SI4421-A0-FT Silicon Laboratories Inc, SI4421-A0-FT Datasheet - Page 32

• Manufacturer Part Number: SI4421-A0-FT
• Description: IC TXRX FSK 915MHZ 3.8V 16-TSSOP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI4421-A0-FT

• Frequency: 433MHz, 868MHz, 915MHz
• Data Rate - Maximum: 256kbps
• Modulation Or Protocol: FSK
• Applications: ISM
• Power - Output: 7dbm
• Sensitivity: -110dBm
• Voltage - Supply: 2.2 V ~ 3.8 V
• Current - Receiving: 15mA
• Current - Transmitting: 28mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1737-5

CRYSTAL SELECTION GUIDELINES
The crystal oscillator of the Si4421 requires a 10 MHz parallel mode crystal. The circuit contains an integrated load capacitor in
order to minimize the external component count. The internal load capacitance value is programmable from 8.5 pF to 16 pF in 0.5
pF steps. With appropriate PCB layout, the total load capacitance value can be 10 pF to 20 pF so a variety of crystal types can be
used.
When the total load capacitance is not more than 20 pF and a worst case 7 pF shunt capacitance (C
crystal, the oscillator is able to start up with any crystal having less than 100 ohms ESR (equivalent series loss resistance). However,
lower C
The crystal frequency is used as the reference of the PLL, which generates the local oscillator frequency (f
directly proportional to the crystal frequency. The accuracy requirements for production tolerance, temperature drift and aging can
thus be determined from the maximum allowable local oscillator frequency error.
Whenever a low frequency error is essential for the application, it is possible to “pull” the crystal to the accurate frequency by
changing the load capacitor value. The widest pulling range can be achieved if the nominal required load capacitance of the crystal is
in the “midrange”, for example 16 pF. The “pull-ability” of the crystal is defined by its motional capacitance and C
Maximum XTAL Tolerances Including Temperature and Aging [ppm]
Bit Rate: 2.4 kbps
Bit Rate: 9.6 kbps
Bit Rate: 38.4 kbps
Bit Rate: 115.2 kbps
0
and ESR values guarantee faster oscillator startup.
433 MHz
868 MHz
915 MHz
433 MHz
868 MHz
915 MHz
433 MHz
868 MHz
915 MHz
433 MHz
868 MHz
915 MHz
don't use
don't use
don't use
don't use
don't use
don't use
105
30
20
10
10
30
15
30
8
8
don't use
don't use
120
45
30
20
15
45
30
15
15
45
5
3
3
3
135
60
50
25
25
60
50
25
25
60
20
10
10
20
10
10
Deviation [± kHz]
Deviation [± kHz]
Deviation [± kHz]
Deviation [± kHz]
150
75
70
30
30
75
70
30
30
75
30
20
15
30
20
15
165
90
90
40
40
90
80
40
40
90
50
25
25
50
25
25
105
100
105
100
105
180
50
50
50
50
75
30
30
70
35
30
0
) value is expected for the
120
100
120
100
120
195
75
40
40
80
60
50
60
50
45
40
LO
0
). Therefore, f
.
Si4421
LO
32
is