SI4355 [SILICON]

EASY-TO-USE, LOW-CURRENT OOK/(G)FSK SUB-GHZ RECEIVER; 易于使用,低电流OOK / ( G) FSK的sub-GHz接收器
SI4355
型号: SI4355
厂家: SILICON    SILICON
描述:

EASY-TO-USE, LOW-CURRENT OOK/(G)FSK SUB-GHZ RECEIVER
易于使用,低电流OOK / ( G) FSK的sub-GHz接收器

文件: 总34页 (文件大小:275K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
Si4355  
EASY-TO-USE, LOW-CURRENT OOK/(G)FSK SUB-GHZ RECEIVER  
Features  
Frequency range =  
Max data rate = 500 kbps  
Power supply = 1.8 to 3.6 V  
64 byte FIFO  
283–960 MHz  
Receive sensitivity  
= –116 dBm  
Auto frequency control (AFC)  
Automatic gain control (AGC)  
Integrated battery voltage sensor  
Modulation  
(G)FSK  
OOK  
Packet handling including  
preamble, sync word detection, and  
CRC  
Low RX Current = 10 mA  
Low standby current = 50 nA  
Low BOM  
20-Pin 3x3 mm QFN package  
Applications  
Pin Assignments  
Remote control  
Remote keyless entry  
Home automation  
Industrial control  
Sensor networks  
Health monitors  
Home security and alarm  
Telemetry  
GND  
SDN  
RXp  
RXn  
NC  
1
20 19 18 17 16 nSEL  
15 SDI  
Garage and gate openers  
2
3
4
5
6
14 SDO  
13 SCLK  
Description  
12 nIRQ  
Silicon Laboratories’ Si4355 is an easy to use, low current, sub-GHz  
GND  
7
8
9
10 11 GPIO1  
®
EZRadio receiver. Covering all major bands, it combines plug-and-play  
simplicity with the flexibility needed to handle a wide variety of  
applications. The compact 3x3 mm package size combined with a low  
external BOM count makes the Si4355 both space efficient and cost  
effective. Excellent sensitivity of 116 dBm allows for a longer operating  
range, while the low current consumption of 10 mA active and 50 nA  
standby, provides for superior battery life. By fully integrating all  
components from the antenna to the GPIO or SPI interface to the MCU,  
the Si4355 makes realizing this performance in an application easy.  
Design simplicity is further exemplified in the Wireless Development Suite  
(WDS) user interface module. This configuration module provides  
simplified programming options for a broad range of applications in an  
easy to use format that results in both a faster and lower risk  
development. Like all Silicon Laboratories’ EZRadio devices, the Si4355  
is fully compliant with all worldwide regulatory standards, such as FCC,  
ETSI, and ARIB.  
Patents pending  
Rev 1.0 7/12  
Copyright © 2012 by Silicon Laboratories  
Si4355  
Si4355  
Functional Block Diagram  
GPIO3  
GPIO2  
XIN XOUT  
Synthesizer  
SDN  
25-32MHz XO  
Rx Chain  
nSEL  
SDI  
RXp  
RXn  
PGA  
LNA  
ADC  
Rx Modem  
SDO  
SCLK  
nIRQ  
Battery  
Voltage  
Sensor  
Aux ADC  
GPIO1  
VDD  
GPIO0  
2
Rev 1.0  
Si4355  
TABLE OF CONTENTS  
Section  
Page  
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4  
1.1. Definition of Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9  
2. Typical Applications Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10  
3. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11  
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11  
3.2. Receiver Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11  
3.3. Receiver Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12  
3.4. Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12  
3.5. Crystal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13  
3.6. Battery Voltage and Auxiliary ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14  
4. Configuration Options and User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15  
4.1. EZConfig GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15  
4.2. Configuration Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16  
4.3. Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18  
5. Controller Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19  
5.1. Serial Peripheral Interface (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19  
5.2. Operating Modes and Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21  
5.3. Application Programming Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24  
5.4. Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25  
5.5. GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25  
6. Data Handling and Packet Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26  
6.1. RX FIFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26  
6.2. Packet Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26  
7. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27  
8. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29  
9. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30  
10. PCB Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32  
11. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33  
11.1. Si4355 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33  
11.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33  
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34  
Rev 1.0  
3
Si4355  
1. Electrical Specifications  
Table 1. Recommended Operating Conditions  
Parameter  
Symbol  
Test Condition  
Min  
Typ  
Max  
Unit  
Ambient Temperature  
Supply Voltage  
T
–40  
1.8  
25  
85  
C  
V
A
V
3.6  
DD  
I/O Drive Voltage  
V
V
GPIO  
1.8  
3.6  
Table 2. DC Characteristics1  
Parameter  
Symbol  
Conditions  
Min Typ Max Units  
Supply Voltage  
Range  
V
1.8 3.3  
3.6  
V
DD  
Power Saving Modes  
RC oscillator, main digital regulator, and low power  
digital regulator OFF  
I
30  
50  
nA  
nA  
Shutdown  
Register values maintained and  
RC oscillator/WUT OFF  
I
Standby  
Crystal Oscillator and Main Digital Regulator ON,  
all other blocks OFF  
I
2
mA  
mA  
Ready  
I
SPI Active State  
RX Tune  
1.35  
SPI Active  
TUNE Mode Current  
RX Mode Current  
I
6.5  
10  
mA  
mA  
Tune_RX  
I
RX  
Notes:  
1. All specifications guaranteed by production test unless otherwise noted. Production test conditions and max limits are  
listed in the "Production Test Conditions" section of "1.1. Definition of Test Conditions" on page 9.  
2. Guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test Conditions" section in "1.1.  
Definition of Test Conditions" on page 9.  
4
Rev 1.0  
Si4355  
Table 3. Synthesizer AC Electrical Characteristics1  
Parameter  
Symbol  
Conditions  
Min  
Typ  
Max Units  
Synthesizer Frequency  
Range  
F
SYN  
283  
350  
525  
960  
MHz  
MHz  
MHz  
425  
850  
Synthesizer Frequency  
Resolution  
F
F
F
114.4  
57.2  
38.1  
Hz  
Hz  
Hz  
RES-960  
RES-525  
RES-350  
850–960 MHz  
425–525 MHz  
283–350 MHz  
2
2
t
Measured from exiting Ready mode with  
XOSC running to any frequency,  
including VCO Calibration  
Synthesizer Settling Time  
LOCK  
130  
µs  
Notes:  
1. All specifications guaranteed by production test unless otherwise noted. Production test conditions and max limits are  
listed in the "Production Test Conditions" section in "1.1. Definition of Test Conditions" on page 9.  
2. Guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test Conditions" section in "1.1.  
Definition of Test Conditions" on page 9.  
Table 4. Receiver AC Electrical Characteristics1  
Parameter  
RX Frequency  
Range  
Symbol  
Conditions  
Min  
283  
425  
850  
Typ  
Max Units  
F
350  
525  
960  
MHz  
MHz  
MHz  
dBm  
RX  
RX Sensitivity  
P
(BER < 0.1%)  
–116  
RX-_2  
(2.4 kbps, GFSK, BT = 0.5,  
2
f = 30 kHz) ,114 kHz Rx BW  
P
(BER < 0.1%)  
–108  
–103  
dBm  
dBm  
RX-_40  
(40 kbps, GFSK, BT = 0.5,  
2
f = 25 kHz) , 114 kHz Rx BW  
P
(BER < 0.1%)  
RX-_128  
(128 kbps, GFSK, BT = 0.5,  
2
f = 70 kHz) , 305 kHz Rx BW  
P
BER < 0.1%, 1 kbps, 185 kHz Rx BW,  
OOK, PN15 data  
40  
–113  
–102  
dBm  
dBm  
kHz  
RX-_OOK  
BER < 0.1%, 40 kbps, 185 kHz Rx BW,  
OOK, PN15 data  
2
RX Channel Bandwidth  
BW  
850  
Notes:  
1. All specifications guaranteed by production test unless otherwise noted. Production test conditions and max limits are  
listed in the "Production Test Conditions" section in "1.1. Definition of Test Conditions" on page 9.  
2. Guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test Conditions" section in "1.1.  
Definition of Test Conditions" on page 9.  
Rev 1.0  
5
Si4355  
Table 4. Receiver AC Electrical Characteristics1 (Continued)  
Parameter  
Symbol  
Conditions  
Min  
Typ  
Max Units  
BER Variation vs Power  
Level  
P
Up to +5 dBm Input Level  
0
0.1  
ppm  
RX_RES  
2
RSSI Resolution  
RES  
C/I  
±0.5  
–56  
–59  
dB  
dB  
dB  
RSSI  
2
1-Ch Offset Selectivity  
2-Ch Offset Selectivity  
Desired Ref Signal 3 dB above sensitiv-  
ity, BER < 0.1%. Interferer is CW and  
desired modulated with  
1-CH  
2-CH  
2
C/I  
1.2 kbps F = 5.2 kHz GFSK with  
BT = 0.5,  
Rx BW = 58 kHz,  
channel spacing = 100 kHz  
200K  
1M  
Desired Ref Signal 3 dB above sensitiv-  
ity, BER < 0.1% Interferer is CW and  
desired modulated with 1.2 kbps  
F = 5.2 kHz GFSK with BT = 0.5,  
RX BW = 58 kHz  
–58  
–61  
–79  
dB  
dB  
dB  
Blocking 200 kHz–1 MHz  
BLOCK  
2
Blocking 1 MHz Offset  
BLOCK  
BLOCK  
2
8M  
Blocking 8 MHz Offset  
2
Im  
Rejection at the image frequency.  
IF = 468 kHz  
–40  
dB  
Image Rejection  
REJ  
2
P
Measured at RX pins  
–54  
dBm  
Spurious Emissions  
OB_RX1  
Notes:  
1. All specifications guaranteed by production test unless otherwise noted. Production test conditions and max limits are  
listed in the "Production Test Conditions" section in "1.1. Definition of Test Conditions" on page 9.  
2. Guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test Conditions" section in "1.1.  
Definition of Test Conditions" on page 9.  
Table 5. Auxiliary Block Specifications1  
Parameter  
Symbol  
Conditions  
Min  
Typ  
Max  
Units  
2
XTAL Range  
XTAL-  
25  
32  
MHz  
RANGE  
30 MHz XTAL Start-Up Time  
t
Using XTAL and board layout in  
reference design. Start-up time  
will vary with XTAL type and  
board layout  
250  
µs  
30M  
30 MHz XTAL Cap  
Resolution  
30M  
70  
5
fF  
RES  
3
POR Reset Time  
t
ms  
POR  
Notes:  
1. All specifications guaranteed by production test unless otherwise noted. Production test conditions and max limits are  
listed in the "Production Test Conditions" section in "1.1. Definition of Test Conditions" on page 9.  
2. XTAL Range tested in production using an external clock source (similar to using a TCXO).  
3. Guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test Conditions" section in "1.1.  
Definition of Test Conditions" on page 9.  
6
Rev 1.0  
Si4355  
Table 6. Digital IO Specifications (GPIO_x, SCLK, SDO, SDI, nSEL, nIRQ)1  
Parameter  
Symbol  
Conditions  
0.1 x V to 0.9 x V ,  
DD  
Min  
Typ  
Max  
Units  
Rise Time  
Fall Time  
T
2.3  
ns  
RISE  
DD  
C = 10 pF, DRV<1:0>=HH  
L
T
0.9 x V to 0.1 x V  
2
ns  
FALL  
DD  
DD,  
C = 10 pF, DRV<1:0>=HH  
L
Input Capacitance  
C
V
2
pF  
V
IN  
Logic High Level Input Voltage  
Logic Low Level Input Voltage  
Input Current  
V
x 0.7  
IH  
DD  
V
–10  
1
V
x 0.3  
DD  
V
IL  
I
0<V < V  
DD  
10  
10  
µA  
µA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
mA  
V
IN  
IN  
Input Current If Pullup is Activated  
Drive Strength for Output Low  
I
V = 0 V  
INP  
IL  
I
DRV<1:0> = LL  
DRV<1:0> = LH  
DRV<1:0> = HL  
DRV<1:0> = HH  
DRV<1:0> = LL  
DRV<1:0> = LH  
DRV<1:0> = HL  
DRV<1:0> = HH  
DRV<1:0> = LL  
DRV<1:0> = LH  
DRV<1:0> = HL  
DRV<1:0> = HH  
2.1  
1.5  
1.0  
0.4  
4.5  
3.3  
2.1  
0.7  
1.9  
1.7  
1.3  
0.6  
OLL  
OLH  
OHL  
OHH  
2
Level  
I
I
I
Drive Strength for Output High  
Level (GPIO1, GPIO2, GPIO3)  
I
OLL  
OLH  
OHL  
OHH  
2
I
I
I
Drive Strength for Output High  
Level (GPIO0)  
I
OLL  
OLH  
OHL  
OHH  
2
I
I
I
Logic High Level Output Voltage  
Logic Low Level Output Voltage  
Notes:  
V
I
= 500 µA  
= 500 µA  
V x 0.8  
DD  
OH  
OUT  
OUT  
V
I
V
x 0.2  
DD  
V
OL  
1. All specifications guaranteed by qualification. Qualification test conditions are listed in the "Qualification Test  
Conditions" section in "1.1. Definition of Test Conditions" on page 9.  
2. GPIO output current measured at 3.3 VDC VDD with VOH = 2.7 VDC and VOL = 0.66 VDC.  
Rev 1.0  
7
Si4355  
Table 7. Thermal Characteristics  
Parameter  
Thermal Resistance Junction to Ambient  
Junction Temperature  
Symbol  
Test Condition  
Value  
30  
Unit  
C/W  
C  
Still Air  
JA  
125  
T
J
Table 8. Absolute Maximum Ratings  
Parameter  
Value  
–0.3, +3.6  
–0.3, V + 0.3  
Unit  
V
to GND  
V
V
DD  
Voltage on Digital Control Inputs  
Voltage on Analog Inputs  
RX Input Power  
DD  
–0.3, V + 0.3  
V
DD  
+10  
dBm  
C  
C  
Operating Ambient Temperature Range T  
–40 to +85  
–55 to +125  
A
Storage Temperature Range T  
STG  
Note: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These  
are stress ratings only and functional operation of the device at or beyond these ratings in the operational sections of  
the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect  
device reliability. Caution: ESD sensitive device.  
8
Rev 1.0  
Si4355  
1.1. Definition of Test Conditions  
Production Test Conditions:  
T = +25 °C  
A
V  
= +3.3 VDC  
DD  
Sensitivity measured at 434 MHz using a PN15 modulated input signal and with packet handler mode  
enabled.  
External reference signal (XIN) = 1.0 V at 30 MHz, centered around 0.8 VDC  
PP  
Production test schematic (unless noted otherwise)  
All RF input and output levels referred to the pins of the Si4355 (not the RF module)  
Qualification Test Conditions:  
T = –40 to +85 °C (typical = 25 °C)  
A
V  
= +1.8 to +3.6 VDC (typical = 3.3 VDC)  
DD  
Using reference design or production test schematic  
All RF input and output levels referred to the pins of the Si4355 (not the RF module)  
Rev 1.0  
9
Si4355  
2. Typical Applications Circuit  
30 MHz  
SDN  
GP1  
C2  
GP2  
GP3  
GP4  
GP5  
GND  
SDI  
1
2
3
15  
14  
13  
SDN  
SDO  
SCLK  
nIRQ  
GPIO1  
L2  
C1  
RXp  
RXn  
NC  
L1  
Si4355  
4
5
12  
11  
VDD  
C3  
100 p  
C4  
C5  
100 n  
1u  
Figure 1. Si4355 Applications Circuit  
10  
Rev 1.0  
Si4355  
3. Functional Description  
GPIO3  
GPIO2  
XIN XOUT  
Synthesizer  
SDN  
25-32MHz XO  
Rx Chain  
nSEL  
SDI  
RXp  
LNA  
RXn  
PGA  
ADC  
Rx Modem  
SDO  
SCLK  
nIRQ  
Battery  
Voltage  
Sensor  
Aux ADC  
GPIO1  
VDD  
GPIO0  
Figure 2. Si4355 Functional Block Diagram  
3.1. Overview  
The Si4355 is an easy-to-use, size efficient, low current wireless ISM receiver that covers the sub-GHz bands. The  
wide operating voltage range of 1.8–3.6 V and low current consumption make the Si4355 an ideal solution for  
battery powered applications. The Si4355 uses a single-conversion mixer to downconvert the FSK/GFSK or OOK  
modulated receive signal to a low IF frequency. Following a programmable gain amplifier (PGA) the signal is  
converted to the digital domain by a high performance  ADC allowing filtering, demodulation, slicing, and packet  
handling to be performed in the built-in DSP, increasing the receiver’s performance and flexibility versus analog  
based architectures. The demodulated signal is output to the system MCU through a programmable GPIO or via  
the standard SPI bus by reading the 64-byte Rx FIFO.  
A high precision local oscillator (LO) is used and is generated by an integrated VCO and  Fractional-N PLL  
synthesizer. The Si4355 operates in the frequency bands of 283–350, 425–525, and 850–960 MHz.  
Additional system features, such as 64 byte Rx FIFO, preamble detection, sync word detector and CRC, reduce  
overall current consumption, and allow for the use of lower-cost system MCUs. Power-on-reset (POR), and GPIOs  
further reduce overall system cost and size. The Si4355 is designed to work with an MCU, crystal, and a few  
passives to create a very compact and low-cost system.  
3.2. Receiver Chain  
The internal low-noise amplifier (LNA) is designed to be a wide-band LNA that can be matched with three external  
discrete components to cover any common range of frequencies in the sub-GHz band. The LNA has extremely low  
noise to suppress the noise of the following stages and achieve optimal sensitivity; so, no external gain or front-end  
modules are necessary. The LNA has gain control, which is controlled by the internal automatic gain control (AGC)  
algorithm. The LNA is followed by an I-Q mixer, filter, programmable gain amplifier (PGA), and ADC. The I-Q  
mixers downconvert the signal to an intermediate frequency. The PGA then boosts the gain to be within dynamic  
range of the ADC. The ADC rejects out-of-band blockers and converts the signal to the digital domain where  
filtering, demodulation, and processing is performed. Peak detectors are integrated at the output of the LNA and  
PGA for use in the AGC algorithm.  
Rev 1.0  
11  
Si4355  
3.3. Receiver Modem  
Using high-performance ADCs allows channel filtering, image rejection, and demodulation to be performed in the  
digital domain, which allows for flexibility in optimizing the device for particular applications. The digital modem  
performs the following functions:  
Channel selection filter  
Preamble detection  
Invalid preamble detection  
RX demodulation  
Automatic gain control (AGC)  
Automatic frequency compensation (AFC)  
Radio signal strength indicator (RSSI)  
Cyclic redundancy check (CRC)  
The digital channel filter and demodulator are optimized for ultra-low-power consumption and are highly  
configurable. Supported modulation types are GFSK, FSK, and OOK. The channel filter can be configured to  
support bandwidths ranging from 850 kHz down to 40 kHz. A large variety of data rates are supported ranging from  
500 kbps up to 500 kbps. The configurable preamble detector is used with the synchronous demodulator to  
improve the reliability of the sync-word detection. Preamble detection can be skipped using only sync detection,  
which is a valuable feature of the asynchronous demodulator when very short preambles are used. The received  
signal strength indicator (RSSI) provides a measure of the signal strength received on the tuned channel. The  
resolution of the RSSI is 0.5 dB. This high-resolution RSSI enables accurate channel power measurements for  
clear channel assessment (CCA), carrier sense (CS), and listen before talk (LBT) functionality. A wireless  
communication channel can be corrupted by noise and interference, so it is important to know if the received data  
is free of errors. A cyclic redundancy check (CRC) is used to detect the presence of erroneous bits in each packet.  
A CRC is computed and appended at the end of each transmitted packet and verified by the Si4355 receiver to  
confirm that no errors have occurred. The packet handler and CRC can significantly reduce the load on the system  
microcontroller allowing for a simpler and cheaper microcontroller. The default bandwidth-time product (BT) is 0.5  
for all programmed data rates.  
3.3.1. Received Signal Strength Indicator  
The received signal strength indicator (RSSI) is an estimate of the signal strength in the channel to which the  
receiver is tuned. The RSSI measurement is done after the channel filter, so it is only a measurement of the  
desired or undesired in-band signal power. The Si4355 uses a fast response register to read RSSI and so can  
complete the read in 16 SPI clock cycles with no requirement to wait for CTS. The RSSI value is read using the  
RSSI_READ command. The RSSI value reported by this API command can be converted to dBm using the  
following equation:  
RSSI_value  
--------------------------------  
RSSIcal  
RSSIdBm  
=
2
RSSIcal in this formula is dependent on the matching network, modem settings, and external LNA gain (if present).  
It can be obtained through lab measurements using a signal generator connected to the antenna input to provide a  
known RSSI level. Without an external LNA, the RSSIcal will be approximately 130.  
3.4. Synthesizer  
The Si4355 includes an integrated Sigma Delta () Fractional-N PLL synthesizer capable of operating over the  
bands from 283–350, 425–525, and 850–960 MHz. The synthesizer has many advantages; it provides flexibility  
in choosing data rate, deviation, channel frequency, and channel spacing. The frequency resolution is  
19  
19  
18  
(2/3)Freq_xo/(2 ) for 283–350 MHz, Freq_xo/(2 ) for 425–525 MHz, and Freq_xo/(2 ) for 850–960 MHz. The  
nominal reference frequency to the PLL is 30 MHz, but any XTAL frequency from 25 to 32 MHz may be used. The  
modem configuration calculator in WDS will automatically account for the XTAL frequency being used. The PLL  
utilizes a differential LC VCO with integrated on-chip inductors. The output of the VCO is followed by a configurable  
divider, which will divide the signal down to the desired output frequency band.  
12  
Rev 1.0  
Si4355  
3.4.1. Synthesizer Frequency Control  
The frequency is set by changing the integer and fractional settings to the synthesizer. The WDS calculator will  
automatically provide these settings, but the synthesizer equation is shown below for convenience. Initial  
frequency settings are configured in the EZConfig setup and can also be modified using the API commands:  
FREQ_CONTROL_INTE,  
FREQ_CONTROL_FRAC0.  
FREQ_CONTROL_FRAC2,  
FREQ_CONTROL_FRAC1,  
and  
fc_frac  
219  
4 freq_xo  
------------------------------  
Hz  
------------------  
RF_channel = fc_inte +  
outdiv  
Note: The fc_frac/219 value in the above formula must be a number between 1 and 2. The LSB of fc_frac must be "1".  
Table 9. Output Divider (Outdiv) Values  
Outdiv  
Lower (MHz)  
Upper (MHz)  
12  
8
284  
425  
850  
350  
525  
960  
4
3.4.1.1. EZ Frequency Programming  
EZ frequency programming allows for easily changing radio frequency using a single API command. The base  
frequency is first set using the EZConfig setup. This base frequency will correspond to channel 0. Next, a channel  
step size is also programmed within the EZConfig setup. The resulting frequency will be:  
RF Frequency = Base Frequency + Channel Step Size  
The second argument of the START_RX is CHANNEL, which sets the channel number for EZ frequency  
programming. For example, if the channel step size is set to 1 MHz, the base frequency is set to 900 MHz, and a  
CHANNEL number of 5 is programmed during the START_RX command, the resulting frequency will be 905 MHz.  
If no CHANNEL argument is written as part of the START_RX command, it will default to the previous value. The  
initial value of CHANNEL is 0 and so will be set to the base frequency if this argument is never used.  
3.5. Crystal Oscillator  
The Si4355 includes an integrated crystal oscillator with a fast start-up time of less than 250 µs. The design is  
differential with the required crystal load capacitance integrated on-chip to minimize the number of external  
components. By default, all that is required off-chip is the crystal. The default crystal is 30 MHz, but the circuit is  
designed to handle any XTAL from 25 to 32 MHz, set in the EZConfig setup. The crystal load capacitance can be  
digitally programmed to accommodate crystals with various load capacitance requirements and to adjust the  
frequency of the crystal oscillator. The tuning of the crystal load capacitance is programmed through the  
GLOBAL_XO_TUNE API property. The total internal capacitance is 11 pF and is adjustable in 127 steps (70  
fF/step). The crystal frequency adjustment can be used to compensate for crystal production tolerances. The  
frequency offset characteristics of the capacitor bank are demonstrated in Figure 3.  
Rev 1.0  
13  
Si4355  
Figure 3. Capacitor Bank Frequency Offset Characteristics  
3.6. Battery Voltage and Auxiliary ADC  
The Si4355 contains an integrated auxiliary 11-bit ADC used for the internal battery voltage detector or an external  
component via GPIO. The Effective Number of Bits (ENOB) is 9 bits. When measuring external components, the  
input voltage range is 1 V, and the conversion rate is between 300 Hz to 2.44 kHz. The ADC value is read by first  
sending the GET_ADC_READING command and enabling the desired inputs. When the conversion is finished and  
all the data is ready, CTS will go high, and the data can be read out. Refer to application note, “AN691: EZRadio  
API Guide”, for details on this command and the formulas needed to interpret the results.  
14  
Rev 1.0  
Si4355  
4. Configuration Options and User Interface  
4.1. EZConfig GUI  
The EZConfig Setup GUI is part of the Wireless Development Suite (WDS) program. This setup interface provides  
an easy path for quickly selecting and loading the desired configuration for the device. The EZConfig Setup allows  
for three different methods for device setup. One option is the configuration wizard, which easily identifies the  
optimal setup based on a few questions about the application. Another option is the configuration table, which  
provides a list of preloaded, common configurations. Lastly, EZConfig allows for custom configuration to be loaded  
using the radio configuration application. After the desired configuration is selected, the EZConfig setup  
automatically creates the configuration array that will be passed to the chip for setup. The program then gives the  
option to load a sample project with the selected configuration onto the evaluation board, or launch IDE with the  
new configuration array preloaded into the user program. For more complete information on EZConfig usage, refer  
to the application note, “AN692: Si4x55 Programming Guide & Sample Codes”.  
Open EZConfig  
Setup in WDS  
Input Method  
Fast  
Guided  
Manual  
Run  
Configuration  
Wizard  
Select  
Configuration  
from Table  
Create Custom  
Configuration  
Select Freq,  
Power, and  
Packet Handler  
Features  
Select Action  
Write New Code  
Lab Measurement  
Run Sample Code  
Add new  
Open IDE with  
configuration  
array preloaded  
Load  
Configuration on  
Device  
configuration to  
sample code and  
load on board  
Figure 4. Device Configuration Steps  
Rev 1.0  
15  
Si4355  
4.1.1. Configuration Wizard  
The configuration wizard is available to easily identify the optimal device setup based on a few questions about the  
desired application. Within this wizard, the user is able to define their system requirements and can see some  
potential trade-offs for various settings. The wizard then provides a recommended configuration that is optimized  
for the given application. This configuration can be further modified if needed to provide the desired setup.  
4.1.2. Configuration Table  
The configuration table is a list of predefined configurations that have been optimized for performance and  
validated by Silicon Labs. These configurations are listed for many common application conditions and so most  
users will be able to find the configuration they need in this table. These configurations are set to provide optimized  
performance for a given application and can be implemented with low design risk. Once the list item is selected,  
the specific frequency, and packet handler features can also be applied.  
4.1.3. Radio Configuration Application  
The Radio Configuration Application provides an intuitive interface for directly modifying the device configuration.  
Using this control panel, the device parameters such as modulation type, data rate, and frequency deviation, can  
be set. The EZConfig Setup then takes these parameters and automatically determines the appropriate device  
register settings. This method allows the user to have complete flexibility in determining the configuration of the  
device without the need to translate the system requirements into device specific properties. As with the other  
EZConfig methods, the resulting configuration array is automatically generated and available for use in the user's  
program.  
4.2. Configuration Options  
4.2.1. Frequency Band  
The Si4355 can operate in the 283–350 MHz, 425–525 MHz, or 850–960 MHz bands. One of these three bands  
will be selected during the configuration setup and then the specific receive frequency that will be used within this  
band can be selected.  
4.2.2. Modulation Type  
The Si4355 can operate using On/Off Keying (OOK), Frequency Shift Keying (FSK), or Gaussian Frequency Shift  
Keying (GFSK). OOK modulation is the most basic modulation type available. It is the most power efficient method  
and does not require as high oscillator accuracy as FSK. FSK provides the best sensitivity and, therefore, range  
performance but generally requires more precision from the oscillator used. GFSK is a version of FSK where the  
signal is passed through a Gaussian filter, limiting its spectral width. As a result, the out of band components of the  
signal are reduced.  
The Si4355 also has an option for Manchester coding. This method provides a state transition at each bit and so  
allows for more reliable clock recovery.  
Clock  
Data  
1
1
1
0
1
0
0
1
Manchester  
Figure 5. Manchester Code Example  
16  
Rev 1.0  
Si4355  
4.2.3. Frequency Deviation  
If FSK or GFSK modulation is selected, then a frequency deviation will also need to be selected. The frequency  
deviation is the maximum instantaneous difference between the FM modulated frequency and the nominal carrier  
frequency. The Si4455 can operate across a wide range of data rates and frequency deviations. If a frequency  
deviation needs to be selected, the following guideline might be helpful to build a robust link. A proper frequency  
deviation is linked to the frequency error between transmitter and receiver. The frequency error can be calculated  
using the crystal tolerance parameters and the RF operating frequency: (ppm_tx+ppm_rx)*Frf/1E-6. For frequency  
errors below 50 kHz, the deviation can be about the same as the frequency error. For frequency errors exceeding  
50 kHz the frequency deviation can be set to about 0.75 times the frequency error. It is advised to position the  
modulation index (=2*freq_dev/data_rate) into a range between 1 and 100 for Packet Handling mode and 2 to 100  
for direct mode (non-standard preamble). For example, when in Packet Handling mode and the frequency error is  
smaller than data_rate/2, the frequency deviation is set to about data_rate/2. When the frequency error exceeds  
100xdata_rate/2, the frequency deviation is preferred to be set to 100xdata_rate/2.  
4.2.4. Data Rate  
The Si4355 can be set to communicate at between 1 to 500 kbps in (G)FSK mode and between 0.5 to 120 kbps in  
OOK mode. Higher data rates allow for faster data transfer while lower data rates result in improved sensitivity and  
range performance.  
4.2.5. Channel Bandwidth  
The channel bandwidth sets the bandwidth for the receiver. Since the receiver bandwidth is directly proportional to  
the noise allowed in the system, this will normally be set as low as possible. The specific channel bandwidth used  
will usually be determined based upon the precision of the oscillator and the frequency deviation of the transmitted  
signal. The EZConfig setup can provide the recommended channel bandwidth based upon these two parameters  
to help optimize the system.  
4.2.6. Preamble Length  
A preamble is a defined simple bit sequence used to notify the receiver that a data transmission is imminent. The  
length of this preamble will normally be set as short as possible to minimize power while still insuring that it will be  
reliably detected given the receiver characteristics, such as duty cycling and packet error rate performance. The  
Si4355 allows the preamble length to be set between 3 to 255 bytes in length with a default length of 4 bytes. The  
preamble pattern for the Si4355 will always be 55h with a first bit of "0" if the packet handler capability is used.  
4.2.7. Sync Word Length and Pattern  
The sync word follows the preamble in the packet structure and is used to identify the start of the payload data and  
to synchronize the receiver to the transmitted bit stream. The Si4355 allows for sync word lengths of 1 to 4 bytes  
and the specific pattern can be set within the EZConfig program. The default is a 2 byte length 2d d4 pattern.  
4.2.8. Cyclic Redundancy Check (CRC)  
CRC is used to verify that no errors have occurred during transmission and the received packet has exactly the  
same data as it did when transmitted. If this function is enabled in the Si4355, the last byte of transmitted data must  
include the CRC generated by the transmitter. The Si4355 then performs a CRC calculation on the received packet  
and compares that to the transmitted CRC. If these two values are the same, the Si4355 will set an interrupt  
indicating a valid packet has been received and is waiting in the Rx FIFO. If these two CRC values differ, the  
Si4355 will flag an interrupt indicating that a packet error occurred. The Si4355 uses CRC(16)-IBM: x16+x15+x2+1  
with a seed of 0xFFFF.  
Rev 1.0  
17  
Si4355  
4.3. Configuration Commands  
The EZConfig Setup provides all of the code needed for basic radio configuration. Once the setup is completed in  
the GUI, the program outputs configuration array(s) that can be sent to the radio via the SPI interface. No  
additional setup coding is needed. The configuration command process is shown in Figure 6. The  
EZCONFIG_SETUP passes the configuration array to the device and the EZCONFIG_CHECK insures that all of  
the configuration data was written correctly. For more information on the setup commands, refer to application  
note, “AN691: EZRadio API Guide”.  
EZCONFIG_SETUP  
NOP  
EZCONFIG_SETUP  
EZCONFIG_CHECK  
Figure 6. Configuration Command Flowchart  
18  
Rev 1.0  
Si4355  
5. Controller Interface  
5.1. Serial Peripheral Interface (SPI)  
The Si4355 communicates with the host MCU over a standard 4-wire serial peripheral interface (SPI): SCLK, SDI,  
SDO, and nSEL. The SPI interface is designed to operate at a maximum of 10 MHz. The SPI timing parameters  
are listed in Table 10. The host MCU writes data over the SDI pin and can read data from the device on the SDO  
output pin. Figure 7 shows an SPI write command. The nSEL pin should go low to initiate the SPI command. The  
first byte of SDI data will be one of the API commands followed by n bytes of parameter data, which will be variable  
depending on the specific command. The rising edges of SCLK should be aligned with the center of the SDI data.  
Table 10. Serial Interface Timing Parameters  
Symbol  
Parameter  
Min (ns)  
Diagram  
Clock high time  
t
40  
40  
20  
20  
20  
CH  
Clock low time  
Data setup time  
Data hold time  
t
CL  
DS  
DH  
DD  
SCLK  
t
tSS  
tCL  
tCH  
tDS tDH  
tDD  
tSH  
tDE  
t
t
Output data delay  
time  
SDN  
SDO  
Output enable time  
Output disable time  
Select setup time  
Select hold time  
t
t
20  
50  
20  
50  
80  
EN  
DE  
tEN  
tSW  
t
SS  
SH  
nSEL  
t
Select high period  
t
SW  
nSEL  
SDO  
SDI  
API Command  
ParamByte 0  
ParamByte n  
SCLK  
Figure 7. SPI Write Command  
The Si4355 contains an internal MCU which controls all the internal functions of the radio. For SPI read  
commands, a typical communication flow of checking clear-to-send (CTS) is used to make sure the internal MCU  
has executed the command and prepared the data to be output over the SDO pin. Figure 8 demonstrates the  
general flow of an SPI read command. Once the CTS value reads FFh, the read data is ready to be clocked out to  
the host MCU. The typical time for a valid FFh CTS reading is 20 µs. Figure 9 demonstrates the remaining read  
cycle after CTS is set to FFh. The internal MCU will clock out the SDO data on the negative edge so the host MCU  
should process the SDO data on the rising edge of SCLK.  
Rev 1.0  
19  
Si4355  
0xFF  
Retrieve  
Response  
Send Command  
Read CTS  
CTS Value  
0x00  
nSEL  
SDO  
SDI  
CTS  
ReadCmdBuff  
SCLK  
Figure 8. SPI Read Command—Check CTS Value  
nSEL  
SDO  
SDI  
Response Byte 0  
Response Byte n  
SCLK  
Figure 9. SPI Read Command—Clock Out Read Data  
20  
Rev 1.0  
Si4355  
5.2. Operating Modes and Timing  
The primary states of the Si4355 are shown in Figure 10. The shutdown state completely shuts down the radio,  
minimizing current consumption and is controlled using the SDN (pin 2). All other states are controlled using the  
API commands START_RX and CHANGE_STATE. Table 11 shows each of the operating modes with the time  
required to reach either RX state as well as the current consumption of each state. The times in Table 11 are  
measured from the rising edge of nSEL until the chip is in the desired state. This information is included for  
reference only since an automatic sequencer moves the chip from one state to another and so it is not necessary  
to manually step through each state. Most applications will utilize the standby mode since this provides the fastest  
transition response time, maintains all register values, and results in nearly the same current consumption as  
shutdown.  
Standby  
Shutdown  
SPI Active  
Config  
Ready  
Rx Tune  
Rx  
Figure 10. State Machine Diagram  
Table 11. Operating State Response Time and Current Consumption  
State / Mode  
Shutdown  
Standby  
SPI Active  
Ready  
Response Time to Rx Current in State / Mode  
30 ms  
460 μs  
330 μs  
130 μs  
75 μs  
30 nA  
50 nA  
1.35 mA  
1.8 mA  
6.5 mA  
10 mA  
Rx Tune  
Rx  
150 μs  
Rev 1.0  
21  
Si4355  
5.2.1. Shutdown State  
The shutdown state is the lowest current consumption state of the device and is entered by driving SDN (Pin 2)  
high. In this state, all register contents are lost and there is no SPI access. To exit this mode, drive SDN low. The  
device will then initiate a power on reset (POR) along with internal calibrations. Once this POR period is complete,  
the POWER_UP command is required to initialize the radio and the configuration can then be loaded into the  
device. The SDN pin must be held high for at least 10 µs before driving it low again to insure the POR can be  
executed correctly. The shutdown state can be used to fully reset the part.  
5.2.2. Standby State  
The standby state has similar current consumption to the shutdown state but retains all register values, allowing for  
a much faster response time. Because of these benefits, most applications will want to use standby mode rather  
than shutdown. The standby state is entered by using the CHANGE_STATE API command. While in this state, the  
SPI is accessible but any SPI event will automatically transition the chip to the SPI active state. After the SPI event,  
the host will need to re-command the device to standby mode.  
5.2.3. SPI Active State  
The SPI active state enables the device to process any SPI events, such as API commands. In this state, the SPI  
and boot up oscillator are enabled. The SPI active state is entered by using the CHANGE_STATE command or  
automatically through an SPI event while in standby mode. If the SPI active state was entered automatically from  
standby mode, a CHANGE_STATE command will be needed to return the device to standby mode.  
5.2.4. Ready State  
Ready state is designed to give a fast transition time to RX state with minimized current consumption. In this mode  
the crystal oscillator remains enabled to minimize the transition time. Ready state can be entered using the  
CHANGE_STATE command.  
5.2.5. Power On Reset  
A Power On Reset (POR) sequence is used to boot the device up from a fully off or shutdown state. To execute this  
process, VDD must ramp within 1ms and must remain applied to the device for at least 10ms. If VDD is removed,  
then it must stay below 0.15V for at least 10ms before being applied again. Please see Figure x and Table x for  
details.  
Figure 11. POR Timing Diagram  
22  
Rev 1.0  
Si4355  
Table 12. POR Timing  
Variable  
Description  
Min  
Typ  
Max Units  
High time for VDD to fully settle POR circuit.  
Low time for VDD to enable POR.  
Voltage for successful POR.  
t
10  
ms  
ms  
V
PORH  
t
10  
90%*Vdd  
0
PORL  
V
RRH  
Starting Voltage for successful POR.  
Slew rate of VDD for successful POR.  
V
150  
1
mV  
ms  
RRL  
t
SR  
5.2.6. RX State  
The RX state is used whenever the device is required to receive data. It is entered using either the START_RX or  
CHANGE_STATE commands. With the START_RX command, the next state can be defined to insure optimal  
timing. When either command is sent to enter RX state, an internal sequencer automatically takes care of all  
actions required to move between states with no additional user commands needed. The sequencer controlled  
events can include enable the digital and analog LDOs, start up the crystal oscillator, enable PLL, calibrate VCO,  
enable receiver circuits, and enable receive mode. The device will also automatically set up all receiver features  
such as packet handling based upon the initial configuration of the device.  
Rev 1.0  
23  
Si4355  
5.3. Application Programming Interface  
An Application Programming Interface (API) is embedded inside the device and is used for communications with  
the host MCU. API commands are used to configure the device, control the chip during operation, and retrieve its  
status. Available commands are shown in Table 13. The complete list of commands and their descriptions are  
provided in application note, “AN691: EZRadio API Guide”.  
Table 13. API Commands  
#
Name  
Description  
NOP  
No operation command  
0x00  
0x01  
0x02  
0x10  
0x11  
0x12  
0x13  
0x14  
0x15  
0x19  
0x20  
0x32  
0x33  
0x34  
0x44  
0x50  
0x51  
0x53  
0x57  
0x66  
0x77  
PART_INFO  
POWER_UP  
FUNC_INFO  
Reports basic information about the device  
Boot options and crystal frequency offset  
Returns the function revision information of the device  
Sets the value of a property  
SET_PROPERTY  
GET_PROPERTY  
Retrieves the value of a property  
GPIO_PIN_CFG  
Configures the GPIO pins  
GET_ADC_READING  
FIFO_INFO  
Performs and retrieves ADC conversion results  
Provides access to the RX FIFO counts and reset  
Validates the EZConfig array was written correctly  
Returns the interrupt status byte  
EZCONFIG_CHECK  
GET_INT_STATUS  
START_RX  
Switches to RX state  
REQUEST_DEVICE_STATE  
CHANGE_STATE  
Request current device state  
Changes to a specified device state / mode  
Used to read CTS and the command response  
CHIP_STATUS_INT_PEND fast response register  
MODEM_INT_PEND fast response register  
PH_INT_PEND fast response register  
RSSI fast response register  
READ_CMD_BUFF  
CHIP_STATUS_INT_PEND_READ  
MODEM_INT_PEND_READ  
PH_INT_PEND_READ  
RSSI_READ  
EZCONFIG_SETUP  
READ_RX_FIFO  
Configures device using EZConfig array  
Reads the RX FIFO  
24  
Rev 1.0  
Si4355  
5.4. Interrupts  
The Si4355 is capable of generating an interrupt signal when certain events occur. The chip notifies the  
microcontroller that an interrupt event has occurred by setting the nIRQ output pin LOW = 0. This interrupt signal  
will be generated when any one (or more) of the interrupt events occur. The nIRQ pin will remain low until the  
microcontroller reads the Interrupt Status Registers. The nIRQ output signal will then be reset until the next change  
in status is detected.  
The interrupt sources are grouped into three categories: packet handler, chip status, and modem. The individual  
interrupts in these groups can be enabled/disabled in the interrupt property registers, 0x0101, 0x0102, and 0x0103.  
An interrupt must be enabled for it to trigger an event on the nIRQ pin. The interrupt group must be enabled as well  
as the individual interrupts in API property 0x0100.  
Once an interrupt event occurs and the nIRQ pin is low the interrupts are read and cleared using the  
GET_INT_STATUS command. By default all interrupts will be cleared once read. The instantaneous status of a  
specific function may be read if the specific interrupt is enabled or disabled. The status results are provided after  
the interrupts and can be read with the same commands as the interrupts. The status bits will give the current state  
of the function whether the interrupt is enabled or not.  
5.5. GPIO  
Four General Purpose IO (GPIO) pins are available for use in the application. The GPIOs are configured using the  
GPIO_PIN_CFG command. GPIO pins 0 and 1 should be used for active signals such as data or clock. GPIO pins  
2 and 3 have more susceptibility to generating spurious components in the synthesizer than pins 0 and 1. The drive  
strength of the GPIOs can be adjusted with the GEN_CONFIG parameter in the GPIO_PIN_CFG command. By  
default, the drive strength is set to the minimum. The default configuration and the state of the GPIO during  
shutdown are shown in Table 14. For a complete list of the GPIO options, please refer to the API guide application  
note, “AN691: EZRadio API Guide”.  
Table 14. GPIOs  
Pin  
SDN State  
POR Default  
POR  
GPIO0  
GPIO1  
GPIO2  
GPIO3  
nIRQ  
0
0
0
0
CTS  
POR  
POR  
Resistive V pull-up  
nIRQ  
SDO  
DD  
SDO  
Resistive V pull-up  
DD  
SDI  
High Z  
SDI  
Rev 1.0  
25  
Si4355  
6. Data Handling and Packet Handler  
6.1. RX FIFO  
A 64-byte RX FIFO is integrated into the chip. Reading from command register 77h reads data from this RX FIFO.  
6.2. Packet Handler  
The Si4355 includes integrated packet handler features such as preamble and sync word detection as well as CRC  
calculation. This allows the chip to qualify and synchronize with legitimate transmissions independent of the  
microcontroller. These features can be enabled using the EZConfig setup. In this setup, the preamble and sync  
word length can be modified and the sync word pattern can be selected. The general packet structure is shown in  
Figure 12.  
There is also the option within the EZConfig setup to select a variable packet length. With this setting, the receiver  
is not required to know the packet length ahead of time. The transmitter sends the length of the packet immediately  
after the sync word. The packet structure for variable length packets is shown in Figure 13.  
Preamble  
Sync Word  
1 – 4 Bytes  
Data  
CRC  
0 – 255 Bytes  
1 – 64 Bytes  
2 Bytes  
Figure 12. Packet Structure for Fixed Packet Length  
Preamble  
Sync Word  
1 – 4 Bytes  
Length  
1 Byte  
Data  
CRC  
0 – 255 Bytes  
1 – 64 Bytes  
2 Bytes  
Figure 13. Packet Structure for Variable Packet Length  
26  
Rev 1.0  
Si4355  
7. Pin Descriptions  
GND  
1
2
3
4
5
6
20 19 18 17 16 nSEL  
15 SDI  
SDN  
RXp  
RXn  
NC  
14 SDO  
13 SCLK  
12 nIRQ  
GND  
7
8
9
10 11 GPIO1  
Pin  
Pin Name  
I/O  
Description  
Ground  
1
GND  
GND  
I
Shutdown (0 – V V) – SDN = 1, part will be in shutdown mode and contents  
of all registers are lost. SDN = 0, all other modes.  
DD  
2
SDN  
Differential RF receiver input pin  
3
4
RXp  
RXn  
NC  
I
I
Differential RF receiver input pin  
No Connect  
5
Ground  
6
GND  
GND  
Supply voltage  
7
V
V
V
V
DD  
DD  
DD  
DD  
Supply voltage  
8
Ground  
9
GND  
GND  
I/O  
General Purpose Digital I/O  
General Purpose Digital I/O  
10  
11  
GPIO0  
GPIO1  
I/O  
Interrupt Status Output – nIRQ = 0, interrupt event has occurred. Read interrupt  
status for event details.  
12  
13  
nIRQ  
O
I
Serial Clock Input (0 – V V)—Provides serial data clock for 4-line serial data  
DD  
SCLK  
bus.  
Serial Data Output (0 – V V)— Provides serial data readback function of  
internal control registers.  
DD  
14  
15  
SDO  
SDI  
O
I
Serial Data Input (0 – V V)—Serial data stream input for 4-line serial data bus  
DD  
Rev 1.0  
27  
Si4355  
Pin  
Pin Name  
I/O  
Description  
Serial Interface Select Input (0 – V V) – Provides select/enable function for  
4-line serial data bus  
DD  
16  
nSEL  
I
Crystal Oscillator Output  
17  
18  
19  
20  
XOUT  
XIN  
O
I
Crystal Oscillator Input—No DC bias required, but if used, should be set to 7 V.  
General Purpose Digital I/O  
GPIO2  
GPIO3  
I/O  
I/O  
General Purpose Digital I/O  
28  
Rev 1.0  
Si4355  
8. Ordering Information  
*
Description  
Package Type  
Operating  
Temperature  
Part Number  
Si4355-B1A-FM  
EZRadio Receiver  
3x3 QFN-20  
Pb-free  
–40 to 85 °C  
*Note: Add an “R” at the end of the device part number to denote tape and reel option.  
Rev 1.0  
29  
Si4355  
9. Package Outline  
Figure 14. 20-pin QFN Package  
30  
Rev 1.0  
Si4355  
Table 15. Package Diagram Dimensions  
Dimension  
Min  
0.80  
0.00  
Nom  
0.85  
Max  
0.90  
0.05  
A
A1  
A3  
b
0.02  
0.20 REF  
0.25  
0.18  
0.25  
0.30  
0.35  
c
0.30  
D
3.00 BSC.  
1.70  
D2  
e
1.55  
1.85  
0.50 BSC.  
3.00 BSC.  
1.70  
E
E2  
f
1.55  
0.30  
1.85  
0.50  
2.40 BSC.  
0.40  
L
aaa  
bbb  
ccc  
ddd  
eee  
fff  
0.15  
0.10  
0.10  
0.05  
0.08  
0.10  
Note: All dimensions shown are in millimeters (mm) unless otherwise noted.  
Rev 1.0  
31  
Si4355  
10. PCB Land Pattern  
Figure 15. 20-pin QFN PCB Land Pattern  
Table 16. PCB Land Pattern Dimensions  
Dimension  
C1  
Min  
Max  
3.00  
3.00  
C2  
E
0.50 REF  
X1  
X2  
Y1  
Y2  
Y3  
f
0.25  
1.65  
0.85  
1.65  
0.37  
0.35  
1.75  
0.95  
1.75  
0.47  
2.40 REF  
c
0.25  
0.35  
Note: : All dimensions shown are in millimeters (mm) unless otherwise noted.  
32  
Rev 1.0  
Si4355  
11. Top Marking  
11.1. Si4355 Top Marking  
Figure 16. Si4355 Top Marking  
11.2. Top Marking Explanation  
Mark Method:  
Laser  
Line 1 Marking:  
Part Number  
4355A  
Firmware Revision  
Die Revision  
Line 2 Marking:  
Line 3 Marking:  
Internal tracking number  
TTTT = Trace Code  
Circle = 0.5 mm Diameter  
(Bottom-Left Justified)  
Y = Year  
WW = Workweek  
Assigned by the Assembly House. Corresponds to the last  
significant digit of the year and work week of the mold date.  
Rev 1.0  
33  
Si4355  
CONTACT INFORMATION  
Silicon Laboratories Inc.  
400 West Cesar Chavez  
Austin, TX 78701  
Tel: 1+(512) 416-8500  
Fax: 1+(512) 416-9669  
Toll Free: 1+(877) 444-3032  
Please visit the Silicon Labs Technical Support web page:  
https://www.silabs.com/support/pages/contacttechnicalsupport.aspx  
and register to submit a technical support request.  
The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice.  
Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from  
the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features  
or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, rep-  
resentation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability  
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation conse-  
quential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to  
support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where per-  
sonal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized ap-  
plication, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages.  
Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc.  
Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders.  
34  
Rev 1.0  

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