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| 型号： | MICRF007BM |
| 厂商： | Micrel Inc |
| 文件页数： | 7/13页 |
| 文件大小： | 0K |
| 描述： | IC RECEIVER UHF LOW POWER 8SOIC |
| 标准包装： | 95 |
| 频率： | 300MHz ~ 440MHz |
| 灵敏度： | -96dBm |
| 数据传输率 - 最大： | 2.1 kbps |
| 调制或协议： | ASK，OOK |
| 应用： | RKE |
| 电流 - 接收： | 3mA |
| 数据接口： | PCB，表面贴装 |
| 天线连接器： | PCB，表面贴装 |
| 特点： | 自动调谐 |
| 电源电压： | 4.75 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
f LO = f TX ± ? 1.18
? f TX ?
(1)
?
433.92 ?
f T =
RSC = 110kΩ
C TH =
C AGC =
MICRF007
appropriate f LO for a given f TX :
?
Frequencies f TX and f LO are in MHz. Note that two values
of f LO exist for any given f TX , distinguished as “high-side
mixing” and “low-side mixing.” High-side mixing results in an
image frequency above the frequency of interest and low-
side mixing results in a frequency below. There is generally
no preference of one over the other.
After choosing one of the two acceptable values of f LO , use
Equation 2 to compute the reference oscillator frequency
f T :
f LO
64.5 (2)
Frequency f T is in MHz. Connect a crystal of frequency f T to
REFOSC on the MICRF007. Four-decimal-place accuracy
on the frequency is generally adequate. The following table
identi?es f T for some common transmit frequencies.
Transmit Reference
Frequency f TX Oscillator Frequency f T
315MHz 4.8970MHz
390MHz 6.0630MHz
418MHz 6.4983MHz
433.92MHz 6.7458MHz
Table 2. Recommended Reference Oscillator Values
for Typical Transmit Frequencies (high-side mixing)
Step 2: Selecting C TH Capacitor
Extraction of the DC value of the demodulated signal for
purposes of logic-level data slicing is accomplished using the
external threshold capacitor C TH and the on-chip switched
capacitor “resistor” RSC, shown in the block diagram.
Slicing level time constant values vary somewhat with de-
coder type, data pattern, and data rate, but typically values
range from 5ms to 50ms.This issue is covered in more detail
in “Application Note 22.” Optimization of the value of C TH is
required to maximize range.
τ of 5x the bit-rate is recommended. The effective resistance
of RSC is listed in the electrical characteristics table as 110kΩ
at 433.92MHz, This value scales inversely with frequency.
Source impedance of the C TH pin at other frequencies is
given by equation (3), where f T is in MHz:
6.7458
f T (3)
Since slicing level time constant τ has been established
as 5 times bit rate, capacitor C TH may be computed using
equation (4),
?
R SC (4)
A standard ±20% X7R ceramic capacitor is generally suf?-
cient. Refer to “Application Hint 42” for C TH and C AGC selec-
tion examples.
Micrel
Step 3: Selecting C AGC Capacitor
The signal path has automatic gain control (AGC) to increase
input dynamic range. The attack time constant of the AGC is
set externally by the value of the C AGC capacitor connected
to the C AGC pin of the device. To maximize system range,
it is important to keep the AGC control voltage ripple low,
preferably under 10mV PP once the control voltage has at-
tained its quiescent value. For this reason, capacitor values
of at least 0.47μF are recommended.
The AGC control voltage is carefully managed on-chip to al-
low duty-cycle operation of the MICRF007. When the device
is placed into shutdown mode (SHUT pin is pulled high), the
AGC capacitor ?oats to retain the voltage. When operation
is resumed, only the voltage droop due to capacitor leakage
must be replenished. A relatively low-leakage capacitor is
recommended when the devices are used in duty-cycled
operation.
To further enhance duty-cycled operation, the AGC push
and pull currents are boosted for approximately 10ms im-
mediately after the device is taken out of shutdown. This
compensates for AGC capacitor voltage droop and reduces
the time to restore the correct AGC voltage. The current is
boosted by a factor of 45.
Selecting C AGC Capacitor in Continuous Mode
A C AGC capacitor in the range of 0.47μF to 4.7μF is typically
recommended. Caution! If the capacitor is too large, the
AGC may react too slowly to incoming signals. AGC set-
tling time from a completely discharged (zero-volt) state
is given approximately by this equation:
? t = 1.333 × C AGC –0.44 (5)
where:
C AGC is in μF, and ? t is in seconds.
Selecting C AGC Capacitor in Duty-Cycle Mode
Voltage droop across the C AGC capacitor during shutdown
should be replenished as quickly as possible after the IC is
enabled. As mentioned above, the MICRF007 boosts the
push-pull current by a factor of 45 immediately after start-up.
This ?xed time period is based on the reference oscillator
frequency f T . The time is 10.9ms for f T = 6.00MHz, and varies
inversely with f T . The value of C AGC capacitor and the duration
of the shutdown time period should be selected such that the
droop can be replenished within this 10ms period.
Polarity of the droop is unknown, meaning the AGC voltage
could droop up or down. The worst-case from a recovery
standpoint is downward droop, since the AGC pull-up current
is 1/10th magnitude of the pull-down current. The downward
droop is replenished according to the Equation 6:
I ? t
? V (6)
where:
I = AGC pull-up current for the initial 10ms (67.5μA)
CAGC = AGC capacitor value
? t = droop recovery time
February 17, 2005
7
M9999-021705
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MICRF007BM TR | 功能描述:IC RECEIVER UHF 300MHZ 8-SOIC RoHS:否 类别:RF/IF 和 RFID >> RF 接收器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS 产品变化通告:Product Discontinuation 09/Jan/2012 标准包装:50 系列:* 频率:850MHz ~ 2.175GHz 灵敏度:- 数据传输率 - 最大:- 调制或协议:- 应用:* 电流 - 接收:* 数据接口:PCB，表面贴装 存储容量:- 天线连接器:PCB，表面贴装 特点:- 电源电压:4.75 V ~ 5.25 V 工作温度:0°C ~ 85°C 封装/外壳:40-WFQFN 裸露焊盘 供应商设备封装:40-TQFN-EP（6x6） 包装:托盘 |
| MICRF007YM | 功能描述:射频接收器 300-440MHz Receiver, 1.2kbps, 1.7mA With Shutdown( Lead Free) RoHS:否 制造商:Skyworks Solutions, Inc. 类型:GPS Receiver 封装 / 箱体:QFN-24 工作频率:4.092 MHz 工作电源电压:3.3 V 封装:Reel |
| MICRF007YM TR | 功能描述:射频接收器 300-440MHz Receiver, 1.2kbps, 1.7mA With Shutdown( Lead Free) RoHS:否 制造商:Skyworks Solutions, Inc. 类型:GPS Receiver 封装 / 箱体:QFN-24 工作频率:4.092 MHz 工作电源电压:3.3 V 封装:Reel |
| MICRF008 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:QwikRadio Sweep-Mode Receiver |
| MICRF008_11 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:QwikRadio Sweep-Mode Receiver |
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