MAX9031 Maxim, MAX9031 Datasheet - Page 7

• Manufacturer Part Number: MAX9031
• Description: The MAX9030/MAX9031/MAX9032/MAX9034 single/dual/quad comparators are optimized for single-supply applications from +2
• Manufacturer: Maxim

Figure 1. Additional Hysteresis
1) Find the trip points of the comparator using these
2) The hysteresis band will be:
3) In this example, let V
4) Select R2. In this example, we will choose 1kΩ.
5) Select V
6) Solve for R1.
The above-described design procedure assumes rail-
to-rail output swing. If the output is significantly loaded,
the results should be corrected.
formulas:
where V
parator switches its output from high to low as V
rises above the trip point. V
age at which the comparator switches its output from
low to high as V
and
where R1 ≈ 100kΩ, V
V
V
REF
IN
V
TH
V
HYS
R2
0.050V = 5(1000Ω/(R1 + 1000Ω))V
= V
V
HYS
TH
V
TH
V
TL
= V
is the threshold voltage at which the com-
V
REF
TL
. In this example, we will choose 50mV.
= 2.5V + 2.5(R2 / (R1 + R2))V
HYS
= V
TH
= 2.5[1 - (R2 / (R1 + R2))]
_______________________________________________________________________________________
+ [((V
IN
R1
Low-Cost, Ultra-Small, Single/Dual/Quad
IN+
IN-
REF
= V
- V
drops below the trip point.
TL
(1 - (R2 / (R1 + R2))]
DD
DD
TH
DD
= V
(R2 / (R1 + R2))
= +5V and V
= 2.525V, and V
- V
DD
REF
V
V
V
DD
TL
DD
SS
(R2 / (R1 + R2))
)R2) / (R1 + R2)
is the threshold volt-
MAX9031
REF
OUT
TL
= +2.5V.
= 2.475V.
Single-Supply Comparators
IN
Use 100nF bypass as a starting point. Minimize signal
trace lengths to reduce stray capacitance. Minimize the
capacitive coupling between IN- and OUT. For slow-
moving input signals (rise-time > 1ms), use a 1nF
capacitor between IN+ and IN-.
Digital data is often embedded into a bandwidth and
amplitude-limited analog path. Recovering the data can
be difficult. Figure 2 compares the input signal to a
time-averaged version of itself. This self-biases the
threshold to the average input voltage for optimal noise
margin. Even severe phase distortion is eliminated from
the digital output signal. Be sure to choose R1 and C1
so that:
where ƒ
digital data stream.
Figure 2. Time Averaging of the Input Signal for Data Recovery
V
IN
CAR
10kΩ
is the fundamental carrier frequency of the
0.1µF
ƒ
CAR
Board Layout and Bypassing
Biasing for Data Recovery
>> 1 / (2
IN+
IN-
π
V
R1C1)
V
DD
SS
V
DD
MAX9031
OUT
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