SX1231-31SKB915 Semtech, SX1231-31SKB915 Datasheet - Page 23

• Manufacturer Part Number: SX1231-31SKB915
• Description: TVS
• Manufacturer: Semtech

Specifications of SX1231-31SKB915

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.5.3. Automatic Gain Control
By default (LnaGainSelect = 000), the LNA gain is controlled by a digital AGC loop in order to obtain the optimal sensitivity/
linearity trade-off.
Regardless of the data transfer mode (Packet or Continuous), the following series of events takes place when the receiver
is enabled:
Notes - the AGC procedure must be performed while receiving preamble in FSK mode
The following figure illustrates the AGC behavior:
The following table summarizes the performance (typical figures) of the complete receiver:
Rev 3 - April 2010
ADVANCED COMMUNICATIONS & SENSING
The receiver stays in WAIT mode, until RssiValue exceeds RssiThreshold for two consecutive samples. Its power
consumption is the receiver power consumption.
When this condition is satisfied, the receiver automatically selects the most suitable LNA gain, optimizing the sensitivity/
linearity trade-off.
The programmed LNA gain, read-accessible with LnaCurrentGain in RegLna, is carried on for the whole duration of the
packet, until one of the following conditions is fulfilled:
Packet mode: if AutoRxRestartOn = 0, the LNA gain will remain the same for the reception of the following packet. If
AutoRxRestartOn = 1, after the controller has emptied the FIFO the receiver will re-enter the WAIT mode described
above, after a delay of InterPacketRxDelay, allowing for the distant transmitter to ramp down, hence avoiding a false
RSSI detection.
Continuous mode: upon reception of valid data, the user can decide to either leave the receiver enabled with the same
LNA gain, or to restart the procedure, by setting RestartRx bit to 1, resuming the WAIT mode of the receiver, described
above.
-125 dBm
Towards
- in OOK mode, the AGC will give better results if performed while receiving a constant “1” sequence
Lower Noise Figure
Higher Sensitivity
G1
Lower Linearity
16dB
Figure 7. AGC Thresholds Settings
G2
7dB
Page 23
G3
11dB
G4
9dB
11dB
G5
Higher Noise Figure
Lower Sensitivity
Higher Linearity
DATASHEET
G6
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SX1231
Pin [dBm]