SI4438-C
High-Performance, Low-Current TransceiverThe SI4438-C is a high-performance, low-current transceiver from Silicon Labs. View the full SI4438-C datasheet below including key specifications, electrical characteristics, absolute maximum ratings.
SI4438-C shares its datasheet with SI4438-C2A-GM, whose page lists every part number it covers.
Official SI4438-C datasheet (PDF) — the source this page was extracted from.
SI4438-C Key Specifications
| Parameter | Value |
|---|---|
| Data Rate | 100 bps to 500 kbps |
| FIFO Size | 64 byte TX and RX FIFOs |
| Interface | SPI |
| Modulation | (G)FSK, OOK |
| RX Current | 13.7 mA |
| TX Current | 75 mA at +20 dBm, 490 MHz, 3.3 V |
| Link Budget | 144 dB |
| Supply Voltage | 1.8V to 3.8V |
| Frequency Range | 425 MHz to 525 MHz |
| Standby Current | 40 nA |
| Max Output Power | +20 dBm |
| Shutdown Current | 30 nA |
| Package Dimensions | 4x4 mm |
| Receive Sensitivity | -124 dBm |
| RX Channel Bandwidth | 1.1 kHz to 850 kHz |
| Operating Temperature | -40°C to 85°C |
| Preamble Sense Mode Current | 6 mA average at 1.2 kbps |
SI4438-C Overview
Part: Si4438-C2A-GMR — Silicon Laboratories
Type: Sub-GHz ISM Transceiver (EZRadioPRO family)
Description: 425–525 MHz, 1.8–3.8 V (G)FSK/OOK transceiver with up to +20 dBm output power, -124 dBm receive sensitivity, and 13.7 mA RX current, targeted at China smart meters.
Operating Conditions:
- Supply voltage: 1.8–3.8 V (3.3 V typ)
- Operating temperature: -40 to +85 °C (ambient)
- Frequency range: 425–525 MHz
- Data rate: 0.1–500 kbps (G)FSK, 0.1–120 kbps OOK
Absolute Maximum Ratings:
- VDD to GND: -0.3 to +3.8 V
- Instantaneous voltage on TX output pin (RF-peak to GND): -0.3 to +8.0 V
- Sustained voltage on TX output pin (RF-peak to GND): -0.3 to +6.5 V
- Voltage on digital control inputs and analog inputs: -0.3 to VDD + 0.3 V
- Voltage on XIN when using a TCXO: -0.7 to VDD + 0.3 V
- RX input power: +10 dBm
- Storage temperature: -55 to +150 °C
- Max junction temperature (TJMAX): +105 °C (Thermal Operating Characteristics table)
Key Specs:
- RX current: 13.7 mA typ; TX current: 75 mA typ at +20 dBm, class-E match, 490 MHz, 3.3 V
- Shutdown current: 30 nA typ; standby: 40 nA typ; sleep (RC oscillator on): 740 nA typ
- Preamble sense mode current: 6 mA at 1.2 kbps; 10 μA with 1 s wake interval at 50 kbps
- RX sensitivity (BER < 0.1%, GFSK): -124 dBm at 500 bps; -114 dBm at 9.6 kbps; -108 dBm at 40 kbps; -104 dBm at 100 kbps
- OOK sensitivity: -108 dBm at 4.8 kbps
- TX output power range: -20 to +20 dBm (3.3 V, class-E match)
- Blocking: -77 dB at 1 MHz offset; -84 dB at 8 MHz offset
- Synthesizer lock time: 50 μs typ; phase noise -109 dBc/Hz at 10 kHz offset, 460 MHz
- Crystal range: 25–32 MHz; 30 MHz XTAL start-up 300 μs typ
- Thermal impedance θJA: 25 °C/W
Features:
- Frequency range 425–525 MHz
- (G)FSK and OOK modulation
- Link budget of 144 dB
- 58 dB adjacent channel selectivity, 75 dB blocking at 1 MHz
- Preamble Sense Mode
- Antenna diversity and T/R switch control
- Configurable packet handler with 64-byte TX and RX FIFOs
- Auto frequency control (AFC) and automatic gain control (AGC)
- Low battery detector and temperature sensor
- IEEE 802.15.4g ready
- Suitable for China regulatory (State Grid)
- Footprint- and pin-compatible with Si446x radios
Applications:
- China smart meters (especially electric meters)
Package:
- 20-pin QFN
SI4438-C 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
SI4438-C Pin Configuration
| Pin | Pin Name | I/0 | Description |
|---|---|---|---|
| 1 | SDN | I | Shutdown Input Pin . 0-VDD V digital input. SDNshould 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. |
| 2 | RXp | I | Differential RF Input Pins of the LNA. See application schematic for example matching network. |
| 3 | RXn | I | Differential RF Input Pins of the LNA. See application schematic for example matching network. |
| 4 | TX | O | Transmit Output Pin. The PA output is an open-drain connection, so the L-C match must supply VDD (+3.3 VDC nominal) to this pin. |
| 5 | NC | It is recommended to connect this pin to GND per the reference design schematic. Not connected internally to any circuitry. | |
| 6 | VDD | VDD | +1.8 to +3.8 V Supply Voltage Input to Internal Regulators. The recommended VDD supply voltage is +3.3 V. |
| 7 | TXRAMP | O | Programmable Bias Output with Ramp Capability for External FET PA. See "5.4. Transmitter (TX)" on page 27. |
| 8 | VDD | VDD | +1.8 to +3.8 V Supply Voltage Input to Internal Regulators. The recommended VDD supply voltage is +3.3 V. |
| 9 | GPIO0 | I/O | General Purpose Digital I/O. May be configured through the registers to perform various functions including: Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, AntDiversity control, etc. |
| 10 | GPIO1 | I/O | General Purpose Digital I/O. May be configured through the registers to perform various functions including: Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, AntDiversity control, etc. |
| Pin | Pin Name | I/0 | Description |
| 11 | nIRQ | O | General Microcontroller Interrupt Status Output. When the Si4438 exhibits any one of the interrupt events, the nIRQ pin will be 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. |
| 12 | SCLK | I | Serial Clock Input. 0-VDD V digital input. This pin provides the serial data clock function for the 4-line serial data bus. Data is clocked into the Si4438 on positive edge transi- tions. |
| 13 | SDO | O | 0-VDD V Digital Output. Provides a serial readback function of the internal control registers. |
| 14 | SDI | I | Serial Data Input. 0-VDD V digital input. This pin provides the serial data stream for the 4-line serial data bus. |
| 15 | nSEL | I | Serial Interface Select Input. 0-VDD V digital input. This pin provides the Select/Enable function for the 4-line serial data bus. |
| 16 | XOUT | O | Crystal Oscillator Output. Connect to an external 25 to 32 MHz crystal, or leave floating when driving with an external source on XIN. |
| 17 | XIN | I | Crystal Oscillator Input. Connect to an external 25 to 32 MHz crystal, or connect to an external source. |
| 18 | GND | GND | When using a XTAL, leave floating per the reference design schematic. When using a TCXO, connect to TCXO GND which should be separate from the board reference ground plane. |
| 19 | GPIO2 | I/O | General Purpose Digital I/O. May be configured through the registers to perform various functions, including Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery |
| 20 | GPIO3 | I/O | Detect, TRSW, AntDiversity control, etc. |
| PKG | PADDLE_GND | GND | The exposed metal paddle on the bottom of the Si4438 supplies the RF and circuit ground(s) for the entire chip. It is very important that a good solder con- nection is made between this exposed metal paddle and the ground plane of the PCB underlying the Si4438. |
SI4438-C Electrical Characteristics
Table 1. DC Characteristics *
| Parameter | Symbol | Test Condition | Min | Typ | Max | Unit |
|---|---|---|---|---|---|---|
| Supply Voltage Range | V DD | 1.8 | 3.3 | 3.8 | V | |
| Power Saving Modes | I Shutdown | RC Oscillator, Main Digital Regulator, and Low Power Digital Regulator OFF | - | 30 | - | nA |
| Power Saving Modes | I Standby | Register values maintained and RC oscillator/WUT OFF | - | 40 | - | nA |
| Power Saving Modes | I SleepRC | RC Oscillator/WUT ON and all register values maintained, and all other blocks OFF | - | 740 | - | nA |
| Power Saving Modes | I SleepXO | Sleep current using an external 32 kHz crystal. | - | 1.7 | - | μ A |
| Power Saving Modes | I Sensor -LBD | Low battery detector ON, register values main- tained, and all other blocks OFF | - | 1 | - | μ A |
| Power Saving Modes | I Ready | Crystal Oscillator and Main Digital Regulator ON, all other blocks OFF | - | 1.8 | - | mA |
| Preamble Sense Mode Current | I psm | Duty cycling during preamble search, 1.2 kbps, 4 byte preamble | - | 6 | - | mA |
| Preamble Sense Mode Current | I psm | Fixed 1 s wakeup interval, 50 kbps, 5 byte pream- ble | - | 10 | - | μ A |
| TUNE Mode Current | I Tune_RX | RX Tune | - | 7.6 | - | mA |
| TUNE Mode Current | I Tune_TX | TX Tune | - | 7.8 | - | mA |
| RX Mode Current | I RXH | - | 13.7 | - | mA | |
| TX Mode Current (Si4438) | I TX_+20 | +20 dBm output power, class-E match, 490 MHz, 3.3 V | - | 75 | - | 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.
**Table 1. DC Characteristics ***
Table 2. Synthesizer AC Electrical Characteristics 1
| Parameter | Symbol | Test Condition | Min | Typ | Max | Unit |
|---|---|---|---|---|---|---|
| Synthesizer Frequency Range (Si4438) | F SYN | 425 | - | 525 | MHz | |
| Synthesizer Frequency Resolution 2 | F RES-525 | 425-525 MHz | - | 14.3 | - | Hz |
| Synthesizer Settling Time | t LOCK | Measured from exiting Ready mode with XOSC running to any frequency. Including VCO Calibration. | - | 50 | - | μ s |
| Phase Noise | L (f M ) | F = 10 kHz, 460 MHz | - | -109 | - | dBc/Hz |
| Phase Noise | L (f M ) | F = 100 kHz, 460 MHz | - | -111 | - | dBc/Hz |
| Phase Noise | L (f M ) | F = 1 MHz, 460 MHz | - | -131 | - | dBc/Hz |
| Phase Noise | L (f M ) | F = 10 MHz, 460 MHz | - | -141 | - | dBc/Hz |
-
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.
-
Default API setting for modulation deviation resolution is double the typical value specified.
SI4438-C Absolute Maximum Ratings
| Parameter | Value | Unit |
|---|---|---|
| V DD to GND | -0.3, +3.8 | V |
| Instantaneous V to GND on TX Output Pin | RF-peak -0.3, +8.0 | V |
| Sustained V to GND | RF-peak on TX Output Pin -0.3, +6.5 | V |
| Voltage on Digital | Control Inputs -0.3, V DD + 0.3 | V |
| Voltage on Analog Inputs | -0.3, V DD + 0.3 | V |
| Voltage on XIN Input when | using a TCXO -0.7, V DD + 0.3 | V |
| RX Input Power | +10 | dBm |
*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. Power Amplifier may be damaged if switched on without proper load or termination connected. TX matching network design will influence TX V RF-peak on TX output pin. Caution: ESD sensitive device.
SI4438-C Thermal Information
| Parameter | Value | Unit |
|---|---|---|
| Operating Ambient Temperature Range T A | -40 to +85 | C |
| Thermal Impedance JA | 25 | C / W |
| Junction Temperature T JMAX | +105 | C |
| Storage Temperature Range T STG | -55 to +150 | C |
SI4438-C Package Information
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 | Min | Nom | Max |
|---|---|---|---|
| A | 0.80 | 0.85 | 0.90 |
| A1 | 0.00 | 0.02 | 0.05 |
| A3 | 0.20 REF | 0.20 REF | 0.20 REF |
| b | 0.18 | 0.25 | 0.30 |
| D | 4.00 BSC | 4.00 BSC | 4.00 BSC |
| D2 | 2.45 | 2.60 | 2.75 |
| e | 0.50 BSC | 0.50 BSC | 0.50 BSC |
| E | 4.00 BSC | 4.00 BSC | 4.00 BSC |
| E2 | 2.45 | 2.60 | 2.75 |
| L | 0.30 | 0.40 | 0.50 |
| aaa | 0.15 | 0.15 | 0.15 |
| bbb | 0.15 | 0.15 | 0.15 |
| ccc | 0.10 | 0.10 | 0.10 |
| ddd | 0.10 | 0.10 | 0.10 |
| eee | 0.08 | 0.08 | 0.08 |
- All dimensions are shown in millimeters (mm) unless otherwise noted.
- Dimensioning and tolerancing per ANSI Y14.5M-1994.
- This drawing conforms to the JEDEC Solid State Outline MO-220, Variation VGGD-8.
- Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components.
Variants on the same datasheet
These parts have exact links to the same datasheet. They are candidates to compare, not verified drop-in replacements; check package, pinout and electrical limits.
| Part Number | Manufacturer | Package |
|---|---|---|
| SI4438 | Silicon Labs | QFN-20 |
| SI4438-C2A-GM | Silicon Labs | QFN-20 Pb-free |
| SI4438-C2A-GMR | Silicon Labs | QFN-20 |
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