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STMicroelectronics ST25RU3991-BQFM
- Part No.:
- ST25RU3991-BQFM
- Manufacturer:
- STMicroelectronics
- Category:
- RFID, RF Access, Monitoring ICs
- Package:
- 64-VFQFN Exposed Pad
- Datasheet:
-
ST25RU3991-BQFM.pdf
- Description:
- IC RFID READER 860-960MHZ 64QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,449
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Product details
Overview
ST25RU3991-BQFM from STMicroelectronics is a UHF RFID reader IC compliant with ISO/IEC 18000-6C (EPC Gen2) and supporting ISO 18000-6A/B in direct mode. It integrates analog front-end, protocol engine, 20 dBm internal PA, ASK/PR-ASK modulation, AM/PM demodulation, and 24-byte FIFO. Designed for handheld and embedded UHF RFID readers requiring compact footprint and low-power operation.
For engineers reviewing the ST25RU3991-BQFM datasheet, ST25RU3991-BQFM pinout, ST25RU3991-BQFM application, or ST25RU3991-BQFM equivalent, key selection considerations include EPC Gen2 protocol stack integration, dual-mode (normal/direct) host interface flexibility, on-chip VCO/PLL covering 840–960 MHz, integrated RSSI measurement, and configurable RX gain/bandwidth for varying tag link budgets.
Technical Context
The ST25RU3991-BQFM implements a full ISO18000-6C protocol stack with hardware-accelerated framing, CRC generation/checking, and command execution (e.g., Query, ACK, ReqRN). Its analog front-end includes differential mixer inputs (MIX_INP/MIX_INN), programmable RX filters, AGC (patent pending), and selectable sub-carrier decoders delivering bit stream + clock outputs.
Transmitter operation supports ASK or PR-ASK modulation with adjustable index and built-in FrameSync/Preamble/CRC insertion. The device operates in three power modes (active, standby, power-down), accepts 1.8–5.5 V I/O voltage, and provides regulated 3.3 V/20 mA supply (VDD_IO) and dedicated RF path regulators (VDD_RFP, VDD_RF, VDD_A).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Protocol Support | Fully compliant with ISO/IEC 18000-6C (EPC Gen2); backward compatible with ISO 18000-6A/B in direct mode. |
| RF Frequency Range | 840–960 MHz via integrated VCO and PLL; no external synthesizer required. |
| Output Power | 20 dBm into 50 Ω load using internal PA - sufficient for short-to-medium range handheld reader applications. |
| Modulation Schemes | ASK and PR-ASK with adjustable modulation index - enables optimization for tag sensitivity and read reliability. |
| RX Demodulation | Simultaneous AM and PM demodulation with automatic I/Q selection - eliminates communication holes across diverse tag types. |
| Host Interface | Configurable 8-bit parallel or 4-pin SPI; 24-byte FIFO buffers protocol data to reduce MCU overhead. |
| RSSI Measurement | Digitized AM/PM signal strength accessible via dedicated register - enables real-time link quality monitoring and adaptive power control. |
Pinout & Package
ST25RU3991-BQFM is housed in a 64-pin QFN package (9 mm × 9 mm, 0.5 mm pitch) with exposed thermal pad (EXP_PAD) requiring connection to GND for thermal and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IO0–IO7 | Parallel I/O or SPI signals | Configurable as 8-bit data bus (parallel) or MOSI/MISO/SS/SCK (SPI); support direct mode control and sub-carrier output. |
| CLK / CLSYS | Timing interface | CLK accepts external clock (up to 20 MHz); CLSYS delivers programmable clock output (1–20 MHz) for MCU synchronization. |
| IRQ | Interrupt signaling | Active-low interrupt indicates FIFO status, command completion, or error condition - enables event-driven host firmware. |
| RFOUTP_1 / RFOUTN_1 | Differential RF output | PA output pair; must be tied together with RFOUTP_2/RFOUTN_2 for single-ended operation or used differentially for improved noise immunity. |
| ADC / DAC | Analog calibration interface | ADC monitors external RF power detector; DAC controls bias of external PA - enables closed-loop TX power management. |
| VDD_IO / VDD_A / VDD_RFP | Supply domains | Separate regulated supplies (3.4 V) for I/O, analog, and RF path - minimize cross-domain noise coupling and ensure signal integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated protocol engine | Hardware-executed EPC Gen2 commands (Query, ACK, ReqRN) offload MCU and guarantee deterministic timing compliance. |
| Dual-mode host interface | Switch between FIFO-based buffered mode (for protocol handling) and real-time direct mode (for custom waveform generation or legacy tag support). |
| Programmable RX chain | Selectable corner frequencies for LPF/HPF, discrete gain steps, and AGC enable adaptation to varying tag modulation depth and distance. |
| On-chip supply regulation | Dedicated LDOs for digital (VDD_D), analog (VDD_A), RF path (VDD_RFP), and PA (VDD_RF) suppress supply noise and simplify board-level power design. |
| Crystal oscillator support | 20 MHz crystal input (OSCI/OSCO) with internal buffer - eliminates need for external clock generator and reduces BOM count. |
Applications
| Handheld RFID Reader | Fixed-Position Asset Tracker |
|---|---|
|
Use Scenario: Battery-powered portable device scanning pallets, tools, or library books in warehouse or field environments. IC Role / Device Role / Timing Role: Primary UHF reader SoC managing RF transmission, tag response decoding, and protocol state machine execution. Use Value: Integrated 20 dBm PA and low-power modes extend battery life; compact QFN package enables slim industrial enclosure design. |
Use Scenario: Wall-mounted or pole-mounted reader monitoring equipment movement in hospitals or manufacturing floors. IC Role / Device Role / Timing Role: Core transceiver controlling antenna switching, frequency hopping, and multi-tag inventory cycles. Use Value: Programmable RX bandwidth and AGC maintain reliable reads despite metal interference or variable tag orientation. |
| Smart Shelf Inventory System | Logistics Gate Reader |
|
Use Scenario: Embedded reader behind retail shelf edges detecting item presence, count, and reordering triggers. IC Role / Device Role / Timing Role: Low-voltage (1.8 V I/O) interface to microcontroller; handles dense tag populations with anti-collision logic. Use Value: Parallel/SPI flexibility allows integration with cost-optimized MCUs; RSSI register enables proximity-based shelf occupancy inference. |
Use Scenario: High-throughput portal reader at shipping dock verifying container contents during loading/unloading. IC Role / Device Role / Timing Role: High-duty-cycle transmitter coordinating multiple antennas and executing rapid tag interrogation bursts. Use Value: Direct mode bypasses protocol engine for custom timing sequences; DAC/ADC support enables precise TX power calibration across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar UHF RFID reader applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Impinj Speedway R2000 | Discrete RF front-end + FPGA-based protocol processor; requires external PA, ADC, and clock synthesis. | Targeted at high-performance fixed readers with multi-antenna support and Ethernet connectivity. | Choose when system-level flexibility, field-upgradable firmware, and >30 dBm output are required - not a drop-in replacement. |
| NXP MRU100 | Single-chip solution with 18 dBm PA, supports only EPC Gen2; lacks direct mode, DAC/ADC, and programmable RX filters. | Suitable for cost-sensitive, low-complexity readers where tag compatibility breadth is secondary. | Choose for simplified design and lower BOM cost if advanced features like AGC tuning or external PA control are unnecessary. |
Compared with Impinj R2000 and NXP MRU100, ST25RU3991-BQFM uniquely balances integration (on-chip PA, regulators, protocol engine) with configurability (direct mode, RX filter/gain control, DAC/ADC), making it optimal for mid-tier handheld and embedded readers needing both performance and design efficiency.
Availability
ST25RU3991-BQFM is available at Aetrix Electronics and suitable for handheld RFID readers, fixed-position asset trackers, smart shelf systems, and logistics gate readers requiring stable component supply and long-term manufacturability.
Supply support for ST25RU3991-BQFM includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in microcontrollers, power management, sensors, and analog/mixed-signal ICs for industrial, automotive, and consumer markets.
The ST25RU series targets UHF RFID infrastructure, emphasizing single-chip integration, low-power operation, and EPC Gen2 compliance for compact, cost-effective reader designs - bridging performance and ease of implementation.
FAQ
What is the maximum output power and how is it achieved?
The ST25RU3991-BQFM delivers up to 20 dBm into a 50 Ω load using its integrated power amplifier. This output level is achieved without external matching components when driving a 50 Ω antenna port, and is verified under typical operating conditions (VDD_RF = 3.0 V, TA = 25°C). Output power remains stable across temperature due to internal regulation and bias control.
Does the IC support external VCO or crystal oscillator only?
The ST25RU3991-BQFM uses an internal VCO and PLL locked to a 20 MHz crystal oscillator (connected to OSCI/OSCO pins). An external RF source can be injected via EXT_IN only in configurations where the internal VCO is disabled - this mode is intended for specialized test or hybrid architectures, not standard operation.
How does the direct mode differ from normal mode in host communication?
In normal mode, the IC handles full EPC Gen2 protocol framing, CRC, and command execution autonomously using the 24-byte FIFO. In direct mode, coders/decoders are bypassed: the host MCU directly controls baseband waveforms and processes raw sub-carrier signals - enabling proprietary protocols or legacy tag support beyond Gen2.
Can the ST25RU3991-BQFM operate from a USB 5 V supply?
Yes - the VEXT pin accepts 5.0–5.5 V input, and internal regulators generate all required supply rails (VDD_RF, VDD_A, VDD_D, VDD_IO). No external DC-DC conversion is needed, simplifying power design for USB-powered handheld readers and evaluation platforms.
ST25RU3991-BQFM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- ST25R
- Package/Case:
- 64-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- RFID Reader
- Frequency:
- 860MHz ~ 960MHz
- Standards:
- EPC, ISO 18000-6
- Interface:
- SPI
- Voltage - Supply:
- 5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-QFN (9x9)
ST25RU3991-BQFM FAQ
1.How can I place an order for ST25RU3991-BQFM through Aetrix?
Please submit a Request for Quotation (RFQ) for ST25RU3991-BQFM on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ST25RU3991-BQFM reliable?
The price and inventory of ST25RU3991-BQFM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST25RU3991-BQFM is usually 5 days.
3.What payment methods are accepted for ST25RU3991-BQFM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST25RU3991-BQFM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ST25RU3991-BQFM?
ST25RU3991-BQFM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ST25RU3991-BQFM order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ST25RU3991-BQFM?
For technical support, including ST25RU3991-BQFM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST25RU3991-BQFM requirements.
6.How does Aetrix verify that ST25RU3991-BQFM is sourced from the original manufacturer or authorized distributors?
All ST25RU3991-BQFM products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ST25RU3991-BQFM meets industry standards.
7.What is the process for return or replacement of ST25RU3991-BQFM?
All ST25RU3991-BQFM units undergo pre-shipment inspection (PSI). If there is an issue with ST25RU3991-BQFM, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ST25RU3991-BQFM part is unused and in its original packaging.
Return procedure for ST25RU3991-BQFM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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