AX5151-TSSOP24-TU AXSEM, AX5151-TSSOP24-TU Datasheet - Page 27

• Manufacturer Part Number: AX5151-TSSOP24-TU
• Description: RF Transmitter TSSOP-Class-IC
• Manufacturer: AXSEM
• Type: Single Chip Transceiverr

Specifications of AX5151-TSSOP24-TU

• Package / Case: TSSOP-24
• Operating Frequency: 400 MHz to 940 MHz
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 2.3 V to 3.6 V
• Supply Current: 100 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

802.15.4 (ZigBee)
802.15.4 uses binary phase shift keying (PSK) with 300 kbit/s (868 MHz band) or 600 kbit/s (915
MHz band) on the radio. The usable bit rate is only a 15
spreading function in the transmitter expands the user bit rate by a factor of 15, to make the
transmission more robust. The despreader function of the receiver undoes that.
In 802.15.4 mode, the AX5151 framing unit performs the spreading and despreading function
according to the 802.15.4 specification. In receive mode, the framing unit will also
automatically search for the 802.15.4 preamble, meaning that no interrupts will have to be
serviced by the micro-controller until a packet start is detected.
5.11. RX AGC and RSSI
AX5151 features two receiver signal strength indicators (RSSI):
Version 1.0
1. RSSI before the digital IF channel filter.
2. RSSI behind the digital IF channel filter.
The gain of the receiver is adjusted in order to keep the analog IF filter output level
inside the working range of the ADC and demodulator. The register AGCCOUNTER
contains the current value of the AGC and can be used as an RSSI. The step size of
this RSSI is 0.625 dB. The value can be used as soon as the RF frequency generation
sub-system has been programmed.
The demodulator also provides amplitude information in the TRK_AMPLITUDE register.
By combining both the AGCCOUNTER and the TRK_AMPLITUDE registers, a high
resolution (better than 0.1dB) RSSI value can be computed at the expense of a few
arithmetic operations on the micro-controller. Formulas for this computation can be
found in the AX5151 Programming Manual.
th
of the radio bit rate, however. A
Circuit Description
Datasheet AX5151
27