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參數(shù)資料
| 型號(hào)： | MX805LH |
| 英文描述： | RF/Baseband Circuit |
| 中文描述： | 射頻/基帶電路 |
| 文件頁數(shù)： | 8/24頁 |
| 文件大?。?/td> | 532K |
| 代理商： | MX805LH |
Sub-Audio Signaling Processor
Recommended External Component Notes:
1. Xtal/Clock circuitry shown in inset are recommended in accordance with the MX-COM’s “Standard and
DBS 800 Crystal Oscillators” application note.
2. Resistor R8 is a System Component. Its value is chosen together with the MX806A Modulation Summing
Amplifier to provide a subaudio signal level of –11.0dB to the system modulator.
3. Figure 3 and Figure 4 illustrate alternative input component configurations.
4. The values for R2 and R5 are dependent on the input signal level. Values given are for the specified
composite signal (reference page 14). R4 add hysteresis to the comparator and is not always required.
5. The values used for C1 and C2 are determined by the frequency of X1.
5.0MHz
X1
for
p
33
2
C
1
C
>
=
=
If the on-chip Xtal oscillator is to be used, then the external components X1, C1, C2, and R1 are required
as shown in Figure 2 (inset). If an external clock source is used these components are not required; the
input should be connected to the Xtal/Clock pin and the
Xtal
pin unconnected.
Page 8 of 24
MX805A
2001 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
All trademarks and service marks are held by their respective companies.
Doc. # 20480116.005
As a guide:
5.0MHz
X1
for
18pF
C2
C1
<
=
=
6. Resistor R7 is used as the DBS800 system common pull-up for the C-BUS Interrupt Request (
IRQ
) line.
The optimum value of this component will depend upon the circuitry connected to the
IRQ
line.
7. The level at this point should be approximately 900mV
P-P.
8. Silicon small signal
3.1 Input Configurations
Figure 3 shows an input configuration that is generally for use for CTCSS signal and NRZ data reception.
Input coupling capacitor C3 is required because the RX Sub-Audio Input is held at V
BIAS
during all powered
conditions of the MX805A. Diodes D1 and D2 can be any silicon small signal diode.
The output resistance (open loop) of the on-chip Rx Amp is = 6k
. In the configuration shown in Figure 3, the
(Rx Amp) RC time constant is therefore 90ms. If this period is too long for some systems, i.e. those using half
duplex, short data burst, and external amplifier should be considered in place of the on-chip Rx Amp.
C4
C3
D1
R3
R5
R2
R4
D2
NOTE 7
+
+
_
_
MX805A
RX AMP
MX805A
RX LPF
RX SUB-AUDIO
INPUT
D.C. RESTORATION
MX805A
COMPARATOR
HYSTERESIS (OPTIONAL)
COMPARATOR
OUT
COMPARATOR IN
RX AMP IN
13
19
20
14
21
16
17
15
Figure 3: MX805A Input Components
3.1.1
For DC coupling the MX805A to the receiver’s discriminator output when using burst mode NRZ
communication, it is recommended that an additional, external Op-Amp is employed as configured in
Figure 4. This configuration will quickly compensate for sudden shift of DC input bas.
Components R9, R10, and R11, should be calculated to provide an accurate potential of 2.5VDC (equal to
V
BIAS
) at pin junction 15/16when using a discriminator input and 900mVP-P at the output of the external op-
amp. Note that the MX805A LPF has a 6dB gain. If additional filtering is required, C9 should be used, it
should be calculated with R9 to provide a lowpass cutoff frequency (f
CO
) of 500Hz.
Using and External Op-Amp
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PDF描述 |
|---|---|
| MX806ADW | Audio Processor |
| MX806ALH | Audio Processor |
| MX806J | Audio Processor |
| MX806LH | Audio Processor |
| MX809LH | MODEM |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MX806A | 制造商:CMLMICRO 制造商全稱:CML Microcircuits 功能描述:Audio Processor |
| MX806ADW | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Audio Processor |
| MX806AJ | 制造商:CMLMICRO 制造商全稱:CML Microcircuits 功能描述:Audio Processor |
| MX806ALH | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Audio Processor |
| MX806J | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Audio Processor |
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