si4021 Silicon Laboratories, si4021 Datasheet - Page 9

• Manufacturer Part Number: si4021
• Description: Si4021 Universal Ism Band Fsk Transmitter
• Manufacturer: Silicon Laboratories

Note 1:
for sending 100 byte packets in length at 19.2 kbps with +3 dBm output power in the 915 MHz band.
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Using a CR2032 battery (225 mAh capacity), the expected battery life is greater than 2 years using a 60-second wake-up period
Using anything but a 10 MHz crystal is allowed but not recommended because all crystal-referred timing and frequency
parameters will change accordingly.
Adjustable in 8 steps.
Optimal antenna admittance/impedance for the Si4021:
With selective resonant antennas (see: Application Notes available from http://www.silabs.com/integration).
During this period, no commands are accepted by the chip. For detailed information see the Reset modes section.
The maximum FSK bitrate and the Output phase noise are dependent on the on the actual setting of the PLL Setting Command.
The crystal oscillator start-up time strongly depends on the capacitance seen by the oscillator. Using low capacitance and low ESR
crystal is recommended. When designing the PCB layout keep the trace connecting to the crystal short to minimize stray
capacitance.
434 MHz
868 MHz
915 MHz
1.35E-3 - j1.2E-2
1.45E-3 - j1.3E-2
1.3E-3 - j6.3E-3
Yantenna [S]
Zantenna [Ohm]
31 + j152
8.7 + j77
9 + j82
Lantenna [nH]
58.00
15.20
13.60
IA4221
9