MICRF221_15 Datasheet, PDF (5/26 Pages) Micrel Semiconductor – 3.3V, QwikRadio® 850 MHz to 950 MHz Receiver

Micrel Inc.
MICRF221
Electrical Characteristics (Continued)
RSSI
Symbol
Parameter
Condition
RSSI DC Output Voltage
Range
RSSI Response Slope
-109dBm to -40dBm
RSSI Output Impedance
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 50Ω 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) = 50ms/200ms = 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.
August 12, 2015
5
Revision 2.0