S i4438- C
H
I G H
-P
E R F O R M A N C E
, L
O W
-C
U R R E N T
T
R A N SC E I V E R
Features
Frequency
range = 425–525 MHz
Receive sensitivity = –124 dBm
Modulation
(G)FSK
OOK
Excellent selectivity performance
58
dB adjacent channel
75 dB blocking at 1 MHz
Max output power
+20
dBm
Low active power consumption
14
mA RX
Ultra low current powerdown
modes
30
nA shutdown, 40 nA standby
Data rate = 100 bps to 500 kbps
Preamble Sense Mode
6
mA average Rx current at
1.2 kbps
Antenna diversity and T/R switch
control
Highly configurable packet handler
TX and RX 64 byte FIFOs
Auto frequency control (AFC)
Automatic gain control (AGC)
Low BOM
Low battery detector
Temperature sensor
20-Pin QFN package
IEEE 802.15.4g ready
Suitable for China regulatory (State
Grid)
Pin Assignments
Fast wake and hop times
Power supply = 1.8 to 3.8 V
Applications
China smart meters
Description
Silicon Laboratories' Si4438 is a high-performance, low-current
transceivers covering the sub-GHz frequency bands from 425 to
525 MHz. The Si4438 is targeted at the Chinese smart meter market and
is especially suited for electric meters. This device is footprint- and
pin-compatible with the Si446x radios, which provide industry-leading
performance for worldwide sub-GHz applications. The radios are part of
the EZRadioPRO
®
family, which includes a complete line of transmitters,
receivers, and transceivers covering a wide range of applications. All
parts offer outstanding sensitivity of –124 dBm while achieving extremely
low active and standby current consumption. The 58 dB adjacent channel
selectivity with 12.5 kHz channel spacing ensures robust receive
operation in harsh RF conditions. The Si4438 offers exceptional output
power of up to +20 dBm with outstanding TX efficiency. The high output
power and sensitivity results in an industry-leading link budget of 144 dB
allowing extended ranges and highly robust communication links.
Patents pending
Rev 1.0
Copyright © 2014 by Silicon Laboratories
Si4438-C
Si4438- C
Functional Block Diagram
Product
Si4438
Freq. Range
425–525 MHz
Max Output
Power
+20 dBm
TX Current
75 mA
RX Current
13.7 mA
2
Rev 1.0
Si4438-C
T
A B L E O F
C
O N T E N T S
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3. Controller Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
3.1. Serial Peripheral Interface (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
3.2. Fast Response Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
3.3. Operating Modes and Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
3.4. Application Programming Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
3.5. Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
3.6. GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
4. Modulation and Hardware Configuration Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.1. Modulation Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.2. Hardware Configuration Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.3. Preamble Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5. Internal Functional Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.1. RX Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.2. RX Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.3. Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.4. Transmitter (TX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
5.5. Crystal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6. Data Handling and Packet Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6.1. RX and TX FIFOs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6.2. Packet Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
7. RX Modem Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
8. Auxiliary Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
8.1. Wake-up Timer and 32 kHz Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
8.2. Low Duty Cycle Mode (Auto RX Wake-Up) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
8.3. Temperature, Battery Voltage, and Auxiliary ADC . . . . . . . . . . . . . . . . . . . . . . . . . .34
8.4. Low Battery Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
8.5. Antenna Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
8.6. Preamble Sense Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
9. Pin Descriptions: Si4438-C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
10. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
11. Package Outline: Si4438 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
12. PCB Land Pattern: Si4438 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
13. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
13.1. Si4438 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
13.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Rev 1.0
3
Si4438- C
1. Electrical Specifications
Table 1. DC Characteristics
*
Parameter
Supply Voltage
Range
Power Saving Modes
Symbol
V
DD
I
Shutdown
I
Standby
I
SleepRC
I
SleepXO
I
Sensor -LBD
I
Ready
Preamble Sense
Mode Current
I
psm
I
psm
TUNE Mode Current
RX Mode Current
TX Mode Current
(Si4438)
I
Tune_RX
I
Tune_TX
I
RXH
I
TX_+20
+20 dBm output power, class-E match, 490 MHz,
3.3 V
RC Oscillator, Main Digital Regulator,
and Low Power Digital Regulator OFF
Register values maintained and RC
oscillator/WUT OFF
RC Oscillator/WUT ON and all register values
maintained, and all other blocks OFF
Sleep current using an external 32 kHz crystal.
Low battery detector ON, register values main-
tained, and all other blocks OFF
Crystal Oscillator and Main Digital Regulator ON,
all other blocks OFF
Duty cycling during preamble search,
1.2 kbps, 4 byte preamble
Fixed 1 s wakeup interval, 50 kbps, 5 byte pream-
ble
RX Tune
TX Tune
Test Condition
Min
1.8
—
—
—
—
—
—
—
—
—
—
—
—
Typ
3.3
30
40
740
1.7
1
1.8
6
10
7.6
7.8
13.7
75
Max
3.8
—
—
—
—
—
—
—
—
—
—
—
—
Unit
V
nA
nA
nA
μA
μA
mA
mA
μA
mA
mA
mA
mA
*Note:
All minimum and maximum values are guaranteed across the recommended operating conditions of supply voltage
and from –40 to +85 °C unless otherwise stated. All typical values apply at VDD = 3.3 V and 25 °C unless otherwise
stated.
4
Rev 1.0
Si4438-C
Table 2. Synthesizer AC Electrical Characteristics
1
Parameter
Synthesizer Frequency
Range (Si4438)
Synthesizer Frequency
Resolution
2
Synthesizer Settling Time
Symbol
F
SYN
F
RES-525
t
LOCK
425–525 MHz
Measured from exiting Ready mode with
XOSC running to any frequency.
Including VCO Calibration.
F
= 10 kHz, 460 MHz
F
= 100 kHz, 460 MHz
F
= 1 MHz, 460 MHz
F
= 10 MHz, 460 MHz
Test Condition
Min
425
—
—
Typ
—
14.3
50
Max
525
—
—
Unit
MHz
Hz
μs
Phase Noise
L(f
M
)
—
—
—
—
–109
–111
–131
–141
—
—
—
—
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
Notes:
1.
All minimum and maximum values are guaranteed across the recommended operating conditions of supply voltage and
from –40 to +85 °C unless otherwise stated. All typical values apply at VDD = 3.3 V and 25 °C unless otherwise stated.
2.
Default API setting for modulation deviation resolution is double the typical value specified.
Rev 1.0
5
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