SI4313-B1-FM Silicon Laboratories Inc, SI4313-B1-FM Datasheet - Page 39

• Manufacturer Part Number: SI4313-B1-FM
• Description: IC RX FSK 315-915MHZ 20VQFN
• Manufacturer: Silicon Laboratories Inc
• Series: EZRadio®r
• Type: ISM Receiverr

Specifications of SI4313-B1-FM

• Package / Case: 20-VQFN
• Mfg Application Notes: Si4313 Register Desc AppNote
• Frequency: 315MHz, 434MHz, 868MHz, 915MHz
• Sensitivity: -118dBm
• Data Rate - Maximum: 128kbps
• Modulation Or Protocol: FSK, GFSK, OOK
• Applications: Data Logging, Health Monitors, Remote Control, Weather Station
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 1.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Operating Frequency: 315 MHz to 915 MHz
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Supply Current: 100 nA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Memory Size: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1980-5

8.6. RSSI and Clear Channel Assessment
Received signal strength indicator (RSSI) is an estimate of the signal strength in the channel to which the receiver
is tuned. The RSSI value can be read from an 8-bit register with 0.5 dB resolution per bit. Figure 12 demonstrates
the relationship between input power level and RSSI value. The absolute value of the RSSI will change slightly
depending on the modem settings. The RSSI may be read at anytime, but an incorrect error may rarely occur. The
RSSI value may be incorrect if read during the update period. The update period is approximately 10 ns every
4 Tb. For 10 kbps, this would result in a 1 in 40,000 probability that the RSSI may be read incorrectly. This
probability is extremely low, but to avoid this, one of the following options is recommended: majority polling,
reading the RSSI value within 1 Tb of the RSSI interrupt, or using the RSSI threshold described in the next
paragraph for Clear Channel Assessment (CCA).
For CCA, threshold is programmed into rssith[7:0] in "Register 27h. RSSI Threshold for Clear Channel Indicator."
After the RSSI is evaluated in the preamble, a decision is made if the signal strength on this channel is above or
below the threshold. If the signal strength is above the programmed threshold then the RSSI status bit, irssi, in
"Register 04h. Interrupt/Status 2" will be set to 1. The RSSI status can also be routed to a GPIO line by configuring
the GPIO configuration register to GPIOx[3:0] = 1110.
Add R/W
26
27
R/W
R
250
200
150
100
50
RSSI Threshold for Clear Channel Indicator
0
-120
Received Signal Strength Indicator
Function/Description
-100
Figure 12. RSSI Value vs. Input Power
-80
rssith[7]
RSSI vs Input Power
rssi[7]
D7
-60
rssith[6]
Rev. 1.0
rssi[6]
In Pow [dBm]
D6
rssith[5]
rssi[5]
D5
-40
rssith[4]
rssi[4]
D4
rssith[3]
rssi[3]
D3
-20
rssith[2]
rssi[2]
D2
rssith[1]
rssi[1]
0
Si4313-B1
D1
rssith[0]
rssi[0]
D0
20
POR Def.
00h
—
39