SX1212IWLTRT Semtech, SX1212IWLTRT Datasheet - Page 15

• 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

With the recommended Bill Of Materials (BOM) of the reference design of section 7.5.3, the PLL prototype is the
following:
The integrated VCO requires only two external tank circuit inductors. As the input is differential, the two inductors
should have the same nominal value. The performance of these components is important for both the phase noise
and the power consumption of the PLL. It is recommended that a pair of high Q factor inductors is selected. These
should be mounted orthogonally to other inductors (in particular the PA choke) to reduce spurious coupling
between the PA and VCO. In addition, such measures may reduce radiated pulling effects and undesirable
transient behavior, thus minimizing spectral occupancy. Note that ensuring a symmetrical layout of the VCO
inductors will further improve PLL spectral purity.
For best performance wound type inductors, with tight tolerance, should be used as described in section 7.5.3.
To guarantee the optimum operation of the VCO over the SX1212’s frequency and temperature ranges, the
following settings should be programmed into the SX1212:
Table 10: MCParam_Freq_band Setting
To ensure that the frequency band of operation may be accurately addressed by the R, P and S dividers of the
synthesizer, it is necessary to ensure that the VCO is correctly centered. Note that for the reference design (see
section 7.5) no centering is necessary. However, any deviation from the reference design may require the
optimization procedure, outlined below, to be implemented. This procedure is simplified thanks to the built-in VCO
trimming feature which is controlled over the SPI interface. This tuning does not require any RF test equipment,
and can be achieved by simply measuring Vtune, the voltage between pins 6 (LFM) and 7 (LFP).
The VCO is centered if the voltage is within the range:
Note that this measurement should be conducted when in transmit mode at the center frequency of the desired
band (for example ~315 MHz in the 300-330 MHz band), with the appropriate MCParam_Freq_band setting.
If this inequality is not satisfied then adjust the MCParam_VCO_trim bits from 00 whilst monitoring Vtune. This
allows the VCO voltage to be trimmed in + 60 mV increments. Should the desired voltage range be inaccessible,
the voltage may be adjusted further by changing the tank circuit inductance value. Note that an increase in
inductance will result in an increase Vtune.
Rev 2 – June 18th, 2009
ADVANCED COMMUNICATIONS & SENSING
Target channel
Freq_band
64 ≤ R ≤ 169
S < P+1
PLLBW = 15 kHz nominal
Startup times and reference frequency spurs as specified.
(MHz)
3.2.5. Voltage Controlled Oscillator
3.2.5.1. SW Settings of the VCO
3.2.5.2. Trimming the VCO Tank by Hardware and Software
300-
330
000
320-
350
001
350-
390
010
390-
100
430
011
≤
Vtune
Page 15 of 77
430-
470
100
(
mV
470-
510
101
)
≤
200
www.semtech.com
SX1212