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Microchip Technology USB2251I-NU-06
- Part No.:
- USB2251I-NU-06
- Manufacturer:
- Microchip Technology
- Category:
- Specialized
- Package:
- 128-TQFP
- Datasheet:
-
USB2251I-NU-06.pdf
- Description:
- IC INTFACE SPECIALIZED 128VTQFP
- Quantity:
- Payment:
- Shipping:
Inventory:150
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Product details
Overview
USB2251I-NU-06 from Microchip Technology is a USB 2.0 Hi-Speed mass storage peripheral controller IC designed for multi-format flash media readers. It integrates an 8051 core (60 MHz, 64 KB ROM/14 KB RAM), supports CompactFlash 4.1, SD 2.0 (HS/HC), MMC 4.2, Memory Stick 1.43/Pro/Pro-HG Duo, SmartMedia 1.3, and features four independent 3.3 V/200 mA card power FETs. It targets commercial temperature range (0°C to +70°C) and delivers sustained transfer rates >35 MB/s with compatible media and host.
For engineers reviewing the USB2251I-NU-06 datasheet, USB2251I-NU-06 pinout, USB2251I-NU-06 application, or USB2251I-NU-06 equivalent, this page provides verified technical context, validated pin functions, confirmed flash media protocol compliance, real-world timing roles in card reader systems, and OEM-configurable firmware options including DFU support and customizable vendor/product IDs.
Technical Context
The USB2251I-NU-06 implements a hardware-controlled data flow architecture for self-mapped media (CF, SM, MS) and pipelined hardware acceleration for non-self-mapped media (SD/MMC). Its integrated 8051 processor executes firmware at single-cycle speed, managing concurrent LUN assignment across up to four physical card slots via dedicated interface buses.
It embeds a 1.8 V internal regulator, on-chip 24 MHz crystal driver, optional external 24/48 MHz clock input, and four independently controllable card power FETs with fold-back short-circuit protection - enabling robust hot-insertion support across all supported media families without external power management ICs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| USB Interface | USB 2.0 Hi-Speed (480 Mbps); integrated D+/D− termination and pull-up/down resistors |
| Processor Core | 8051-based MCU running at 60 MHz single-cycle execution; 64 KB ROM + 14 KB RAM |
| Flash Media Support | CompactFlash 4.1 (UDMA 0–4), SD 2.0 (HS-SD/HC-SD), MMC 4.2 (1/4/8-bit), Memory Stick 1.43/Pro/Pro-HG Duo, SmartMedia 1.3 |
| Card Power Outputs | 4× independent 3.3 V FETs, each rated 200 mA with fold-back short-circuit protection |
| Operating Temperature | 0°C to +70°C (commercial grade; "I" suffix denotes industrial variant - not applicable to USB2251I-NU-06) |
| Package | 128-pin VTQFP (14 × 14 mm, 0.4 mm pitch), RoHS compliant |
| Firmware Upgrade | Device Firmware Upgrade (DFU) support for external EEPROM or Flash; includes driver, sample app, and source code |
Pinout & Package
USB2251I-NU-06 is housed in a 128-pin Very Thin Quad Flat Package (VTQFP), 14 mm × 14 mm, 0.4 mm pitch, RoHS compliant. The package supports high-density PCB routing with optimized signal integrity for simultaneous multi-interface operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CF_D[15:0] | CompactFlash bidirectional data bus | True IDE mode data transfer path; weak internal pull-downs ensure stable idle state |
| SM_D[7:0] | SmartMedia bidirectional data bus | Direct NAND interface with active-low strobes (nRE/nWE); requires CRD_PWR2 for SM power |
| MS_D[7:0], MS_SCLK, MS_BS | Memory Stick serial/parallel interface | Configurable clock/data bus supporting MS Pro-HG Duo; BS pin controls bus state transitions |
| SD_D[7:0], SD_CMD, SD_CLK | Secure Digital / MMC interface | Bi-directional SD/MMC bus with weak pull-ups; supports HS-SD, HC-SD, and TransFlash |
| CRD_PWR0–CRD_PWR3 | Independent card power FET outputs | Each drives 3.3 V @ 200 mA; CRD_PWR2/CRD_PWR3 reserved exclusively for SmartMedia |
| USB+, USB−, RBIAS | USB 2.0 differential transceiver | Integrated termination; RBIAS connects to VSS via 12.0 kΩ ±1% resistor for bias current setting |
| XTAL1 (CLKIN), XTAL2 | 24 MHz clock source interface | Supports crystal or external 24/48 MHz clock; MA[1:0] sampled at reset to select source |
| nRESET | Active-low global reset input | Minimum 1 µs pulse width; initializes all interfaces and internal state machines |
Key Features
| Feature | Design Value |
|---|---|
| Multi-slot media arbitration | Hardware-managed concurrent access to CF, SD, MS, and SM sockets with flexible LUN mapping |
| On-chip power regulation | Integrated 1.8 V core regulator (VDD18/VDD18PLL); eliminates need for external DC/DC converter |
| OEM firmware customization | Vendor/product ID, serial number (12-hex max), language strings, and custom EEPROM-based data supported |
| Hot-insertion readiness | All card interfaces include detection pins (CF_nCD, SM_nCD, MS_INS, SD_nCD) and FET-controlled power sequencing |
| Low-latency interrupt handling | Optimized firmware ISR design reduces host polling overhead and improves read/write response time |
Applications
| Flash Media Card Reader | USB Printers with SD Slot |
|---|---|
Use Scenario: Desktop or portable multi-card reader supporting CF, SD, MS, and SM in a single enclosure. IC Role / Device Role / Timing Role: Central USB-to-flash bridge; manages protocol translation, DMA coordination, and per-slot power control. Use Value: Enables >35 MB/s sustained throughput across media types using single-chip integration - no external microcontroller or power ICs required. |
Use Scenario: Mid-range office printer with integrated SD card slot for direct photo printing. IC Role / Device Role / Timing Role: SD host controller interfacing between printer SoC and removable media; handles SD initialization, command/response timing, and block transfers. Use Value: Offloads SD protocol stack from main printer CPU; supports SD 2.0 HC/HS modes for fast image loading without firmware bloat. |
| Mobile PC Media Dock | Vista ReadyBoost™ Adapter |
Use Scenario: Ultrabook docking station with dual SD/CF slots for field data acquisition. IC Role / Device Role / Timing Role: High-bandwidth USB peripheral controller; synchronizes CF UDMA Mode 4 and SD HS timing under host OS driver control. Use Value: Delivers deterministic latency and error recovery for time-sensitive imaging workflows - validated for Windows/Linux UAS and BOT drivers. |
Use Scenario: External ReadyBoost-compatible cache device using SD or CF as system acceleration storage. IC Role / Device Role / Timing Role: Mass storage class endpoint with optimized write coalescing and wear-leveling-aware firmware layer. Use Value: Meets Microsoft ReadyBoost™ latency and IOPS requirements via hardware-accelerated command queuing and internal buffer management. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar USB flash media controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| USB2244-BZK | Single-slot SD/MMC-only controller; no CF/MS/SM support; 64-pin QFN; lower BOM cost | Limited to SD/TransFlash use cases; lacks multi-format flexibility and LUN configurability | Select when only SD/SDHC support is needed and space/cost constraints preclude 128-pin VTQFP |
| GL827L-QLF | USB 2.0 multi-format controller with CF/SD/MS/SM support; different pinout; requires external 1.8 V regulator | Similar feature set but distinct register map and firmware API; no integrated 1.8 V core regulator | Choose if existing layout accommodates GL827L's 128-pin LQFP and external regulator is already present |
Compared with USB2251I-NU-06, USB2244-BZK sacrifices format breadth for compactness and cost, while GL827L-QLF matches multi-slot capability but shifts power design responsibility to the board - making USB2251I-NU-06 optimal for new designs prioritizing integration, thermal efficiency, and firmware portability.
Availability
USB2251I-NU-06 is available at Aetrix Electronics and suitable for flash media card readers, USB printers with SD slots, and mobile PC media docks requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for USB2251I-NU-06 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
Microchip Technology Inc. is a leading provider of microcontrollers, analog components, and connectivity solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.
The USB2250/51 family was engineered specifically for USB-connected flash media readers - integrating protocol engines, power FETs, and firmware infrastructure to eliminate discrete logic and reduce time-to-market for multi-format card reader designs.
FAQ
What is the operating temperature range for USB2251I-NU-06?
The USB2251I-NU-06 is rated for commercial temperature operation from 0°C to +70°C. Note that the "I" in the part number refers to the industrial-grade USB2251i variant (-40°C to +85°C); USB2251I-NU-06 itself is the commercial version. This distinction is explicitly stated in Microchip's DS00002005A datasheet Section 1.0 and Table 4-1.
Does USB2251I-NU-06 support xD-Picture Card?
No, USB2251I-NU-06 does not support xD-Picture Card. The datasheet footnote on page 1 states: "xD-Picture Card not applicable to USB2251." While the USB2250/50i variants include xD support via the SCL/xD_ID pin, USB2251/51i omit this functionality - confirmed in Pin Descriptions (Table 5-1) where xD_ID is marked as "only applicable to USB2250/USB2250i."
What clock sources does USB2251I-NU-06 accept?
USB2251I-NU-06 accepts either a 24 MHz crystal (connected across XTAL1 and XTAL2) or an external 24 MHz or 48 MHz clock applied to XTAL1 (CLKIN), with XTAL2 left open. The clock source is selected by sampling MA[1:0] during nRESET assertion - '00' selects 24 MHz, '11' selects 48 MHz. This configuration is documented in Section 5.1 and Figure 6-1 of DS00002005A.
How many logical units (LUNs) can USB2251I-NU-06 manage simultaneously?
USB2251I-NU-06 supports flexible LUN assignment across its four physical card slots (CF, SD/MMC, MS, SM), with firmware-configurable mapping - enabling up to four independent LUNs. The datasheet highlights "flexible assignment of number of LUNs and how card types are associated with the LUNs" in Highlights (page 1) and confirms hardware support for multiple simultaneous card insertions in Section 1.0.
Is USB2251I-NU-06 pin-compatible with USB2250 or USB2251 variants?
Yes, USB2251I-NU-06 shares the identical 128-pin VTQFP footprint and pinout with USB2250, USB2250i, and USB2251 - confirmed by the unified "USB2250/50i/51/51i" designation throughout DS00002005A, including Pin Configuration (Figure 2-1), Pin Table (Table 4-1), and Pin Descriptions (Table 5-1). Functional differences (e.g., xD support, temp grade) do not affect mechanical or electrical pin compatibility.
USB2251I-NU-06 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 128-TQFP
- Packaging:
- Tray
- Product Status:
- Active
- Applications:
- Controller
- Interface:
- -
- Voltage - Supply:
- 3.3V
- Supplier Device Package:
- 128-VTQFP (14x14)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
USB2251I-NU-06 FAQ
1.How can I place an order for USB2251I-NU-06 through Aetrix?
Please submit a Request for Quotation (RFQ) for USB2251I-NU-06 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 USB2251I-NU-06 reliable?
The price and inventory of USB2251I-NU-06 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for USB2251I-NU-06 is usually 5 days.
3.What payment methods are accepted for USB2251I-NU-06?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for USB2251I-NU-06 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for USB2251I-NU-06?
USB2251I-NU-06 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your USB2251I-NU-06 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 USB2251I-NU-06?
For technical support, including USB2251I-NU-06 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your USB2251I-NU-06 requirements.
6.How does Aetrix verify that USB2251I-NU-06 is sourced from the original manufacturer or authorized distributors?
All USB2251I-NU-06 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 USB2251I-NU-06 meets industry standards.
7.What is the process for return or replacement of USB2251I-NU-06?
All USB2251I-NU-06 units undergo pre-shipment inspection (PSI). If there is an issue with USB2251I-NU-06, 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 USB2251I-NU-06 part is unused and in its original packaging.
Return procedure for USB2251I-NU-06:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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