Xtal/Clock input pin should be connected to V
DD
. Reference
Section 3.
The output of the on-chip analog bias circuitry. Held internally
at V
DD
/2, this pin should be bypassed to V
SS
. See Figure 2.
Negative supply (GND).
The positive input to the input gain adjusting signal amplifier.
Reference Section 4.3 and 4.4.
The negative input to the input gain adjusting signal amplifier.
Reference Section 4.3 and 4.4.
The output of the input gain adjusting signal amplifier.
Reference Section 4.3 and 4.4.
This output provides a logic 0 for the period of a detected tone
and a logic 1 for a NOTONE detection. See Section 4.1 and
Figure 3.
This output provides a logic 0 for a detected tone and a logic 1
for NOTONE detection and will ignore a small fluctuation or
fade during the tone signal. See Section 4.2 and Figure 3.
This logic input selects the device operation to either 12kHz
(logic 1) or 16kHz (logic 0) SPM systems. This input has an
internal 1MΩ pull-up resistor (12kHz).
Positive supply. A single, stable power supply is required.
Critical levels and voltages within the CMX631A are dependent
upon this supply. This pin should be bypassed to V
SS
by a
capacitor mounted close to the pin. Note: If this device is line
powered, the resulting power supply must be stable. See
Section 5.1.1.
No internal connection; leave open circuit.
Description
4
5
2
3
XTAL
Clock Out
output
output
6
4
Clock In
input
8
12
13
17
18
19
7
8
9
10
11
13
V
BIAS
V
SS
Signal In +
Signal In -
Amp Out
Tone
Follower
Mode
Packet Mode
power
power
input
input
input
output
20
14
output
21
15
System
input
24
16
V
DD
power
2, 3, 7,
9, 10,
11, 14,
15, 16,
22, 23
5,6,12
N/C
Table 1: Signal List
© 1999 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050
Fax: 336 744-5054
Doc. # 20480177.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
Low Voltage SPM Detector
5
CMX631A PRELIMINARY INFORMATION
3 External Components
V
DD
XTAL/CLOCK
X1
XTAL
V
DD
C1
SYSTEM
PACKET MODE OUTPUT
TONE FOLLOWER OUTPUT
1
2
3
4
5
6
16
15
14
13
CLOCK OUT
CLOCK IN
CMX631A
D4/P3
12
11
10
9
AMP OUT
SIGNAL IN (-)
SIGNAL IN (+)
R4
R1
R2
R3
C3
C4
V
BIAS
V
SS
7
8
C2
Figure 2: Recommended External Components
R1
R2
R3
R4
Note 1
Note 1
Note 1
Note 1
R
FEEDBACK
R
IN(-)
R
IN(+)
R
BIAS
C1
C2
C3
C4
X1
Note 2, 3, 4
1.0µF
1.0µF
C
IN(-)
C
IN(+)
3.579545MHz
±20%
±20%
Table 2: Recommended External Components
Recommended External Component Notes:
1. When calculating input gain components, for correct operation R1 and R4 should always be
≥
33kΩ.
2. For best results, a crystal oscillator design should drive the clock inverter input with signal levels of at
least 40% of V
DD
, peak to peak. Tuning fork crystals generally cannot meet this requirement. To
obtain crystal oscillator design assistance, consult your crystal manufacturer.
3. The on-chip crystal circuitry includes a feedback resistor (nominally 2MΩ) between pins 1 and 2 and
load capacitors on pins 1 and 2 (nominally 10pF each, excluding package and board parasitics).
4. When using an external clock input, X1 should be removed, Pin 1 (Xtal/Clock) should be tied to V
DD
,
the Clock In and Clock Out jumper should be removed, and the external clock signal applied to Clock
In.
© 1999 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050
Fax: 336 744-5054
Doc. # 20480177.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
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