ST25R3920B - NFC Reader IC, 13.56MHz, ISO 14443A/B | STMicroelectronics
MPN: ST25R3920B β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.85 | $3.85 |
| 10 | $3.47 | $34.70 |
| 100 | $3.08 | $308.00 |
| 500 | $2.77 | $1,385.00 |
| 1,000 | $2.46 | $2,460.00 |
Drop-in alternatives for ST25R3920B β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ST25R3916B
β Drop-Inβ 99,999 In Stock
$2.88 / Unit
View Datasheet βST25R3911B
β Drop-Inπ Reference alternative (not in catalog)
PN5180
β Drop-Inπ Reference alternative (not in catalog)
ST25R3920B Maximum Ratings & Electrical Characteristics
| Operating Frequency | 13.56 MHz |
| Supply Voltage | 2.4 V to 5.5 V |
| Supported Protocols | ISO 14443A/B, ISO 15693, FeliCa |
| Transmitter Output Power | Up to 1.4 W |
| Receiver Sensitivity | -70 dBm |
| Data Rates | 106 kbps to 848 kbps |
| Host Interface | SPI (up to 10 MHz) |
| Operating Temperature | -40C to +85C |
| Package | VQFN-32 (5x5 mm) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| REACH Status | Compliant |
| AEC-Q100 | Not qualified |
| Lead-Free | Yes |
| Halogen-Free | Yes |
ST25R3920B Pin Configuration
| Pin 1 | VCC β Power supply input |
| Pin 2 | GND β Ground |
| Pin 3 | SPI_CLK β SPI clock input |
| Pin 4 | SPI_MOSI β SPI master out slave in |
| Pin 5 | SPI_MISO β SPI master in slave out |
| Pin 6 | SPI_CS β SPI chip select (active low) |
| Pin 7 | IRQ β Interrupt request output |
| Pin 8 | RST β Reset input (active low) |
| Pin 9 | ANT1 β Antenna connection 1 |
| Pin 10 | ANT2 β Antenna connection 2 |
| Pin 11 | VSS β Ground for RF section |
| Pin 12 | VDD_RF β RF power supply |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this digital IC. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
ST25R3920B is suitable for 6 applications: Point-of-Sale Terminals, Access Control Systems, NFC-Enabled Smart Locks, Industrial Asset Tracking, Consumer Electronics, Automotive NFC.
Point-of-Sale Terminals
The ST25R3920B provides the RF front-end for contactless payment terminals, supporting EMVCo and NFC Forum compliance. Its high transmitter power (1.4W) ensures reliable communication with payment cards and mobile wallets, while the -70 dBm receiver sensitivity enables reading low-signal cards. The automatic antenna tuning simplifies design across different terminal form factors, and the SPI interface allows fast data transfer to the host processor. In a typical POS terminal, the ST25R3920B is placed near the payment antenna, with the host MCU handling transaction processing. The device's low-power field detection enables battery-efficient operation in portable terminals, and its wide supply voltage range (2.4V to 5.5V) accommodates various power architectures.
Recommended
Access Control Systems
The ST25R3920B is ideal for access control readers, supporting ISO 14443A/B and FeliCa protocols used in key cards and badges. Its low-power field detection mode allows battery-operated door locks to wake up only when a card is presented, extending battery life. The device's high sensitivity ensures reliable reading of cards even when the antenna is small or the card is held at an angle. In a typical access control system, the ST25R3920B is connected to a microcontroller that validates credentials and controls the door lock. The automatic antenna tuning compensates for environmental detuning, ensuring consistent performance across installations. The device's wide operating temperature range (-40C to +85C) makes it suitable for outdoor and industrial environments.
Recommended
NFC-Enabled Smart Locks
The ST25R3920B enables NFC-based smart locks, allowing users to unlock doors with their smartphones or NFC cards. Its low-power field detection is crucial for battery-powered locks, as it keeps the device in a sleep state until an NFC field is detected. The device's high transmitter power (1.4W) ensures a reliable read range even with small antennas integrated into the lock housing. The SPI interface allows seamless integration with low-power microcontrollers, and the automatic antenna tuning simplifies the design of the antenna matching network. In a typical smart lock application, the ST25R3920B is paired with a secure element for credential storage and an MCU for lock control. The device's support for multiple protocols ensures compatibility with various NFC tags and cards.
Recommended
Industrial Asset Tracking
The ST25R3920B is used in industrial asset tracking systems to read NFC tags attached to equipment, tools, and inventory. Its robust RF front-end and high receiver sensitivity (-70 dBm) ensure reliable reading in harsh industrial environments with metal interference. The device's support for ISO 15693 allows reading of long-range tags, which is beneficial for tracking assets in warehouses. The automatic antenna tuning compensates for detuning caused by nearby metal objects, maintaining consistent performance. In a typical asset tracking application, the ST25R3920B is integrated into handheld readers or fixed gateways, with the host system logging tag IDs. The device's wide operating temperature range and low power consumption make it suitable for continuous operation in industrial settings.
Recommended
Consumer Electronics
The ST25R3920B is used in consumer electronics such as smart speakers, TVs, and wearables for NFC pairing and configuration. Its compact VQFN-32 package and low power consumption make it suitable for space-constrained designs. The device's support for peer-to-peer mode enables NFC data exchange between devices, such as sharing Wi-Fi credentials or pairing Bluetooth devices. The automatic antenna tuning simplifies the integration of the NFC antenna into the product's industrial design. In a typical consumer electronics application, the ST25R3920B is connected to the main application processor via SPI, with the NFC antenna placed near the product's surface for easy access. The device's high sensitivity ensures reliable communication even with small antennas.
Recommended
Automotive NFC
The ST25R3920B is used in automotive applications such as keyless entry systems and in-car payment. Its wide operating temperature range (-40C to +85C) and high reliability make it suitable for automotive environments. The device's support for ISO 14443A/B and FeliCa enables compatibility with various car keys and payment cards. The low-power field detection allows the system to remain in a low-power state until a key fob is presented, conserving vehicle battery. In a typical automotive application, the ST25R3920B is integrated into the door handle or dashboard, with the host MCU managing authentication and access control. The device's high transmitter power ensures reliable communication with key fobs even when the antenna is embedded in the vehicle body.
Recommended
Recommended Products Summary
Engineering reference data for ST25R3920B β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ST25R3916B | ST25R3911B | PN5180 |
|---|---|---|---|---|
| Package | VQFN-32 (5x5 mm) | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | NXP Semiconductors |
| Receiver Sensitivity | -70 dBm | -65 dBm | -60 dBm | -70 dBm |
| Transmitter Output Power | 1.4 W | 1.4 W | 0.5 W | 1.4 W |
| Automatic Antenna Tuning | Yes | No | No | No |
| Supported Protocols | ISO 14443A/B, ISO 15693, FeliCa | ISO 14443A/B, ISO 15693, FeliCa | ISO 14443A/B, ISO 15693 | ISO 14443A/B, ISO 15693 |
| Supply Voltage | 2.4V to 5.5V | 2.4V to 5.5V | 2.4V to 5.5V | 2.7V to 5.5V |
| Host Interface | SPI (up to 10 MHz) | SPI (up to 10 MHz) | SPI (up to 10 MHz) | SPI (up to 10 MHz) |
Key Differentiators
- Higher receiver sensitivity (-70 dBm) compared to ST25R3916B (vs ST25R3916B)
- Automatic antenna tuning system (vs ST25R3916B)
- Higher output power (1.4W) compared to ST25R3911B (vs ST25R3911B)
Design Notes
For optimal NFC performance, place the ST25R3920B close to the antenna and keep the RF traces short and impedance-controlled. Use a ground plane beneath the IC to minimize noise, and ensure proper decoupling with a 100nF capacitor on VCC and a 10uF capacitor on VDD_RF. The antenna matching network should be placed as close to the ANT1 and ANT2 pins as possible to reduce parasitic inductance.
The ST25R3920B can dissipate significant power when transmitting at maximum output power (1.4W). The VQFN-32 package has a thermal resistance of approximately 25 C/W (theta_JA). Ensure adequate copper area on the PCB for heat dissipation, especially in high-duty-cycle applications. For continuous operation at high power, consider adding thermal vias to the ground plane.
A common mistake is neglecting the antenna tuning. Even though the ST25R3920B has automatic antenna tuning, the antenna coil must be designed within the specified inductance range (typically 0.3uH to 2uH). Also, ensure the SPI lines are not routed near the antenna to avoid interference. Use the IRQ pin to handle interrupts efficiently rather than polling, to reduce MCU load.
Compliance Information
RoHS and REACH compliant per STMicroelectronics product page. Not AEC-Q100 qualified; for automotive use, consider ST25R3920B-AQ variant if available.
