Silicon Laboratories Si4438 Manual
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Silicon Laboratories Si4438 Manual

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H
- P
I G H
ERFORMANCE
Features
Frequency
range = 425–525 MHz
Receive sensitivity = –124 dBm
Modulation
(G)FSK

OOK

Max output power
+20 dBm

Low active power consumption
14 mA RX

Ultra low current powerdown
modes
30 nA shutdown, 50 nA standby

Data rate = 100 bps to 500 kbps
Fast wake and hop times
Power supply = 1.8 to 3.6 V
Applications
China smart meters
Description
Silicon
Laboratories' Si4438 is
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.
Rev 1.0 6/14
, L
-C
O W
U R R E N T
Excellent selectivity performance
58 dB adjacent channel

75 dB blocking at 1 MHz

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
China regulatory
a high-performance,
Copyright © 2014 by Silicon Laboratories
T
RANSCEIVER
Pin Assignments
SDN
1
RXp
2
RXn
3
TX
4
NC
5
6
low-current
Patents pending
Si4438
20
19
18
17
16
15 nSEL
GND
14
SDI
PAD
13
SDO
12
SCLK
11
nIRQ
7
8
9
10
Si4438

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Summary of Contents for Silicon Laboratories Si4438

  • Page 1 425 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 Patents pending pin-compatible with the Si446x radios, which provide industry-leading performance for worldwide sub-GHz applications.
  • Page 2 Si4438 Functional Block Diagram GPIO3 GPIO2 XOUT Loop PFD / CP Filter 30 MHz XO FBDIV Frac-N Div Bootup TX DIV PKDET PKDET nSEL MODEM FIFO Packet Handler SCLK nIRQ LDOs PowerRamp Cntl Digital Logic 32K LP TXRAMP GPIO0 GPIO1 Product Freq.

  • Page 3: Table Of Contents

    13.1. Si4438 Top Marking ........

  • Page 4: Electrical Specifications

    Si4438 1. Electrical Specifications Table 1. DC Characteristics Parameter Symbol Test Condition Unit Supply Voltage Range Power Saving Modes I RC Oscillator, Main Digital Regulator, — — Shutdown and Low Power Digital Regulator OFF Register values maintained and RC —...
  • Page 5 Si4438 Table 2. Synthesizer AC Electrical Characteristics Parameter Symbol Test Condition Unit Synthesizer Frequency — Range (Si4438) Synthesizer Frequency — 14.3 — 425–525 MHz RES-525 Resolution Measured from exiting Ready mode with — — µs Synthesizer Settling Time LOCK XOSC running to any frequency.
  • Page 6 Si4438 Table 3. Receiver AC Electrical Characteristics Parameter Symbol Test Condition Unit RX Frequency — Range (Si4438) RX Sensitivity (BER < 0.1%) — –124 — RX_0.5 (500 bps, GFSK, BT = 0.5, f = 250Hz) (BER < 0.1%) — –108 —...
  • Page 7 Si4438 Table 4. Transmitter AC Electrical Characteristics Parameter Symbol Test Condition Unit TX Frequency — Range (G)FSK Data Rate — kbps OOK Data Rate — kbps Modulation Deviation f — — 425–525 MHz Range Modulation Deviation 14.3 — — 425–525 MHz...
  • Page 8 Si4438 Table 5. Auxiliary Block Specifications Parameter Symbol Test Condition Unit Temperature Sensor — — Sensitivity Codes/ °C Low Battery Detector — — Resolution Microcontroller Clock Configurable to Fxtal or Fxtal 32.768K — Fxtal Output Frequency Range divided by 2, 3, 7.5, 10, 15, or 30 where Fxtal is the reference XTAL frequency.
  • Page 9 Si4438 Table 6. Digital IO Specifications (GPIO_x, SCLK, SDO, SDI, nSEL, nIRQ, SDN) Parameter Symbol Test Condition Unit Rise Time 0.1 x V to 0.9 x V — — RISE = 10 pF, DRV<1:0> = LL Fall Time 0.9 x V to 0.1 x V...
  • Page 10 Si4438 Table 7. Thermal Operating Characteristics Parameter Value Unit C Operating Ambient Temperature Range T –40 to +85 Thermal Impedance  C/W C Junction Temperature T +125 JMAX C Storage Temperature Range T –55 to +125 Table 8. Absolute Maximum Ratings*...

  • Page 11: Functional Description

    MCUs. An integrated temperature sensor, power-on-reset (POR), and GPIOs further reduce overall system cost and size. The Si4438 is designed to work with an MCU, crystal, and a few passive components to create a very low-cost system.

  • Page 12: Controller Interface

    Figure 1. SPI Write Command The Si4438 contains an internal MCU which controls all the internal functions of the radio. For SPI read commands a typical MCU 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.
  • Page 13 Si4438 Firmware Flow 0xFF Retrieve Send Command Read CTS CTS Value Response 0x00 NSEL ReadCmdBuff Figure 2. SPI Read Command—Check CTS Value NSEL Response Byte 0 Response Byte n Figure 3. SPI Read Command—Clock Out Read Data Rev 1.0...

  • Page 14: Fast Response Registers

    3.3. Operating Modes and Timing The primary states of the Si4438 are shown in Figure 4. The shutdown state completely shuts down the radio to minimize current consumption. Standby/Sleep, SPI Active, Ready, TX Tune, and RX tune are available to optimize the current consumption and response time to RX/TX for a given application.
  • Page 15 Si4438 Table 10. Operating State Response Time and Current Consumption Response Time to Current in State State/Mode /Mode Shutdown State 15 ms 15 ms 30 nA Standby State 440 µs 440 µs 50 nA Sleep State 440 µs 440 µs...
  • Page 16 Si4438 Table 11. POR Timing Variable Description Units High time for VDD to fully settle POR circuit PORH Low time for VDD to enable POR PORL Voltage for successful POR 90%*Vdd Starting Voltage for successful POR Slew rate of VDD for successful POR 3.3.2.
  • Page 17 Si4438 3. Enable PLL. 4. Calibrate VCO/PLL. 5. Wait until PLL settles to required transmit frequency (controlled by an internal timer). 6. Activate power amplifier and wait until power ramping is completed (controlled by an internal timer). 7. Transmit packet.

  • Page 18: Application Programming Interface

    EZRadioPRO API Documentation.zip file available on www.silabs.com. 3.5. Interrupts The Si4438 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 (corresponding to the Interrupt Status bits) occur.

  • Page 19: Modulation And Hardware Configuration Options

    Unlike the Si4432/31 solution for non-standard packet structures, there is no requirement to perform deglitching on the data in the host MCU. Glitch-free data is output from Si4438 devices, and a sample clock for the asynchronous data can also be supplied to the host MCU; so, oversampling or bit clock recovery is not required by the host MCU.

  • Page 20: Preamble Length

    Si4438 In TX mode, if the packet handler is enabled, the data bytes stored in FIFO memory are “packaged” together with other fields and bytes of information to construct the final transmit packet structure. These other potential fields include the Preamble, Sync word, Header, CRC checksum, etc. The configuration of the packet structure in TX mode is determined by the Automatic Packet Handler (if enabled), in conjunction with a variety of Packet Handler properties.
  • Page 21 Si4438 Table 13. Recommended Preamble Length Mode Antenna Preamble Type Recommended Recommended Diversity Preamble Length Preamble Detection Threshold (G)FSK Disabled Disabled Standard 4 Bytes 20 bits (G)FSK Enabled Disabled Standard 5 Bytes 20 bits (G)FSK Disabled Disabled Non-standard 2 Bytes...

  • Page 22: Internal Functional Blocks

    Si4438 5. Internal Functional Blocks The following sections provide an overview to the key internal blocks and features. 5.1. RX 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.
  • Page 23 Si4438 5.2.1. Automatic Gain Control (AGC) The AGC algorithm is implemented digitally using an advanced control loop optimized for fast response time. The AGC occurs within a single bit or in less than 2 µs. Peak detectors at the output of the LNA and PGA allow for optimal adjustment of the LNA gain and PGA gain to optimize IM3, selectivity, and sensitivity performance.

  • Page 24: Synthesizer

    Si4438 The RSSI values and curves may be offset by the MODEM_RSSI_COMP property. The default value of 7’h32 corresponds to no RSSI offset. Setting a value less than 7’h32 corresponds to a negative offset, and a value higher than 7’h32 corresponds to a positive offset. The offset value is in 1 dB steps. For example, setting a value of 7’h3A corresponds to a positive offset of 8 dB.
  • Page 25 Si4438 5.3.1.2. Automatic RX Hopping and Hop Table The transceiver supports an automatic hopping feature that can be fully configured through the API. This is intended for RX hopping where the device has to hop from channel to channel and look for packets. Once the device is put into the RX state, it automatically starts hopping through the hop table if the feature is enabled.

  • Page 26: Transmitter (Tx)

    5.4. Transmitter (TX) The Si4438 contains an integrated +20 dBm transmitter or power amplifier that is capable of transmitting from –20 to +20 dBm. The output power steps are less than 0.25 dB within 6 dB of max power but become larger and more non-linear close to minimum output power.
  • Page 27 PA_TC of the PA. 5.4.1. Si4438: +20 dBm PA The +20 dBm configuration utilizes a class-E matching configuration. Typical performance for output power steps, voltage, and temperature are shown in Figures 7–9. The output power is changed in 128 steps through PA_PWR_LVL API.
  • Page 28 Si4438 TX Power vs Temp 20.5 19.5 18.5 -40 -30 -20 -10 Temperature (C) Figure 9. +20 dBm TX Power vs. Temp Rev 1.0...

  • Page 29: Crystal Oscillator

    Si4438 5.5. Crystal Oscillator The Si4438 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.

  • Page 30: Data Handling And Packet Handler

    TX mode and automatically checking them in RX mode greatly reduces the amount of communication between the microcontroller and Si4438. It also greatly reduces the required computational power of the microcontroller. The general packet structure is shown in Figure 12. Any or all of the fields can be enabled and checked by the internal packet handler.
  • Page 31  Construction of CRC field (if enabled) in TX mode  Data whitening and/or Manchester encoding (if enabled) in TX mode For details on how to configure the packet handler, see “AN626: Packet Handler Operation for Si4438 RFICs”. Rev 1.0...

  • Page 32: Rx Modem Configuration

    It allows low average current polling operation by the Si4438 for which the wake-up timer (WUT) is used. RX and TX LDC operation must be set via the GLOBAL_WUT_CONFIG property when setting up the WUT. The LDC wake-up period is determined by the...
  • Page 33 Si4438 Figure 13. RX and TX LDC Sequences The basic operation of RX LDC mode is shown in Figure 14. The receiver periodically wakes itself up to work on RX_STATE during LDC mode duration. If a valid preamble is not detected, a receive error is detected, or an entire packet is not received, the receiver returns to the WUT state (i.e., ready or sleep) at the end of LDC mode duration...

  • Page 34: Temperature, Battery Voltage, And Auxiliary Adc

    Si4438 8.3. Temperature, Battery Voltage, and Auxiliary ADC The Si4438 family contains an integrated auxiliary ADC for measuring internal battery voltage, an internal temperature sensor, or an external component over a GPIO. The ADC utilizes a SAR architecture and achieves 11-bit resolution.

  • Page 35: Pin Descriptions: Si4438

    Si4438 9. Pin Descriptions: Si4438 15 nSEL SCLK nIRQ Pin Name Description Shutdown Input Pin . 0–VDD V digital input. SDN should be = 0 in all modes except Shutdown mode. When SDN = 1, the chip will be completely shut down, and the contents of the registers will be lost.
  • Page 36 Pin Name Description General Microcontroller Interrupt Status Output. When the Si4438 exhibits any one of the interrupt events, the nIRQ pin will be nIRQ set low = 0. The Microcontroller can then determine the state of the interrupt by reading the interrupt status. No external resistor pull-up is required, but it may be desirable if multiple interrupt lines are connected.

  • Page 37: Ordering Information

    Si4438 10. Ordering Information Description Package Type Operating Part Number Temperature QFN-20 ISM EZRadioPRO Transceiver Si4438-B1C-FM –40 to 85 °C Pb-free Notes: 1. Add an “(R)” at the end of the device part number to denote tape and reel option.

  • Page 38: Package Outline: Si4438

    Si4438 11. Package Outline: Si4438 Figure 15 illustrates the package details for the Si4438. Table 14 lists the values for the dimensions shown in the illustration.   bbb C Pin 1 (Laser) aaa C 20x b ccc C C A B...
  • Page 39 Si4438 Table 14. Package Dimensions Dimension 0.80 0.85 0.90 0.00 0.02 0.05 0.20 REF 0.18 0.25 0.30 4.00 BSC 2.45 2.60 2.75 0.50 BSC 4.00 BSC 2.45 2.60 2.75 0.30 0.40 0.50 0.15 0.15 0.10 0.10 0.08 Notes: 1. All dimensions are shown in millimeters (mm) unless otherwise noted.

  • Page 40: Pcb Land Pattern: Si4438

    Si4438 12. PCB Land Pattern: Si4438 Figure 16 illustrates the PCB land pattern details for the Si4438. Table 15 lists the values for the dimensions shown in the illustration. Figure 16. PCB Land Pattern Rev 1.0...
  • Page 41 Si4438 Table 15. PCB Land Pattern Dimensions Symbol Millimeters 3.90 4.00 3.90 4.00 0.50 REF 0.20 0.30 2.55 2.65 0.65 0.75 2.55 2.65 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This land pattern design is based on IPC-7351 guidelines.

  • Page 42: Top Marking

    13. Top Marking 13.1. Si4438 Top Marking 13.2. Top Marking Explanation YAG Laser Mark Method Part Number 44381C = Si4438 Rev 1C Line 1 Marking TTTTT = Internal Code Internal tracking code. Line 2 Marking YY = Year Assigned by the Assembly House. Corresponds to the last Line 3 Marking significant digit of the year and workweek of the mold date.

  • Page 43: Document Change List

    Si4438 OCUMENT HANGE Revision 0.1 to Revision 1.0  Updated notes in Electrical Specifications tables.  Added Table 7, “Thermal Operating Characteristics,” on page 10.  Updated Table 9, “Serial Interface Timing Parameters,” on page 12.  Updated "3.4. Application Programming Interface"...

  • Page 44: Contact Information

    Silicon Laboratories products are not designed, intended, or authorized for use in applications intend- ed to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where personal injury or death may occur.

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