CML Semiconductor Products
PRODUCT INFORMATION
FX621
Low-Power Subscriber Private
Metering (SPM) Detector
Publication D/621/2 June 1991
Provisional Issue
Features/Applications
Meets 12kHz and 16kHz SPM
Specifications
Adjustable Input Gain
PABX, Payphone and Telephone
Applications
Low-Power CMOS [ 3.5 – 5 Volt
Operation ]
General-Purpose Tone Detection
Tone Follower and SPM Packet
Detection Modes
XTAL
Crystal Oscillator Stability
XTAL/CLOCK
V DD
4.433619 MHz
OSCILLATOR
V SS
4.433619 MHz
V BIAS
1
SYSTEM SELECT 12/16 kHz
3
or 4
AMP
INPUT ( – )
–
AMP
INPUT (+)
"SYSTEM GAIN SET"
AMPLIFIER
FREQUENCY DIVIDERS
+
1
AMP OUTPUT
(GAIN SET)
DETECTOR
INPUT
MODE SELECT
2
554.203 kHz
or
738.937 kHz
LEVEL
DETECTOR
FREQUENCY
WINDOW
DETECTOR
FX621
OUTPUT RESET
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.
Pin Number
Function
DIL
FX621P
Quad
FX621LG/LS
1
1
Xtal/Clock: Input to the clock oscillator inverter. A single 4.433619MHz Xtal or external clock
pulse input is required (see Figure 2).
2
2
VDD: The positive supply rail. A single, stable supply in the range 3.5V to 5V is required.
3
5
Detector Input: “Schmitt Trigger” level detector circuitry whose input thresholds are set
internally and dependent on the applied VDD. For use with low signal-level systems this input
should be preceded by the “System Gain Set” amplifier. To use this input without the “System
Gain Set” amplifier, the components indicated in Figure 2 (inset) should be used with the
protection diodes (D1 - D4).
4
6
Amplifier Input (+):
5
7
Amplifier Input (–):
6
8
Amplifier Output: The output of the “System Gain Set” Amplifier, is used with gain setting
components. See Figures 1 and 2.
8
12
VSS: The negative supply rail, (GND).
9
13
VBIAS: The internal analogue bias pin, this point is at VDD/2 and requires to be externally
decoupled to VSS via capacitor C3.
10
14
Space Length Time: Active only in the ‘SPM Packet’ mode, this input, with an external RC
network, sets the minimum valid No-Tone (Space) period for the incoming packet using the
formula: tS = 0.7 (R6 x C5). If the ‘SPM Packet’ mode is not required these timing components
may be omitted. See Page 4.
11
17
Pulse Length Time: Active only in the ‘SPM Packet’ mode, this input, with an external RC
network, sets the minimum valid Tone period for the incoming packet using the formula:
tM = 0.7 (R5 x C4). If the ‘SPM Packet’ mode is not required these timing components may be
omitted. See Page 4.
12
18
Output Reset: This input is used only in the ‘SPM Packet’ mode. Once an SPM packet has
been detected and an output generated (logic “0”) from this device the output remains as set
until this input is strobed to a logic “0.” See Figure 3. This input has an internal 1MΩ pullup
resistor.
13
19
Mode Select: A control pin to select either the ‘Tone Follower’ mode or the ‘SPM Packet’ mode.
A logic “1” selects ‘Tone Follower’, a logic “0” selects ‘SPM Packet.’ This input has an internal
1MΩ pullup resistor (Tone Follower).
14
20
Output: The digital output of the SPM Detector. In the ‘Tone Follower’ mode a valid tone gives
a logic “0” and no-tone gives a logic “1.” Tonebursts and tone dropouts of less than 16 cycles
are ignored. In the ‘SPM Packet’ mode the output is set to a logic “0” when a valid ‘packet’ is
measured. The output remains as set until reset by a logic “0” at the Output Reset function,
see Figure 3.
15
23
System Select: A control pin to set the device to work on either a 12kHz (logic “1”) or 16kHz
(logic “0”) SPM system. This input has an internal 1MΩ pullup resistor (12kHz).
16
24
Xtal: The output of the clock oscillator inverter, see Figure 2.
7
3, 4, 9, 10,
11, 15, 16,
21, 22.
The positive and negative inputs to the “System Gain Set” Amplifier.
With single or differential inputs this amplifier and its external circuitry
can be used to provide the extra gain required to set the device to the
user’s National Level Specification. External diodes are used at both
inputs (if in use) to provide protection when the line input level exceeds
the supply rails (above the Absolute Maximum Rating).
If this device is used without this amplifier, the protection diodes should
be employed at the Detector Input. See Figure 2.
No internal connection – leave open circuit.
2
Application Information
The notes on these pages are intended to assist in calculating the external components required to operate the FX621 as an
SPM Detector.
DETECTOR INPUT
VDD
FX621P
PIN No.
X1
3
C9
XTAL
XTAL/CLOCK
R7
V BIAS
VBIAS
V DD
INSET
D2
D1
C1
DETECTOR INPUT
R1
AMP INPUT (+)
R2
R3
AMP OUTPUT
C7
V SS
D4
2
15
3
14
13
FX621P
5
x
D3
16
4
AMP INPUT (-)
C2
1
12
6
11
7
10
8
9
R5
SYSTEM SELECT
OUTPUT
MODE SELECT
OUTPUT RESET
C6
PULSE LENGTH
SPACE LENGTH
V BIAS
R4
V BIAS
R6
C4
C3
C5
C8
(a) Differential Input Configuration
V SS
Component References
Component
Reference
Component
R1
Note 4
C1
R2
Note 4
C2
R3
390kΩ ± 1.0%
C3
R4
390kΩ ± 1.0%
C4
R5
Note 5
C5
R6
Note 5
C6
R7
1.0MΩ
C7
D1 to D4 1N4148 or equivalent
C8
(small signal type)
C9
X1
4.433619MHz
V BIAS
Reference
Note 4
Note 4
1.0µF ± 20%
Note 5
Note 5
1.0µF ± 20%
12.0pF ± 10.0%
12.0pF ± 10.0%
0.1µF ± 10.0%
C7
D1
R3
"SYSTEM GAIN
SET" AMPLIFIER
5
C2
6
R2
D3
+
4
V BIAS
3
AMP
DETECTOR
OUTPUT
INPUT
C3
V SS
(b) Single Input Configuration
Fig.2 Recommended External Components
Gain Component Calculations
(1)
Calculate the FX621 sensitivity.
(4)
Calculate the gain/attenuation components for the
chosen gain.
Device Sensitivity – at the Detector Input (Figure 1) is
dependent upon the VDD value and is calculated as:
Device Sensitivity ≈ 0.2 x VDD
Gain Components – for a differential input:
R1 = R2
R3 = R4
(Vrms)
2 x √2
Gain =
(2)
Ascertain the required National {Minimum WillDecode} and [Maximum Will-Not Decode] Levels.
C8 = C7
C1 = C2
ZFeedback
(R4 //X(C8))
ZInput
(R1 + X(C1))
This calculation approximates as:
R1 ≈
(3)
Calculate the acceptable range of required Gain/
Attenuation for the levels in Note 2, using the “System Gain Set”
amplifier.
1.2 x (selected gain)
and
The gain requirement is calculated as :
R4
C1 ≈
1
2π x R1 x 6.0kHz
[Max] / {Min} Gain
[or]
=
Device Sensitivity
– using the nearest preferred value components.
The values of R1 and C1 have been calculated to give a highpass cut-off between the audio and SPM tone frequencies,
approximately 6kHz. C7 and C8 are anti-alias components and
are calculated for an approximate cut-off frequency of 32kHz.
{ Minimum Will-Decode Level }
[ Maximum Will-Not Decode Level ]
Choose a gain figure that meets both level requirements.
3
Application Information ......
(5)
(6)
Timing Components
In the ‘SPM Packet’ mode R5 and C4 set the minimum
'Tone' period (tM), R6 and C5 set the minimum 'Space'
period (tS), and are calculated as follows:
tM = 0.7(R5 x C4).
Protection Diodes
As most telephone systems operate at voltages in excess
of the Absolute Maximum Limits for damage, diodes D1 –
D4 are essential for device protection.
tS = 0.7(R6 x C5).
When calculating Tone and Space time settings the following
points should be taken into consideration:
(7)
(1)
(2)
(3)
Response and De-response times tR and tD.
Component tolerances can alter the calculation.
The MINIMUM expected pulse/space length must
be catered for.
Component Tolerances
The tolerances of external components used with this
device are dependent upon the required accuracy of the
gain and pulse period timings.
Timing
Figure 3 shows the FX621 output timing – Timing value limits are given on the “Specification” page.
Note – There is no reaction to pulses or drop-outs of less than the valid Response or De-response time.
TONE FOLLOWER MODE
TONE INPUT
NOTE
tD
tR
NOTE
tR
tD
OUTPUT
SPM PACKET MODE
TONE INPUT
tR
tD
tM
tR
tS
OUTPUT
OUTPUT RESET
t RESET
Fig.3 Output Timing
Example Values
– for the FX621 to operate with the West German (16kHz) 'FTZ' Specification.
(a) Min. 'Will Decode' Level
=
71.3 mV rms
(b) Max. 'Will Decode' Level
=
10.0 V rms
(c) Max. 'Will-Not Decode' Level
=
34.6 mVrms
(d) Device Sensitivity @ 3.5V VDD
≈
248.0 mVrms
Min. Gain Required
(d÷a)
≈
3.47
Max. Gain Allowed
(d÷c)
≈
7.17
=
4.7
Chosen Gain Figure
For a chosen gain figure of 4.7, a minimum Tone length
of 80ms, a minimum Space length of 135ms and a VDD
of 3.5V, the required component values are :
R1
R2
R3
R4
R5
R6
68kΩ
68kΩ
390kΩ
390kΩ
100kΩ
120kΩ
X1
4.433619MHz
Tolerances:
4
C1
C2
C3
C4
C5
C6
C7
C8
330pF
330pF
1.0µF
820nF
1.0µF
1.0µF
12pF
12pF
Resistors = ±1%. Capacitors = ±10%.
Specification
Absolute Maximum Ratings
Exceeding the maximum rating can result in device damage. Operation of the device outside the operating limits is not
implied.
Supply Voltage
Input Voltage at any pin (ref VSS = 0V)
Sink/source current (supply pins)
(other pins)
Total device dissipation @ TAMB 25°C
Derating
-0.3 to 7.0V
-0.3 to (VDD + 0.3V)
± 30mA
± 20mA
800mW Max.
10mW/°C
Operating temperature range:
FX621P/LG/LS
-30°C to + 70°C
Storage temperature range:
FX621P/LG/LS
-40°C to + 85°C
Operating Limits
All device characteristics are measured under the following conditions unless otherwise specified :
VDD = 3.5V
TAMB = 25°C
Xtal/Clock fC = 4.433619MHz
Audio level 0dB ref = 775mV rms
Characteristics
Static Values
Supply Voltage (VDD)
Supply Current (IDD)
Input Logic “1”
Input Logic “0”
Output Logic “1”
Output Logic “0”
Impedances
"Gain Set" Amplifier Input
"Gain Set" Amplifier Output
Analogue Detector Input
Digital Inputs
Digital Output
Dynamic Values
Sensitivity
Required Signal to Noise Ratio
Upper Detector Threshold
Lower Detector Threshold
Amplifier Input Offset
Xtal Oscillator Frequency
Frequency Discrimination
'Will-Decode' Frequency Limits
'Will-Not Decode' Frequency Limits
Timing Information – Fig.3
Valid Tone Burst Length (tM)
Valid Space Length (tS)
Tone Response Time (tR)
De-response Time (tD)
SPM Output Reset Time (tRESET)
Notes
System See Note
12kHz/16kHz
1, 2
7
2
2
12kHz
16kHz
12kHz
12kHz
16kHz
16kHz
12/16kHz
12/16kHz
12kHz
16kHz
12kHz
16kHz
12/16kHz
3, 4
4
5, 7
5, 7
6, 7
6, 7
4
1.
2.
3.
4.
Min.
Typ.
Max.
Unit
3.5
–
70.0
0
80.0
–
–
1.0
–
–
–
–
5.0
1.4
100
30.0
–
20.0
V
mA
% VDD
% VDD
% VDD
% VDD
1.0
–
1.0
0.5
–
–
–
–
1.0
–
–
10.0
–
–
10.0
MΩ
kΩ
MΩ
MΩ
kΩ
–
–
2.06
1.36
–
248
45.0
2.1
1.4
15.0
4.433619
–
–
2.14
1.44
–
mVrms
dB
V
V
mV
MHz
11.82
15.76
0
12.48
0
16.64
–
–
–
–
–
–
12.18
16.24
11.52
–
15.36
–
kHz
kHz
kHz
kHz
kHz
kHz
16.0
5.0
–
–
–
–
150.0
–
–
1.7
1.2
1.7
1.2
–
–
–
3.0
2.0
3.0
2.0
–
cycles
ms
ms
ms
ms
ms
ns
Device sensitivity at the Detector Input pin, or using the 'Gain Set' Amplifier at unity.
These values are quoted at 3.5 volt VDD, any supply variation will alter levels accordingly.
Tone Follower mode.
SPM Packet mode, in this mode the minimum valid Pulse (Space) length is programmable by means
of an RC network on the Pulse (Space) Length Time pin. If no RC network is used, the minimum
valid tone length reverts to 16 cycles.
5. The time for the circuit to recognize a valid 'Tone' in the Tone Follower mode.
6. The time for the circuit to recognize a valid 'No Tone' in the Tone Follower mode.
7. The FX621 is a low-power zero crossing detector without on-chip filtering, for use with a good
Signal-to-Noise ratio. The FX611 is recommended for high noise environments. If the supply current
requirement of the FX611 is unacceptable, separate external filters should be employed with the FX621.
5
Package Outlines
Handling Precautions
The FX621 is available in the package styles outlined
below. Mechanical package diagrams and
specifications are detailed in Section 10 of this
document.
Pin 1 identification marking is shown on the relevant
diagram and pins on all package styles number
anti-clockwise when viewed from the top.
The FX621 is a CMOS LSI circuit which includes input
protection. However precautions should be taken to
prevent static discharges which may cause damage.
FX621P 16-pin DIL Package
FX621LG 24-pin Package
NOT TO SCALE
NOT TO SCALE
Max. Body Length
Max. Body Width
Max. Body Length
Max. Body Width
10.49mm
7.59mm
10.25mm
10.25mm
FX621LS 24-lead Package
Ordering Information
FX621P
FX621LG
FX621LS
16-pin plastic DIL
24-pin quad plastic
encapsulated bent and
cropped
24-lead plastic leaded
chip carrier
NOT TO SCALE
Max. Body Length
Max. Body Width
CML does not assume any responsibility for the use of any circuitry described. No circuit patent licences are implied
and CML reserves the right at any time without notice to change the said circuitry.
10.40mm
10.40mm
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CML Product Data
In the process of creating a more global image, the three standard product semiconductor
companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc
(USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst
maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA)
Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML Microcircuits.
These companies are all 100% owned operating companies of the CML Microsystems Plc
Group and these changes are purely changes of name and do not change any underlying legal
entities and hence will have no effect on any agreements or contacts currently in force.
CML Microcircuits Product Prefix Codes
Until the latter part of 1996, the differentiator between products manufactured and sold from
MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX
respectively. These products use the same silicon etc. and today still carry the same prefixes.
In the latter part of 1996, both companies adopted the common prefix: CMX.
This notification is relevant product information to which it is attached.
Company contact information is as below:
CML Microcircuits
(UK)Ltd
CML Microcircuits
(USA) Inc.
CML Microcircuits
(Singapore)PteLtd
COMMUNICATION SEMICONDUCTORS
COMMUNICATION SEMICONDUCTORS
COMMUNICATION SEMICONDUCTORS
Oval Park, Langford, Maldon,
Essex, CM9 6WG, England
Tel: +44 (0)1621 875500
Fax: +44 (0)1621 875600
[email protected]
www.cmlmicro.com
4800 Bethania Station Road,
Winston-Salem, NC 27105, USA
Tel: +1 336 744 5050,
0800 638 5577
Fax: +1 336 744 5054
[email protected]
www.cmlmicro.com
No 2 Kallang Pudding Road, 09-05/
06 Mactech Industrial Building,
Singapore 349307
Tel: +65 7450426
Fax: +65 7452917
[email protected]
www.cmlmicro.com
D/CML (D)/1 February 2002