Microchip Technology USB2250I-NU-06

Introduction to USB2250I-NU-06 Microchip Technology USB 2.0 Flash Media Controller

The Microchip Technology USB2250I-NU-06 is an advanced integrated circuit designed for ultra-fast, multi-slot flash media reader applications. This controller is fully compliant with the USB 2.0 specification, enabling high-speed interfacing between host systems and a broad range of popular flash memory cards. Offered in a 128-pin VTQFP package, USB2250I-NU-06 is engineered for industrial reliability and performance, supporting an operating temperature range from –40°C to +85°C, making it optimal for embedded, PC, and consumer electronics environments demanding robust operation.

Main characteristics and technical details of USB2250I-NU-06

The USB2250I-NU-06 controller package measures 14x14 mm and incorporates advanced hardware and software design choices that facilitate high-throughput and reliable card reader functionality. Its highlights include:

USB 2.0 Hi-Speed interface with integrated series termination resistors and pull-ups/pull-downs

Supports simultaneous multi-card insertion, with hardware-controlled data flow

Configurable logical unit numbers (LUNs) and flexible media assignment

Pipelined access architecture for both self-mapped and non-self-mapped media types

Four independent internal card power FETs (200mA each, with fold-back short-circuit protection)

Built-in 24 MHz crystal driver and optional external clock input

8051 8-bit microprocessor with single-cycle execution at 60 MHz, 64 KB ROM, and 14 KB RAM

Internal voltage regulator for 1.8V core operation, optimized for signal integrity

RoHS-compliant package for regulatory and environmental assurance

Unique industrial variant (“i” ordering code) for –40°C to +85°C operation

Compatible media types and standard compliances for USB2250I-NU-06

Engineered for versatility, USB2250I-NU-06 can interface with over 24 types of flash memory across the following families:

CompactFlash (CF, compliance to CF 4.1: UDMA Modes 0–4, PIO Modes 0–6)

Secure Digital (SD, compliance to SD 2.0: HS-SD, HC-SD, TransFlash, reduced form factors)

MultiMediaCard (MMC, compliance to MMC 4.2: 1/4/8 bit modes; includes MMC Streaming Mode)

Memory Stick and variants (compliant with MS 1.43, PRO 1.02, Pro-HG Duo 1.01, Duo 1.10)

SmartMedia (SM, compliant to SM 1.3)

xD-Picture Card (xD, compliant to xD 1.2; not applicable to USB2251)

The controller offers flexible configuration for single or combo sockets and supports media activity LED integration. This broad format compatibility ensures that OEMs and system integrators can provide end-users with support for the most widely used storage media.

Pinout and packaging information for USB2250I-NU-06

The USB2250I-NU-06 is delivered in a 128-pin VTQFP package (14x14x1.0 mm body, 2.0 mm pitch), optimized for signal routing and board-level integration. Its pinout supports non-multiplexed connections, enabling direct interface to independent card sockets and facilitating robust electrical isolation. The pin descriptions are organized into functional groups for each supported media type and USB interface, with defaults appropriate for most applications. Notably, the IC includes features to support hot-insertion of memory cards and the detection of MMC card write-protect status via dedicated pins.

Design structure and hardware features of USB2250I-NU-06

At the heart of the USB2250I-NU-06 is a high-performance 8051 microprocessor core, supporting single-cycle execution at up to 60 MHz. The controller includes:

Integrated regulator for stable 1.8 V operation, critical for signal integrity and low-power systems

Four independent card power FETs, each supporting a maximum of 200 mA, with short-circuit fold-back protection to ensure reliability

On-board oscillator circuit supporting fundamental mode, parallel resonant 24 MHz crystals or optional external clock (24/48 MHz)

Hardware-managed data flow for self-mapped media and pipelined architectures for non-self-mapped types, ensuring minimal latency and maximum throughput (sustained transfer rates up to 35 MB/s dependent on host/media capabilities)

Optional busor self-powered operation, with VBUS detection and power control for compliance and safety

Built-in media activity LED driver circuitry for user feedback

Software capabilities and customization options for USB2250I-NU-06

USB2250I-NU-06 offers extensive firmware customization options via an optional external EEPROM. OEMs can define unique vendor/product/language IDs, custom serial numbers, and device descriptor strings (28-character manufacturer/product, 12-digit serial). Firmware Upgrades (DFU) are supported for line or field updates. Low-latency interrupt handling and minimal memory footprint ensure responsive user experiences and optimized resource usage. Custom firmware with up to 128 KB external ROM allows for extended or proprietary features as required by advanced applications.

Setup choices and system integration guidance for USB2250I-NU-06

System integrators can configure USB2250I-NU-06 either via external 2-wire I²C EEPROM or internal defaults, supporting rapid prototyping and flexible production deployment. The device supports dynamic mapping of cards to logical units (LUNs), customized power settings for each card type (internal versus external card power FETs, with selectable limits), and media activity LED timing. Critical registers governing USB identifiers, manufacturer and product strings, language settings, power configurations, and device mapping are all accessible—either at manufacture, in-system via USB, or via EEPROM.

Key engineering considerations for integration include:

Ensuring supply ramp times less than 400 μs for reliable reset behavior

Observing maximum ratings to avoid permanent damage during power cycles and transients

Accounting for PCB parasitic capacitance in crystal circuit design for stable oscillation

Utilizing compatible hot-insertion card connectors, especially for SD card write-protect detection

Electrical parameters and environmental requirements for USB2250I-NU-06

The device operates from industrial-grade supply voltages and supports extended temperature ranges (commercial: 0°C–70°C, industrial: –40°C–85°C). Maximum ratings must not be exceeded to prevent damage—power supply design must accommodate fast ramp rates and transients. The internal regulator is used for 1.8 V core logic, while card power outputs can be configured for 100 mA or 200 mA per FET. Capacitive parameters and thermals should be managed in accordance with JESD51 recommendations, specifically soldering the exposed pad to thermal vias for optimal heat dissipation.

Possible alternative or substitute devices for USB2250I-NU-06

Within Microchip’s product family, the USB2250/50i/51/51i series encompasses related devices:

USB2250 and USB2251: Commercial variants supporting 0°C–70°C temperature.

USB2250i and USB2251i: Industrial temperature variants (–40°C to +85°C) comparable to USB2250I-NU-06.

USB2251/51i: Similar architecture, but note that xD-Picture Card support is not available on USB2251 series.

For engineering teams considering alternatives, selection of an appropriate equivalent should be based on required operating temperature range, supported media formats (especially xD), and package type. Review datasheet pinouts and peripheral compatibility to ensure drop-in replacement potential in legacy or future designs.

Conclusion

: Selecting USB2250I-NU-06 for next-generation USB flash media readers

The Microchip Technology USB2250I-NU-06 controller is a comprehensive and highly flexible solution for multi-slot USB 2.0 flash media readers, offering best-in-class support for the most popular memory card formats, robust operating temperature range, and sophisticated configuration and integration tools tailored to OEM and system integrators. With its advanced power, signal routing, and firmware customization capabilities, USB2250I-NU-06 stands out as an optimal choice for embedded designers and procurement teams aiming to deliver reliable, high-speed, and user-friendly media reader products for commercial, industrial, and consumer applications.