SX1212IWLTRT Semtech, SX1212IWLTRT Datasheet - Page 20

• Manufacturer Part Number: SX1212IWLTRT
• Description: IC TXRX 300MHZ-510MHZ 32-TQFN
• Manufacturer: Semtech

Specifications of SX1212IWLTRT

• Frequency: 300MHz ~ 510MHz
• Data Rate - Maximum: 150kbps
• Modulation Or Protocol: FSK, OOK
• Applications: AMR, ISM, Home Automation, Process Control
• Power - Output: 12.5dBm
• Sensitivity: -110dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 3mA
• Current - Transmitting: 25mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFN
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Modulation Type: FSK/OOK
• Package Type: TQFN EP
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (typ): 2.5/3.3V
• Operating Supply Voltage (max): 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed
• Other names: SX1212IWLTR

After digital to analog conversion, both I and Q signals are smoothed by interpolation filters. This block low-pass
filters the digitally generated signal, and prevents the alias signals from entering the modulators. Its bandwidth can
be programmed with the register RXParam_InterpFiltTx, and should be set to:
Where Fdev is the programmed frequency deviation as set in MCParam_Freq_dev, and BR is the physical Bit Rate
of transmission.
Notes:
The Power Amplifier (PA) integrated in the SX1212 operates under a regulated voltage supply of 1.8 V. The
external PA choke inductor is biased by an internal regulator output made available on pin 29 (VR_PA). Thanks to
these features, the PA output power is consistent over the power supply range. This is important for mobile
applications where this allows both predictable RF performance and battery life.
In OOK mode, the PA ramp times can be accurately controlled through the MCParam_PA_ramp register. Those
bits directly control the slew rate of VR_PA output (pin 29).
Table 11: PA Rise/Fall Times
MCParam_PA_ramp
Rev 2 – June 18th, 2009
ADVANCED COMMUNICATIONS & SENSING
Low interpolation filter bandwidth will attenuate the baseband I/Q signals thus reducing the power of the FSK
signal. Conversely, excessive bandwidth will degrade spectral purity.
For the wideband FSK modulation, for example when operating in DTS mode, the recommended filter setting
can not be reached. However, the impact upon spectral purity will be negligible, due to the already wideband
channel.
00
01
10
11
3.3.6. Interpolation Filter
3.3.7. Power Amplifier
3.3.7.1. Rise and Fall Times Control
t
3 us
8.5 us
15 us
23 us
VR_PA
t
2.5 / 2 us
5 / 3 us
10 / 6 us
20 / 10 us
PA_OUT
(rise / fall)
BW
≅
3
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⎢
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Fdev
+
BR
2
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