SI4430-B1-FMR Silicon Laboratories Inc, SI4430-B1-FMR Datasheet - Page 39

• Manufacturer Part Number: SI4430-B1-FMR
• Description: IC TXRX 900-960MHZ -8-13DB 20QFN
• Manufacturer: Silicon Laboratories Inc

Specifications of SI4430-B1-FMR

• Mfg Application Notes: Transitioning SI4430/31 to Rev B
• Frequency: 900MHz ~ 960MHz
• Data Rate - Maximum: 256kbps
• Modulation Or Protocol: ISM
• Applications: General Purpose
• Power - Output: 13dBm
• Sensitivity: -121dBm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Current - Receiving: 18.5mA
• Current - Transmitting: 30mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-VQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -

the output from the - modulator. The tuning resolution is sufficient to tune to the commanded frequency with a
maximum accuracy of 312.5 Hz anywhere in the range between 240–960 MHz.
5.6.1. VCO
The output of the VCO is automatically divided down to the correct output frequency depending on the hbsel and
fb[4:0] fields in "Register 75h. Frequency Band Select." In receive mode, the LO frequency is automatically shifted
downwards by the IF frequency of 937.5 kHz, allowing transmit and receive operation on the same frequency. The
VCO integrates the resonator inductor and tuning varactor, so no external VCO components are required.
The VCO uses a capacitance bank to cover the wide frequency range specified. The capacitance bank will
automatically be calibrated every time the synthesizer is enabled. In certain fast hopping applications this might not
be desirable so the VCO calibration may be skipped by setting the appropriate register.
5.7. Power Amplifier
The Si4432 contains an internal integrated power amplifier (PA) capable of transmitting at output levels between +1
and +20 dBm. The Si4431/4430 contains a PA which is capable of transmitting output levels between –8 to
+13 dBm. The PA design is single-ended and is implemented as a two stage class CE amplifier with a high
efficiency when transmitting at maximum power. The PA efficiency can only be optimized at one power level.
Changing the output power by adjusting txpow[2:0] will scale both the output power and current but the efficiency
will not remain constant. The PA output is ramped up and down to prevent unwanted spectral splatter.
In the Si4431, the TX and RX may be tied directly. See the TX/RX direct-tie reference design available on the
Silicon Labs website
set to 1.
5.7.1. Output Power Selection
The output power is configurable in 3 dB steps with the txpow[2:0] field in "Register 6Dh. TX Power." Extra output
power can allow the use of a cheaper smaller antenna, greatly reducing the overall BOM cost. The higher power
setting of the chip achieves maximum possible range, but of course comes at the cost of higher TX current
consumption. However, depending on the duty cycle of the system, the effect on battery life may be insignificant.
Contact Silicon Labs Support for help in evaluating this tradeoff.
Add R/W Function/D
6D
R/W
escription
TX Power
for more details. When the direct tie is used, the lna_sw bit in “Register 6Dh. TX Power” must be
reserved
D7
txpow[2:0]
txpow[2:0]
reserved
000
001
010
011
100
101
110
D6
111
000
001
010
100
101
011
110
111
reserved
D5
Rev 1.1
Si4431/30 Output Power
Si4432 Output Power
reserved
+14 dBm
+17 dBm
+20 dBm
+10 dBm
+13 dBm
+11 dBm
+1 dBm
+2 dBm
+5 dBm
+8 dBm
+1 dBm
+4 dBm
+7 dBm
–8 dBm
–5 dBm
–2 dBm
D4
lna_sw txpow[2]
D3
Si4430/31/32-B1
D2
txpow[1]
D1
txpow[0]
D0
POR
Def.
18h
39