XR-2211 Ver la hoja de datos (PDF) - Exar Corporation

Número de pieza

componentes Descripción

Fabricante

XR-2211

FSK Demodulator Tone Decoder

Exar Corporation 

XR-2211

f) The input to the XR-2211 may sometimes be too sensitive to noise conditions on the input line. Figure 4 illustrates

a method of de-sensitizing the XR-2211 from such noisy line conditions by the use of a resistor, Rx, connected

from pin 2 to ground. The value of Rx is chosen by the equation and the desired minimum signal threshold level.

ǒ Ǔ VIN

minimum

(peak) +

Va–Vb + DV " 2.8mV

offset

+

VREF

20, 000

(20, 000 )

RX)

or

RX + 20, 000

VREF

DV

–1

VIN minimum (peak) input voltage must exceed this value to be detected (equivalent to adjusting V threshold)

VCC

Input

ÎÎ Va

2

Rx

20K

ÎÎÎÎ VREF 10

To Phase

Detector

Vb

20K

Figure 4. Desensitizing Input Stage

g) Calculate Data Filter Capacitance, CF:

Rsum

+

(RF ) R1)·RB

(R1 ) RF ) RB)

CF

+

0.25

(Rsum·Baud

Rate)

Baud

rate

in

1

seconds

Note: All values except R0 can be rounded to nearest standard value.

Rev. 3.01

11

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