SM1211E915TOPIC Semtech, SM1211E915TOPIC Datasheet - Page 13

• Manufacturer Part Number: SM1211E915TOPIC
• Description: KIT PICTAIL EXT FOR SX1211
• Manufacturer: Semtech
• Type: Transceiver, UHFr

Specifications of SM1211E915TOPIC

• Frequency: 915MHz
• For Use With/related Products: SX1211
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

To ensure correct operation of the regulator circuit, the decoupling capacitor connection shown in Figure 4 is
required. These decoupling components are recommended for any design.
The frequency synthesizer of the SX1211 is a fully integrated integer-N type PLL. The PLL circuit requires only five
external components for the PLL loop filter and the VCO tank circuit.
The SX1211 embeds a crystal oscillator, which provides the reference frequency for the PLL. The recommended
crystal specification is given in section 7.1.
The reference frequency, or a sub-multiple of it, can be provided on CLKOUT (pin 19) by activating the bit
OSCParam_Clkout_on. The division ratio is programmed through bits OSCParam_Clkout_freq. The two
applications of the CLKOUT output are:
Note: To minimize the current consumption of the SX1211, ensure that the CLKOUT signal is disabled when
unused.
Rev 7 – Sept 2
ADVANCED COMMUNICATIONS & SENSING
3.2. Frequency Synthesis Description
To provide a clock output for a companion uC, thus saving the cost of an additional oscillator. CLKOUT can be
made available in any operation mode, except Sleep mode, and is automatically enabled at power-up.
To provide an oscillator reference output. Measurement of the CLKOUT signal enables simple software
trimming of the initial crystal tolerance.
3.2.1. Reference Oscillator
3.2.2. CLKOUT Output
nd
, 2008
Biasing :
-SPI
-Config. Registers
-POR
Vbat
Y5V
1ųF
Biasing analog
Reg_ana
blocks
1.0 V
Figure 4: Power Supply Breakdown
VR_1V
Pin 27
Y5V
1ųF
220nF
X7R
Page 13 of 92
Biasing digital
Reg_top
blocks
Reg_dig
1.4 V
1.0 V
VR_DIG
External Supply
Pin 28
VDD – Pin 26
2.1 – 3.6V
100nF
X7R
Biasing :
-VCO circuit
-Ext. VCO
tank
Reg_VCO
0.85 V
VR_VCO
Pin 3
47nF
Biasing :
-PA Driver
-PA choke
(ext)
X7R
Reg_PA
1.80 V
VR_PA
Pin 29
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SX1211