RTL9211DS - USB 3.2 Gen2 to SD Express Bridge Controller
MPN: RTL9211DS ✓ Active| Qty | Unit Price | Extended |
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| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
RTL9211DS Overview
An SD Express bridge controller is an interface IC that translates commands and data between a host protocol and an SD Express card. In this product, the USB 3.2 Gen2 side communicates with the host, while the SD Express side handles the card interface. This hierarchy places RTL9211DS at the intersection of USB bridge controllers, storage interface controllers, and computer interface semiconductors. The reported 985 MB/s figure describes the stated SD Express port data transmission speed; it should not be interpreted as guaranteed end-to-end throughput for every enclosure, host, card, operating system, or transfer workload.
Key verified features include USB 3.2 Gen2 connectivity, SD 8.0 and SD 7.1 protocol support, a stated 10 Gbps bridge-controller class, 985 MB/s SD Express transmission speed, and support for a theoretical 128 TB SD card. The Realtek product page identifies the RTL9211DS as suitable for several market segments, including desktop, mobile, workstation, server, communications platforms, and embedded systems. The associated SD Association material lists USB-interface reader implementations using RTL9211DS for detachable devices such as docking stations, dongles, and USB card readers.
The controller is appropriate when a product needs a compact USB-to-SD Express bridge rather than an internal PCIe-based reader. A USB host can enumerate the bridge, while the bridge manages the card-side interface and data transfer. Actual performance depends on USB link negotiation, host controller behavior, SD Express card capability, thermal conditions, firmware, and the selected mechanical implementation. The verified source does not provide a detailed timing, electrical, package, or pinout table, so designers should obtain the applicable Realtek technical documentation before final schematic capture or PCB release.
Typical applications include USB card readers, docking stations, portable storage accessories, workstation peripherals, and embedded systems that need removable SD Express storage over USB. For consumer products, the controller is relevant where SD Express is needed for higher transfer rates than legacy SD card interfaces. For embedded and industrial systems, it can support removable storage or controlled update media, subject to the mechanical and environmental requirements of the final product.
The main design consideration is validation: confirm the exact RTL9211DS package, exposed pins, power rails, reference circuitry, firmware requirements, and host compatibility using Realtek documentation. USB routing requires controlled impedance and careful connector, power, and return-path layout. Storage designs should also verify card insertion, removal, power-state transitions, thermal behavior, and enclosure grounding before production.
Drop-in alternatives for RTL9211DS — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with RTL9211DS (same form factor and footprint) — differing in Product Type, Target Applications.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
RTL9220DP
✅ Drop-In✓ In Stock
Contact for price
View Datasheet →RTS5264
✅ Drop-In📋 Reference alternative (not in catalog)
RTS5261
✅ Drop-In📋 Reference alternative (not in catalog)
RTL9211DS Specifications
| Product Type | USB 3.2 Gen2 to SD Express bridge controller |
| Host Interface | USB 3.2 Gen2 |
| Host Interface Data Rate | 10 Gbps |
| SD Express Port Speed | 985 MB/s |
| Supported SD Protocol | SD 8.0 and SD 7.1 |
| Maximum Theoretical SD Card Capacity | 128 TB |
| Target Applications | Desktop, mobile, workstation, server, communications platform, and embedded |
| Typical Device Form | Docking station, dongle, and USB card reader |
| Interface Category | Bridge controller |
| Storage Interface | SD Express |
| Manufacturer | Realtek |
RTL9211DS standard Pin Configuration Guide
Pin configuration for RTL9211DS (standard package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for RTL9211DS.
Refer to the datasheet for full pin configuration.
Typical Applications
RTL9211DS is suitable for 6 applications: USB SD Express Card Reader, Docking Station Storage Module, Portable USB Storage Dongle, Workstation External Storage, Mobile Device Storage Accessory, Embedded Removable Storage.
USB SD Express Card Reader
The RTL9211DS fits a USB card reader because it bridges USB 3.2 Gen2 to SD Express storage, with Realtek reporting up to 985 MB/s on the SD Express port. The controller can sit between a USB-C or USB-A reader implementation and an SD Express card, reducing the need for a custom host-side storage interface. The design should preserve controlled USB impedance, provide stable power for the bridge and card, and validate card insertion and removal behavior. The stated 10 Gbps USB class and 985 MB/s SD Express figure describe link capabilities, while real user throughput will depend on the host, card, firmware, and workload.
Recommended
Docking Station Storage Module
RTL9211DS is applicable to a docking station that exposes removable SD Express storage over USB. The verified SD Association material specifically identifies RTL9211DS with USB reader implementations including docking stations. In this arrangement, the dock can provide a user-accessible SD Express slot without requiring the host computer to expose a native SD Express or PCIe card interface. Designers should account for USB connector orientation, cable loss, power-enable sequencing, card detection, mechanical retention, and enclosure grounding. The controller’s reported 985 MB/s SD Express speed is useful for product positioning, but sustained transfer rate must be measured in the completed dock.
Recommended
Portable USB Storage Dongle
The RTL9211DS can support a compact USB storage dongle that accepts SD Express media and presents it as a removable USB peripheral. Its USB 3.2 Gen2 interface is suitable for a modern host, while the SD Express side targets high-speed card access. A dongle implementation should minimize cable and connector loss, maintain USB signal integrity, and provide clean power for both the controller and the card. The verified Realtek data also identifies mobile and embedded applications, making the device class relevant to portable storage accessories. Before release, validate thermal rise, insertion cycles, unplug behavior, and compatibility across host operating systems.
Recommended
Workstation External Storage
RTL9211DS is suitable for an external workstation storage accessory when the workstation relies on USB rather than an internal card slot. The controller provides a bridge from USB 3.2 Gen2 to SD Express, allowing high-capacity SD media to appear as a removable storage device. Realtek’s verified market list includes workstations and servers, while the stated theoretical capacity support reaches 128 TB. For workstation use, validate sustained throughput, thermal behavior, hot-plug behavior, filesystem support, and host compatibility. USB cable quality and the selected card can materially affect the achieved transfer rate, so the published 985 MB/s port figure should be treated as a maximum stated capability.
Recommended
Mobile Device Storage Accessory
The RTL9211DS can be used in a mobile-oriented storage accessory that adds SD Express connectivity through USB. Realtek lists mobile among the suitable application segments, and the USB bridge architecture avoids requiring a dedicated SD Express host interface in the portable product. Implementation attention should focus on USB power budget, connector robustness, card access latency, and battery impact. The controller’s stated 10 Gbps USB class is appropriate for high-speed transfer, but practical energy use depends on link state, card activity, and system firmware. Validate suspend, resume, card removal, and thermal conditions across the intended host devices before production.
Recommended
Embedded Removable Storage
RTL9211DS is relevant to an embedded system that needs removable SD Express media over a USB host interface. The controller can simplify the host-side connection when the embedded platform already supports USB but does not directly expose SD Express. The completed design must define startup behavior, card detection, filesystem ownership, read-only versus writable operation, and recovery after unexpected removal. Realtek identifies embedded applications among the supported markets, but the supplied evidence does not name a specific processor, bootloader, operating system, or driver. Those items should be verified as an integration package rather than assumed from the controller’s transfer-rate specification.
Recommended
Recommended Products Summary
Engineering reference data for RTL9211DS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | RTL9220DP | RTS5264 | RTS5261 |
|---|---|---|---|---|
| Product Category | USB 3.2 Gen2 to SD Express bridge controller | USB SD Express reader controller candidate | PCIe SD Express reader controller candidate | PCIe SD Express reader controller candidate |
| Brand | Realtek | Realtek | Realtek | Realtek |
Key Differentiators
- USB-to-SD Express bridge positioning (vs RTS5264)
- Reported SD Express transfer capability (vs RTL9220DP)
- Protocol and capacity positioning (vs RTS5261)
Design Notes
Treat the USB 3.2 Gen2 path as a controlled-impedance interface rather than a generic USB connection. Use the connector, controller, and transceiver geometry recommended by the current Realtek reference design, keep the USB differential pair continuous, and provide a continuous return path. Estimating the propagation delay or insertion loss is not possible from the supplied data, so use measured or manufacturer-provided constraints rather than guessed length limits.
Place USB and SD Express routing components close to their associated connector or controller pins, with short high-speed paths and carefully managed return-current continuity. Keep noisy switching and power-conversion nodes away from the USB differential pair. The verified sources do not provide a pinout or layout reference, so final trace width, spacing, via count, and stackup must follow the applicable Realtek design guidance.
Design the power tree for both the controller and the attached SD Express card. Estimate current draw from the actual card, USB source, controller state, and any inrush behavior, then size supply paths and decoupling using the datasheets for every component. The supplied RTL9211DS material does not specify operating voltage or current, so a numerical regulator selection or dissipation calculation would be speculative.
Do not equate the stated 985 MB/s SD Express port speed with guaranteed end-to-end transfer throughput. Validate sustained performance with the target host, USB cable, enclosure, SD Express card, filesystem, and application workload. Also test card insertion, removal, suspend, resume, short-circuit behavior, and power-cycle recovery because the verified product description does not specify these implementation details.
Compliance Information
The supplied Realtek product page and search results do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. These fields remain unknown rather than being inferred.
