參數(shù)資料
型號： MICRF008
廠商： Micrel Semiconductor,Inc.
英文描述： QwikRadio⑩ Sweep-Mode Receiver
中文描述： QwikRadio系列⑩掃描模式接收機
文件頁數(shù)： 10/12頁
文件大?。?/td> 115K
代理商： MICRF008
MICRF008
Micrel
MICRF008
10
July 2003
C
TH
Capacitor
In order to calculate the right value for the C
TH
capacitor, the
data format needs to have a preamble that resembles the
data pattern, that is it has the same period and duty cycle.
(See
“
Application Hint 42
”
. ) If the data pattern has no
preamble, a large capacitor value should be used, such as
1
μ
F to 2.2
μ
F. However, if the data pattern has a preamble,
the C
TH
capacitor can be calculated and should be used
instead of a large capacitor. This will guarantee a stable and
reliable performance for the receiver. If the data pattern has
variable data rates, the C
TH
capacitor should be calculated
for the lowest data rate and optimized in range tests. To find
the C
TH
capacitor value follow the procedure below:
1. Find the data period or bit period, and the
reference oscillator frequency. The reference
oscillator frequency is the RF carrier frequency
divided by 129. The bit period is the elapsed
time from one high and one low of the data
pattern.
2. The C
TH
capacitor is calculated by:
=5
144.55 10
where:
REFOSC is the reference oscillator frequency in
MHz.
Bit period is given in seconds and is the inverse
of the baud rate for Manchester encoding.
The result obtained is in farads.
It follows the C
TH
capacitor value for the common frequencies
mentioned above in the Table 4. Again, as mentioned before,
the data pattern needs preamble.
C
bit period REFOSC
F
[ ]
TH
3
×
Baud Rate (Hz)
2400
C
TH
39nF
47nF
47nF
47nF
1000
C
TH
82nF
100nF
120nF
120nF
4800
C
TH
18nF
22nF
22nF
22nF
Frequency (MHz)
315
390
418
433.92
Table 4. Recommended C
TH
Capacitor Values
C
AGC
Capacitor
The function of the C
AGC
capacitor is to minimize the ripple on
the AGC control voltage by using a sufficiently large capaci-
tor. It is suggested a value between 1
μ
F to 10
μ
F depending
on data dead time, noise, and recovery time from strong to
low RF signals. Large capacitor values can be connected to
V
DD
if fast charge time is required (C2). When connected to
V
DD
, it will charge 10 times faster. The drawback is the ripple
noise from AGC pin being thrown into the V
DD
line. The signal
on this pin is current-based, with an attack current of 15
μ
A,
and a decay current of 1.5
μ
A. It is suggested the following
values for the C
AGC
capacitors in the Table 5. Values can be
further optimized during receiver range tests.
Baud Rate (Hz)
1000
2400
4800
Table 5. Recommended Values for C
AGC
Reference Oscillator Frequency
A Colpitts oscillator inside the chip generates the reference
oscillator frequency. It requires a resonator of some kind
connected to the REFOSC pin. Either a ceramic resonator or
a crystal can be used. A resonator is chosen due to its lower
cost and because the MICRF008BM is running in sweep
mode, which does not require the precision of a crystal.
Resonators found in the market normally have a precision of
0.5%. This precision is sufficient for the MICRF008BM. The
reference oscillator frequency can also be generated by an
external source through connector J1 and capacitor C1. The
maximum level should not exceed 0.5V
RMS
. The reference
oscillator frequency is calculated by the following equation
and Table 6 shows the resonator frequency for the most
common used frequencies:
C
AGC
(
μ
F)
4.7 to 10
2.2 to 4.7
1 to 2.2
REFOSC=
fc
129
where:
REFOSC is the reference oscillator frequency in
MHz.
fc is the RF received carrier frequency of interest
in MHz.
Freq. (MHz)
315.0
390.0
418.0
433.92
Table 6. Reference Oscillator Frequency
REFOSC (MHz)
2.44
3.02
3.24
3.36
For a list of ceramic resonator manufactures, see
“
Applica-
tion Hint 35.
”
SEL0 Pin
–
Setting the Demodulator Bandwidth
The SEL0 pin sets the demodulator bandwidth. When the pin
is connected to ground the demodulator bandwidth is set to
its minimum. When the pin is left floating (internal pull-up) or
connected to V
DD
, the demodulator bandwidth is set to its
maximum. The demodulator bandwidth is a function of the RF
frequency used. See Table 7 for the most common frequency
used versus the demodulator bandwidth.
RF Carrier Frequency (MHz)
390
2.0kHz
4.0kHz
Table 7. Demodulator Bandwidth
SEL0
0
1
315
1.6kHz
3.6kHz
418
2.2kHz
4.4kHz
433.92
2.4kHz
4.8kHz
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MICRF008_11 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:QwikRadio Sweep-Mode Receiver
MICRF008BM 功能描述:IC RECEIVER 300-440MHZ 8-SOIC RoHS:否 類別:RF/IF 和 RFID >> RF 接收器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS 產(chǎn)品變化通告:Product Discontinuation 09/Jan/2012 標準包裝:50 系列:* 頻率:850MHz ~ 2.175GHz 靈敏度:- 數(shù)據(jù)傳輸率 - 最大:- 調(diào)制或協(xié)議:- 應(yīng)用:* 電流 - 接收:* 數(shù)據(jù)接口:PCB，表面貼裝 存儲容量:- 天線連接器:PCB，表面貼裝 特點:- 電源電壓:4.75 V ~ 5.25 V 工作溫度:0°C ~ 85°C 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（6x6） 包裝:托盤
MICRF008BM TR 功能描述:IC RECEIVER 300-440MHZ 8-SOIC RoHS:否 類別:RF/IF 和 RFID >> RF 接收器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS 產(chǎn)品變化通告:Product Discontinuation 09/Jan/2012 標準包裝:50 系列:* 頻率:850MHz ~ 2.175GHz 靈敏度:- 數(shù)據(jù)傳輸率 - 最大:- 調(diào)制或協(xié)議:- 應(yīng)用:* 電流 - 接收:* 數(shù)據(jù)接口:PCB，表面貼裝 存儲容量:- 天線連接器:PCB，表面貼裝 特點:- 電源電壓:4.75 V ~ 5.25 V 工作溫度:0°C ~ 85°C 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（6x6） 包裝:托盤
MICRF008YM 功能描述:射頻接收器 300-440MHz Low-Cost Receiver, Sweep-Mode( Lead Free) RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel
MICRF008YM TR 功能描述:射頻接收器 300-440MHz Low-Cost Receiver, Sweep-Mode( Lead Free) RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel
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