Silicon Laboratories Si4438-C Manual
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Silicon Laboratories Si4438-C Manual

High-performance, low-current transceiver
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H
-P
I G H
E R F O R M A N C E
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, 40 nA standby

Data rate = 100 bps to 500 kbps
Preamble Sense Mode
6 mA average Rx current at

1.2 kbps
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
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
Arrow.com.
Downloaded from
, L
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
Suitable for China regulatory (State
Grid)
®
family, which includes a complete line of transmitters,
Copyright © 2014 by Silicon Laboratories
-C
O W
U R R E N T
S i 4 4 3 8 - C
T
R A N SC E I V E R
Pin Assignments
Patents pending
Si4438-C

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  • Page 1 Applications China smart meters  Description Silicon Laboratories' Si4438 is a high-performance, low-current Patents pending 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.
  • Page 2 Si 4 4 3 8 -C Functional Block Diagram Product Freq. Range Max Output TX Current RX Current Power Si4438 425–525 MHz +20 dBm 75 mA 13.7 mA Rev 1.0 Arrow.com. Arrow.com. Downloaded from Downloaded from...

  • Page 3: Table Of Contents

    9. Pin Descriptions: Si4438-C ........

  • Page 4: Electrical Specifications

    Si 4 4 3 8 -C 1. Electrical Specifications Table 1. DC Characteristics Parameter Symbol Test Condition Unit Supply Voltage Range Power Saving Modes RC Oscillator, Main Digital Regulator, — — Shutdown and Low Power Digital Regulator OFF Register values maintained and RC —...
  • Page 5 Si 44 38 -C 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 Si 4 4 3 8 -C 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 <...
  • Page 7 Si 44 38 -C 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 —...
  • Page 8 Si 4 4 3 8 -C 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 Si 44 38 -C 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 Si 4 4 3 8 -C Table 7. Thermal Operating Characteristics Parameter Value Unit Operating Ambient Temperature Range T C –40 to +85 Thermal Impedance  C/W Junction Temperature T C +105 JMAX Storage Temperature Range T C –55 to +150 Table 8.

  • Page 11: Functional Description

    Si 44 38 -C 2. Functional Description The Si4438 devices are high-performance, low-current, wireless ISM transceivers that cover the sub-GHz bands. The wide operating voltage range of 1.8–3.8 V and low current consumption make the Si4438 an ideal solution for battery powered applications.

  • Page 12: Controller Interface

    Si 4 4 3 8 -C 3. Controller Interface 3.1. Serial Peripheral Interface (SPI) The Si4438 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 demonstrated in Table 9.
  • Page 13 Si 44 38 -C Figure 2. SPI Read Command—Check CTS Value Figure 3. SPI Read Command—Clock Out Read Data Rev 1.0 Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Arrow.com. Downloaded from Downloaded from Downloaded from Downloaded from Downloaded from Downloaded from...

  • Page 14: Fast Response Registers

    Si 4 4 3 8 -C 3.2. Fast Response Registers The fast response registers are registers that can be read immediately without the requirement to monitor and check CTS. There are four fast response registers that can be programmed for a specific function. The fast response registers can be read through API commands, 0x50 for Fast Response A, 0x51 for Fast Response B, 0x53 for Fast Response C, and 0x57 for Fast Response D.
  • Page 15 Si 44 38 -C 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 504 μs 516 μs 40 nA Sleep State 504 μs 516 μs 740 nA SPI Active State...
  • Page 16 Si 4 4 3 8 -C 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 Si 44 38 -C 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.

  • Page 18: Application Programming Interface

    Si 4 4 3 8 -C 3.4. Application Programming Interface The host MCU communicates with an application programming interface (API) embedded inside the device. The API is divided into two sections, commands and properties. The commands are used to control the chip and retrieve its status.

  • Page 19: Modulation And Hardware Configuration Options

    Si 44 38 -C 4. Modulation and Hardware Configuration Options The Si4438 supports three different modulation options and can be used in various configurations to tailor the device to any specific application or legacy system for drop in replacement. The modulation and configuration options are set in property, MODEM_MOD_TYPE.
  • Page 20 Si 4 4 3 8 -C 4.2.2.1. FIFO Mode In FIFO mode, the transmit and receive data is stored in integrated FIFO register memory. The TX FIFO is accessed by writing Command 66h followed directly by the data/clk that the host wants to write into the TX FIFO. The RX FIFO is accessed by writing command 77h followed by the number of clock cycles of data the host would like to read out of the RX FIFO.

  • Page 21: Preamble Length

    Si 44 38 -C 4.3. Preamble Length 4.3.1. Digital Signal Arrival Detector Traditional preamble detection requires 20 bits to detect preamble. This device introduces a new approach to signal detection that can detect a preamble pattern in as little as one byte. If AFC is enabled, a preamble length of two bytes is sufficient to reliably detect signal arrival and settle a one shot AFC.
  • Page 22 Si 4 4 3 8 -C Table 13. Recommended Preamble Length Antenna Recommended Recommended Preamble Mode Preamble Type Diversity Preamble Length 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...

  • Page 23: Internal Functional Blocks

    Si 44 38 -C 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 24 Si 4 4 3 8 -C 5.2.2. Auto Frequency Correction (AFC) Frequency mistuning caused by crystal inaccuracies can be compensated for by enabling the digital automatic frequency control (AFC) in receive mode. There are two types of integrated frequency compensation: modem frequency compensation, and AFC by adjusting the PLL frequency.

  • Page 25: Synthesizer

    Si 44 38 -C 5.2.4. RSSI Jump Indicator (Collision Detection) The chip is capable of detecting a jump in RSSI in either direction (i.e., either a signal increase or a signal decrease). Both polarities of jump detection may be enabled simultaneously, resulting in detection of a Jump-Up or Jump-Down event.
  • Page 26 Si 4 4 3 8 -C 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 27: Transmitter (Tx)

    Si 44 38 -C 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 28 Si 4 4 3 8 -C Number Command Summary 0x2200 PA_MODE Sets PA type. 0x2201 PA_PWR_LVL Adjust TX power in fine steps. Adjust TX power in coarse steps and opti- 0x2202 PA_BIAS_CLKDUTY mizes for different match configurations. 0x2203 PA_TC Changes the ramp up/down time of the PA. 5.4.1.

  • Page 29: Crystal Oscillator

    Si 44 38 -C TX Power vs Temp 20.5 19.5 18.5 -40 -30 -20 -10 Temperature (C) Figure 9. +20 dBm TX Power vs. Temp 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.
  • Page 30 Si 4 4 3 8 -C can be canceled. A TCXO or external signal source can easily be used in place of a conventional XTAL and should be connected to the XIN pin. The incoming clock signal is recommended to be peak-to-peak swing in the range of 600 mV to 1.4 V and ac-coupled to the XIN pin.

  • Page 31: Data Handling And Packet Handler

    Si 44 38 -C 6. Data Handling and Packet Handler 6.1. RX and TX FIFOs Two 64-byte FIFOs are integrated into the chip, one for RX and one for TX, as shown in Figure 11. Writing to command Register 66h loads data into the TX FIFO, and reading from command Register 77h reads data from the RX FIFO.

  • Page 32: Packet Handler

    Si 4 4 3 8 -C 6.2. Packet Handler When using the FIFOs, automatic packet handling may be enabled for TX mode, RX mode, or both. The usual fields for network communication, such as preamble, synchronization word, headers, packet length, and CRC, can be configured to be automatically added to the data payload.

  • Page 33: Rx Modem Configuration

    Si 44 38 -C 7. RX Modem Configuration The Si4438 can easily be configured for different data rate, deviation, frequency, etc. by using the WDS settings calculator, which generates an initialization file for use by the host MCU. 8. Auxiliary Blocks 8.1.

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

    Si 4 4 3 8 -C 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 and remains in that mode until the beginning of the next wake-up period.

  • Page 35: Low Battery Detector

    Si 44 38 -C 8.4. Low Battery Detector The low battery detector (LBD) is enabled and utilized as part of the wake-up-timer (WUT). The LBD function is not available unless the WUT is enabled, but the host MCU can manually check the battery voltage anytime with the auxiliary ADC.
  • Page 36 Si 4 4 3 8 -C Table 15. Data Rates* Data Rate 1.2 kbps 9.6 kbps 50 kbps 100 kbps PM length = 4 bytes 6.48 6.84 8.44 10.43 PM length = 8 bytes 3.83 3.96 4.57 5.33 *Note: Typical values. Active RX current is 13 mA. Rev 1.0 Arrow.com.

  • Page 37: Pin Descriptions: Si4438-C

    Si 44 38 -C 9. Pin Descriptions: Si4438-C 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 38 Si 4 4 3 8 -C 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.

  • Page 39: Ordering Information

    Si 44 38 -C 10. Ordering Information Part Number* Description Package Type Operating Temperature Si4438-C2A-GM ISM EZRadioPRO Transceiver QFN-20 –40 to 85 °C Pb-free *Note: Add an “(R)” at the end of the device part number to denote tape and reel option. Rev 1.0 Arrow.com.

  • Page 40: Package Outline: Si4438

    Si 4 4 3 8 -C 11. Package Outline: Si4438 Figure 16 illustrates the package details for the Si4438. Table 16 lists the values for the dimensions shown in the illustration. Figure 16. 20-Pin Quad Flat No-Lead (QFN) Table 16. Package Dimensions Dimension 0.80 0.85...

  • Page 41: Pcb Land Pattern: Si4438

    Si 44 38 -C 12. PCB Land Pattern: Si4438 Figure 17 illustrates the PCB land pattern details for the Si4438. Table 17 lists the values for the dimensions shown in the illustration. Figure 17. PCB Land Pattern Rev 1.0 Arrow.com. Arrow.com.
  • Page 42 Si 4 4 3 8 -C Table 17. 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.

  • Page 43: Top Marking

    Si 44 38 -C 13. Top Marking 13.1. Si4438 Top Marking 13.2. Top Marking Explanation YAG Laser Mark Method Part Number 44382A = Si4438 Rev 2A Line 1 Marking TTTTTT = Internal Code Internal tracking code. Line 2 Marking YY = Year Assigned by the Assembly House.

  • Page 44: Contact Information

    The products must not be used within any Life Support System without the specific written consent of Silicon Laboratories. A "Life Support System" is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected to result in significant personal injury or death.

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