4421-DKDB1 Silicon Laboratories Inc, 4421-DKDB1 Datasheet - Page 16

• Manufacturer Part Number: 4421-DKDB1
• Description: KIT DEV TEST EZRADIO SI4421 TRX
• Manufacturer: Silicon Laboratories Inc

Specifications of 4421-DKDB1

• Accessory Type: Test Card, Transceiver, 915MHz
• Wireless Frequency: 915 MHz
• Interface Type: SPI
• Modulation: FSK
• For Use With/related Products: EZRadio®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

Logic connections between power control bits:
Note:
Clock tail feature: When the clock output (pin 8) used to provide clock signal for the microcontroller (dc bit is set to 0), it is possible
to use the clock tail feature. This means that the crystal oscillator turn off is delayed, after issuing the command (clearing the ex bit)
192 more clock pulses are provided. This ensures that the microcontroller can switch itself to low power consumption mode. In order
to use this feature, a Status Read Command (page 27) must be issued before the ex bit set to zero. If status read was not performed
then the clock output shuts down immediately leaving the microcontroller in unknown state.
Automatic crystal oscillator enable/disable feature: When an interrupt occurs, the crystal oscillator automatically turns on –
regardless to the setting of the ex bit – to supply clock signal to the microcontroller. After clearing all interrupts by handling them
properly (see the Interrupt Handling section, page 28) and performing Status Read Command, the crystal oscillator is automatically
turned off. The clock tail feature provides enough clock pulses for the microcontroller to go to low power mode. Due to this automatic
feature, it is not possible to turn off the crystal by clearing the ex bit if any interrupt is active. For example, after power on the POR
interrupt must be cleared by a status read then writing zero to the ex bit will put the part into sleep mode. Very important to clear all
interrupts before turning the ex bit off because the extra current required by running crystal oscillator can shorten the battery life
significantly.
Disabling the clock output (bit dc=1) turns off both the clock tail and the automatic crystal oscillator enable/disable feature, only the
ex bit controls the crystal oscillator (supposing that both the er and et bits are cleared), the interrupts have no effect on it.
 If both et and er bits are set the chip goes to receive mode.
 FSK / nFFS input are equipped with internal pull-up resistor. To achieve minimum current consumption do not pull this input
 To enable the RF synthesizer, the crystal oscillator must be turned on
 To turn on the baseband circuits, the RF synthesizer (and this way the crystal oscillator) must be enabled.
 Setting the er bit automatically turns on the crystal oscillator, the synthesizer, the baseband circuits and the RF fronted.
 Setting the et bit automatically turns on the crystal oscillator, the synthesizer and the RF power amplifier.
to logic low in sleep mode.
ebb
es
ex
et
er
Edge
detector
enable baseband
power amplifier
RF synthesizer
clear TX latch
enable crystal
RF front end
oscillator
enable
start TX
circuits
enable
enable
power amplifier
crystal oscillator
RF synthesizer
clear TX latch
enable
start TX
enable
enable
VCO and
oscillator
TX latch
Crystal
PLL
clock and data out
Digital signal
processing
demod
I/Q
enable baseband
RF front end
enable
circuits
Si4421
16