si4021 Silicon Laboratories, si4021 Datasheet - Page 15

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

3. Frequency Setting Command
Note:
4. Data Rate Command
In EEPROM mode the transmitted bit rate is determined by the 8-bit value R (bits <r7 : r0>) as:
Apart from setting custom values, the standard bit rates from 2.4 to 115.2 kbps can be approximated with minimal error.
The commands are read out with a different fixed bit rate:
Note:
5. Power Setting Command
The bit ook enables the OOK mode for the PA, in this case the data to be transmitted are received through the FSK pin.
bit
bit
bit
•
•
The 12-bit parameter of the Frequency Setting Command <f11 :
f0> has the value F. The value F should be in the range of 96 and
3903. When F is out of range, the previous value is kept. The
synthesizer center frequency f
15
15
p2
1
1
7
1
For correct operation of the frequency synthesizer, the frequency and band of operation need to be programmed before the
synthesizer is started. Directly after activation of the synthesizer, the RF VCO is calibrated to ensure proper operation in the
programmed frequency band.
BR = 10 MHz / 29 / (R+1)
F
PLL bandwidth should be set according the data rate. Please see the PLL Setting Command.
0
0
0
0
1
1
1
1
sck
= 10 MHz / 29 / 3 [~115.2 kHz]
p1
14
14
0
1
6
0
0
0
1
1
0
0
1
1
f
0
= 10 MHz * C1 * (C2 + F/4000)
p0
0
1
0
1
0
1
0
1
13
13
1
0
5
1
Relative Output Pow er [dB]
12
12
0
0
4
1
ook
f11
11
11
1
3
0
can be calculated as:
f10
10
10
p2
-12
-15
-18
-21
0
2
-3
-6
-9
0
p1
f9
9
9
0
1
p0
f8
8
8
0
0
r7
f7
7
7
POR
B0h
r6
f6
6
6
The output power is given in the table as relative to the
maximum available power, which depends on the actual
antenna impedance. (See: Antenna Application Note
available from www.silabs.com/integration).
r5
f5
5
5
r4
f4
4
4
The constants C1 and C2 are determined by
the selected band as:
Band [MHz]
r3
f3
3
3
433
868
915
f2
r2
2
2
f1
r1
1
1
C1
1
2
3
f0
r0
0
0
C2
43
43
30
A7D0h
C800h
POR
POR
IA4221
15