MICRF221 データシートの表示（PDF） - Micrel

部品番号

コンポーネント説明

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MICRF221

3.3V, QwikRadio® 850 MHz to 950 MHz Receiver

Micrel 

Micrel Inc.

Electrical Characteristics (continued)

RSSI

Symbol

Parameter

Condition

RSSI DC Output Voltage

Range

RSSI response slope

-109 dBm to -40 dBm

RSSI Output Impedance

MICRF221

Min

Typ

Max Units

0.2 to 2.0

V

26

mV/dB

220

Ω

Notes:

1.

2.

3.

4.

5.

6.

7.

8.

Exceeding the absolute maximum rating may damage the device.

The device is not guaranteed to function outside its operating rating.

Device is ESD sensitive. Use appropriate ESD precautions. Exceeding the absolute maximum rating may damage the device.

Sensitivity is defined as the average signal level measured at the input necessary to achieve 10-2 BER (bit error rate). The input signal is

defined as a return-to-zero (RZ) waveform with 50% average duty cycle (Manchester encoded).

Spurious reverse isolation represents the spurious component which appears on the RF input pin (ANT), measured into 50Ohms with an

input RF matching network.

When data burst does not contain preamble, duty cycle is defined as total duty cycle, including any “quiet” time between data bursts. When

data bursts contain preamble sufficient to charge the slice level on capacitor CTH, then duty cycle is the effective duty cycle of the burst

alone. [For example, 100msec burst with 50% duty cycle, and 100msec “quiet” time between bursts). If burst includes preamble, duty

cycle isTON/(TON + TOFF)= 50%; without preamble, duty cycle is TON/(TON + TOFF + TQUIET) = 50msec/200msec = 25%. TON is the number of 1’s

during the burst time × bit time TOFF = TBURST – TON.

Auto-polling refers to power-cycling mode of operation where characteristics of the received signal are used to determine the likelihood of

an incoming data signal at the beginning of the Ton period. If there is no signal detected within a period programmable by the user, the

user can program the number of bits: 0,2,4,8 that must be good for device to wake up. The time will depend on the data rate. If two bad

bits are detected this will cause device to revert to SLEEP. If no bits are detected device will revert to SLEEP in 5ms, 10ms, or 20ms

depending on selected demodulator bandwidth. Otherwise, the device remains “On” until commanded into SLEEP by an external source

e.g., decoder or microprocessor. This technique minimizes the average Ton time. Refer to Serial Interface and Applications sub-sections

for further details.

Average SLEEP mode current depends on the SLEEP time programmed and the SLEEP oscillator variation which is ~+/-20% independent

of ref osc.

October 2008

5

M9999-100108

(408) 955-1690

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