MAX9038BABTT Просмотр технического описания (PDF) - Maxim Integrated

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MAX9038BABTT

Micropower, Single-Supply, UCSP/SOT23 Comparator + Precision Reference ICs

Maxim Integrated 

MAX9038–MAX9043/

MAX9050–MAX9053

Micropower, Single-Supply, UCSP/SOT23

Comparator + Precision Reference ICs

VIN

IN+

10kΩ

IN-

0.1µF

VCC

VCC

OUT

MAX9038–MAX9043

MAX9050–MAX9053

VEE

Figure 2. Time Averaging of the Input Signal for Data Recovery

VT=H

2.5

+

2.5







R2

R1 + R2







and

= VTL

2.5

1



−

R2

R1 + R2







4) Select R2. In this example, we will choose 1kΩ.

5) Select VHYS. In this example, we will choose 50mV.

6) Solve for R1:

VHYS

=

VCC







R2

R1 + R2







0.050

=

5

 1000

R1 + 1000







where R1 ≈ 100kΩ, VTH = 2.525V, and VTL = 2.475V.

Board Layout and Bypassing

Power-supply bypass capacitors are not typically needed,

but would be called for in cases where supply imped-

ance is high, supply leads are long, or excessive noise is

expected on the supply lines. Use 100nF bypass capaci-

tors under these conditions. Minimize signal trace lengths

to reduce stray capacitance.

Reference Output/Load Capacitance

The MAX9038/MAX9039/MAX904_/MAX905_ do not

require an output capacitor on REF for frequency stability.

They are stable for capacitive loads up to 4.7nF. However,

in applications where the load or the supply can experience

step changes, an output capacitor will reduce the amount

of overshoot (or undershoot) and assist the circuit’s tran-

sient response. When an application is not subject to tran-

sient conditions, the REF capacitor can be omitted.

Biasing for Data Recovery

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:

fCAR

>>

1

2πR1C1

where fCAR is the fundamental carrier frequency of the

digital data stream.

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