SI4020 查看數據表（PDF） - Silicon Laboratories
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SI4020 Datasheet PDF : 32 Pages
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Si4020
3. Frequency Setting Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 0 1 0 f11 f10 f9 f8 f7 f6 f5 f4 f3 f2 f1 f0
POR
A7D0h
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 can be calculated as:
0
f = 10 MHz * C1 * (C2 + F/4000)
0
Note:
The constants C1 and C2 are determined by
the selected band as:
Band [MHz]
315
433
868
915
C1 C2
1 31
1 43
2 43
3 30
• 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.
• When coding for the Si4020, it is suggested that recalibration routines be added to compensate for significant changes in
temperature and supply voltages.
4. Data Rate Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 0 1 0 0 0 r7 r6 r5 r4 r3 r2 r1 r0
POR
C800h
In EEPROM mode the transmitted bit rate is determined by the 8-bit value R (bits <r7 : r0>) as:
BR = 10 MHz / 29 / (R+1)
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:
Fsck = 10 MHz / 29 / 3 [~115.2 kHz]
5. Power Setting Command
bit 7 6 5 4 3 2 1 0
1 0 1 1 ook p2 p1 p0
POR
B0h
The bit ook enables the OOK mode for the PA, in this case the data to be transmitted are received through the FSK pin.
p2 p1 p0 Relative Output Power [dB]
000
0
001
-3
010
-6
011
-9
100
-12
101
-15
110
-18
111
-21
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).
15
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