Os motores de busca de Datasheet de Componentes eletrônicos |
|
SI4420 Folha de dados(PDF) 3 Page - Silicon Laboratories |
|
SI4420 Folha de dados(HTML) 3 Page - Silicon Laboratories |
3 / 33 page Si4420 3 Data Validity Blocks RSSI A digital RSSI output is provided to monitor the input signal level. It goes high if the received signal strength exceeds a given preprogrammed level. An analog RSSI signal is also available. The RSSI settling time depends on the external filter capacitor. Pin 15 is used as analog RSSI output. The digital RSSI can be can be monitored by reading the status register. Analog RSSI Voltage vs. RF Input Power Input Power [dBm] RSSI voltage [V] P4 P2 P1 P3 P1 -65 dBm 1300 mV P2 -65 dBm 1000 mV P3 -100 dBm 600 mV P4 -100 dBm 300 mV DQD The Data Quality Detector is based on counting the spikes on the unfiltered received data. For correct operation, the “DQD threshold” parameter must be filled in by using the Data Filter Command. AFC By using an integrated Automatic Frequency Control (AFC) feature, the receiver can minimize the TX/RX offset in discrete steps, allowing the use of: Inexpensive, low accuracy crystals Narrower receiver bandwidth (i.e. increased sensitivity) Higher data rate Crystal Oscillator The Si4420 has a single-pin crystal oscillator circuit, which provides a 10 MHz reference signal for the PLL. To reduce external parts and simplify design, the crystal load capacitor is internal and programmable. Guidelines for selecting the appropriate crystal can be found later in this datasheet. The transceiver can supply the clock signal for the microcontroller; so accurate timing is possible without the need for a second crystal. When the microcontroller turns the crystal oscillator off by clearing the appropriate bit using the Configuration Setting Command, the chip provides a fixed number (196) of further clock pulses (“clock tail”) for the microcontroller to let it go to idle or sleep mode. Low Battery Voltage Detector The low battery detector circuit monitors the supply voltage and generates an interrupt if it falls below a programmable threshold level. The detector circuit has 50 mV hysteresis. Wake-Up Timer The wake-up timer has very low current consumption (1.5 μA typical) and can be programmed from 1 ms to several days with an accuracy of ±5%. It calibrates itself to the crystal oscillator at every startup. When the crystal oscillator is switched off, the calibration circuit switches it on only long enough for a quick calibration (a few milliseconds) to facilitate accurate wake-up timing. Event Handling In order to minimize current consumption, the transceiver supports different power saving modes. Active mode can be initiated by several wake-up events (negative logical pulse on nINT input, wake-up timer timeout, low supply voltage detection, on-chip FIFO filled up or receiving a request through the serial interface). If any wake-up event occurs, the wake-up logic generates an interrupt signal, which can be used to wake up the microcontroller, effectively reducing the period the microcontroller has to be active. The source of the interrupt can be read out from the transceiver by the microcontroller through the SDO pin. Interface and Controller An SPI compatible serial interface lets the user select the frequency band, center frequency of the synthesizer, and the bandwidth of the baseband signal path. Division ratio for the microcontroller clock, wake-up timer period, and low supply voltage detector threshold are also programmable. Any of these auxiliary functions can be disabled when not needed. All parameters are set to default after power-on; the programmed values are retained during sleep mode. The interface supports the read-out of a status register, providing detailed information about the status of the transceiver and the received data. The transmitter block is equipped with an 8 bit wide TX data register. It is possible to write 8 bits into the register in burst mode and the internal bit rate generator transmits the bits out with the predefined rate. It is also possible to store the received data bits into a FIFO register and read them out in a buffered mode. |
Nº de peça semelhante - SI4420 |
|
Descrição semelhante - SI4420 |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |