SI4438-C2A-GMR

High-Performance, Low-Current Transceiver

The SI4438-C2A-GMR is a high-performance, low-current transceiver from Silicon Laboratories. View the full SI4438-C2A-GMR datasheet below including key specifications, pinout, electrical characteristics, absolute maximum ratings.

Manufacturer

Silicon Laboratories

Key Specifications

Parameter	Value
Data Rate	100 bps to 500 kbps
RX Current	13.7 mA
TX Current	75 mA @+20 dBm
Frequency Range	425 to 525 MHz
Standby Current	40 nA
TX/RX FIFO Size	64 byte
Max Output Power	+20 dBm
Modulation Types	(G)FSK, OOK
Shutdown Current	30 nA
Receive Sensitivity	-124 dBm
Supply Voltage Range	1.8 to 3.8 V
Communication Interface	SPI
Operating Temperature Range	-40 to +85 °C

Overview

Part: Si4438 — Silicon Laboratories Type: High-Performance, Low-Current Transceiver Description: The Si4438 is a high-performance, low-current sub-GHz transceiver operating in the 425-525 MHz frequency range, offering -124 dBm receive sensitivity and up to +20 dBm output power, targeted at China smart meter applications.

Operating Conditions:

Supply voltage: 1.8–3.8 V
Operating temperature: -40 to +85 °C
Frequency range: 425–525 MHz

Absolute Maximum Ratings:

Max supply voltage: 3.8 V
Max RX input power: +10 dBm
Max junction temperature: +105 °C
Max storage temperature: -55 to +150 °C

Key Specs:

Receive sensitivity: -124 dBm (BER < 0.1%, 500 bps, GFSK, BT = 0.5, f = 250Hz)
Max output power: +20 dBm
RX mode current: 13.7 mA
TX mode current: 75 mA (+20 dBm output power, class-E match, 490 MHz, 3.3 V)
Shutdown current: 30 nA
Standby current: 40 nA
Data rate (GFSK): 0.1 to 500 kbps
Data rate (OOK): 0.1 to 120 kbps
Adjacent channel selectivity: -60 dB (1-Ch Offset, 450 MHz)

Features:

Modulation: (G)FSK, OOK
Preamble Sense Mode
Fast wake and hop times
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
IEEE 802.15.4g ready
Suitable for China regulatory (State Grid)

Applications:

China smart meters
Electric meters

Package:

20-Pin QFN package

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

Pin Configuration

SI4438-C2A-GMR Pinout

Package: QFN-20 (with exposed paddle)

Pin	Pin Name	Type	Description
1	SDN	I	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 register contents will be lost.
2	RXp	I	Differential RF Input Pin of the LNA. See application schematic for example matching network.
3	RXn	I	Differential RF Input Pin of the LNA. See application schematic for example matching network.
4	TX	O	Transmit Output Pin. The PA output is an open-drain connection; the L-C match must supply VDD (+3.3 VDC nominal) to this pin.
5	NC	—	No Connect. Recommended to connect to GND per reference design schematic. Not connected internally to any circuitry.
6	VDD	P	+1.8 to +3.8 V Supply Voltage Input to Internal Regulators. Recommended VDD = +3.3 V.
7	TXRAMP	O	Programmable Bias Output with Ramp Capability for External FET PA.
8	VDD	P	+1.8 to +3.8 V Supply Voltage Input to Internal Regulators. Recommended VDD = +3.3 V.
9	GPIO0	I/O	General Purpose Digital I/O. Configurable for Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, Ant Diversity control, etc.
10	GPIO1	I/O	General Purpose Digital I/O. Configurable for Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, Ant Diversity control, etc.
11	nIRQ	O	General Microcontroller Interrupt Status Output. Set low (0) when Si4438 exhibits any interrupt event. No external pull-up resistor required, but may be desirable if multiple interrupt lines are connected.
12	SCLK	I	Serial Clock Input. 0-VDD V digital input. Provides serial data clock function for 4-line serial data bus. Data clocked in on positive edge transitions.
13	SDO	O	0-VDD V Digital Output. Provides serial readback function of internal control registers.
14	SDI	I	Serial Data Input. 0-VDD V digital input. Provides serial data stream for 4-line serial data bus.
15	nSEL	I	Serial Interface Select Input. 0-VDD V digital input. Provides Select/Enable function for 4-line serial data bus.
16	XOUT	O	Crystal Oscillator Output. Connect to external 25–32 MHz crystal, or leave floating when driving with external source on XIN.
17	XIN	I	Crystal Oscillator Input. Connect to external 25–32 MHz crystal, or connect to external source.
18	GND	S	Ground. Leave floating when using XTAL per reference design. When using TCXO, connect to TCXO GND (separate from board reference ground plane).
19	GPIO2	I/O	General Purpose Digital I/O. Configurable for Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, Ant Diversity control, etc.
20	GPIO3	I/O	General Purpose Digital I/O. Configurable for Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW, Ant Diversity control, etc.
PKG	PADDLE_GND	S	Exposed metal paddle on bottom of package. Supplies RF and circuit ground(s) for entire chip. Critical to make good solder connection between paddle and PCB ground plane.

Notes

Pin 5 (NC) is recommended to be connected to GND per reference design, though not internally connected.
Pins 6 and 8 are both VDD supply inputs; both should be properly decoupled.
Pin 18 (GND) handling depends on oscillator type: leave floating for crystal, connect to separate TCXO ground for TCXO.
The exposed paddle (PADDLE_GND) is essential for RF and circuit grounding and must have good solder connection to PCB ground plane.
GPIO0, GPIO1, GPIO2, GPIO3 are highly configurable and can be assigned to multiple functions via register configuration.

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.

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.

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

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.

Ordering Information

Part Number	Description	Package Type	Operating Temperature	Packing
Si4438-C2A-GM	ISM EZRadioPRO Transceiver	QFN-20 Pb-free	-40 to 85 °C	Tray/Tube
Si4438-C2A-GMR	ISM EZRadioPRO Transceiver	QFN-20 Pb-free	-40 to 85 °C	Tape and Reel

Related Variants

The following components are covered by the same datasheet.

Part Number	Manufacturer	Package
SI4438	Silicon Laboratories	—
SI4438-C	Silicon Laboratories	—
SI4438-C2A-GM	Silicon Laboratories	QFN-20 Pb-free

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