MX105ADW CMLMICRO [CML Microcircuits], MX105ADW Datasheet - Page 7

• Manufacturer Part Number: MX105ADW
• Description: Tone Detector
• Manufacturer: CMLMICRO [CML Microcircuits]

Tone Detector
5. Application
The external components shown in Figure 2 are used to adjust the various performance parameters of the MX105A. The
signal-to-noise performance, response time and signal bandwidth are all interrelated factors which should be optimized to
meet the requirements of the application.
By selecting component values in accordance with the following formulas, optimum circuit performance is obtained for any
given application.
First define the following application parameters:
Note: Using this information the appropriate component values can be calculated, and the signal-to-noise performance
5.1 Method for Calculating External Component Values
The examples on the following pages demonstrate the calculation of component values for any given application. For the
purpose of the examples, the values below are used:
5.2 Define f
The components R1, C1
shown below, the frequency of 2800 Hz corresponds to a capacitor value of 220pF and a resistor value of 385 k . This
resistance can be achieved with a 300 k
C1
capacitance.
5.3 Calculate Minimum Usable Bandwidth
Minimum Usable Bandwidth (MUBW) is the TOTAL bandwidth required for the following:
Note: Add A, B and C and express as TOTAL bandwidth, not as a ± percentage (%) value.
5.4 Calculate The Recommended Operating Bandwidth
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B. The MX105A Minimum Usable Bandwidth (MUBW). This is obtained by taking into account the worst case
C. The maximum permissible MX105A response time.
A. f
B.
C. Maximum allowed response time = 50ms
D. Minimum input signal amplitude = 200 mV
A. The center frequency to be detected (f
D. The minimum input signal amplitude.
A. Input signal frequency tolerance
B. MX105A f
C. MX105A f
A
and C1
tolerances on the input tone frequency and variations in the MX105A f
effect of the MX105A and its supporting components.
0
TEMP = 100 °C,
can be read from a chart. Do not add large safety margins for response time and minimum signal amplitude;
reasonable margins are already included in the formulas. Excessive margins may result in reduced noise immunity.
= 2800 Hz
B
should include 10-20pF parasitic capacitance due to the device and its package plus any board parasitic
0
0
0
temperature coefficient (T
supply voltage coefficient (V
A
V
and C1
DD
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= 1V,
B
set the free running frequency of the VCO and therefore the f
MUBW
MUBW = 0.5 + 0.01
f
f
0
IN
C
fixed resistor for R1
= 0.5%
0
= 100 ppm/ C)
where : K
C
).
BW
K R1(C1
=
= 5000 ppm/V)
RMS
f
0
10 MUBW
.
+ T
1
R1
A
2
7
C
C1 )
=
=
TEMP
B
F
100 + 0.5
and for R1
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2.1 ± 5%
(R1
10 2
R1 C1
+ V
2
F
+ R1
C
A
V
V
6%
V
0
)
a 100 k potentiometer. The capacitance of
due to supply voltage and any temperature
1 = 2%
2Kf
1
0
MX105A PRELIMINARY INFORMATION
0
of the MX105A. As
Doc.# 20480133.003