Microchip Technology USB2642-I/ML

Overview

USB2642-I/ML from Microchip Technology is a USB 2.0-compliant, single-chip hi-speed hub and flash media controller combo IC. It integrates a 2-port downstream USB 2.0 hub with an SD/MMC/eMMC card reader (exposed as a compound device on port #3), supports sustained flash transfer rates >35 MB/s, features I²C-over-USB bridge capability at 50 kHz, and operates across industrial temperature range (–40 °C to +85 °C). It serves in embedded USB expansion and multi-format card reader applications.

For engineers reviewing the USB2642-I/ML datasheet, USB2642-I/ML pinout, USB2642-I/ML application, or USB2642-I/ML equivalent, key selection criteria include its dual-role architecture (hub + flash controller), 48-pin QFN package with integrated PHYBoost and PortSwap, support for SDXC/eMMC up to 2 TB, and configurable power management per downstream port.

Technical Context

The USB2642-I/ML implements a shared Transaction Translator (TT) for both downstream ports, enabling concurrent full-speed and low-speed peripheral operation. Its internal 8051-based processor executes firmware from internal ROM or external SPI Flash (up to 60 MHz), supporting custom vendor/product IDs and runtime configuration via I²C EEPROM.

It embeds three functional domains: a USB 2.0 upstream/downstream transceiver with programmable drive strength (PHYBoost), a dedicated SD/MMC interface with 8-bit data bus and command/control signals, and an I²C-over-USB bridge that maps SCSI pass-through commands to I²C master transactions - all synchronized to a single 24 MHz crystal.

Key Specifications

Pinout & Package

USB2642-I/ML uses a 48-pin QFN (7 × 7 mm²) package with exposed thermal pad (VSS connection required via multiple vias). Pin functions are grouped by interface: Secure Digital (12 pins), USB 2.0 (10 pins), 2-port USB interface (7 pins), SPI (4 pins), I²C (2 pins), MISC (7 pins), and POWER (6 pins).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar USB hub and flash media controller applications.

Compared with USB2642-I/ML, USB2641-I/ML reduces integration by removing flash media capability, while USB5744-AEZG-TR increases port count but adds system complexity through external flash controller dependency - making USB2642-I/ML optimal for cost-sensitive, space-constrained designs requiring native SD/MMC support.

Availability

USB2642-I/ML is available at Aetrix Electronics and suitable for desktop docking, consumer A/V equipment, and industrial printers requiring stable component supply, long-term lifecycle support, and industrial-grade temperature operation.

Supply support for USB2642-I/ML 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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The USB2642-I/ML belongs to Microchip's USB Hub and Flash Controller product line, designed specifically for embedded systems requiring integrated USB expansion and multi-format flash media access in a single chip.

FAQ

What is the maximum flash storage capacity supported by the USB2642-I/ML?

The USB2642-I/ML supports storage addressability up to 2 TB, fully compliant with SDXC and eMMC specifications. This capacity is enabled through native SD 2.0 and MMC 4.2 protocol support, and requires compatible host drivers and flash media. The USB2642-I/ML itself imposes no internal file-system or logical block addressing limitation beyond those defined in the standards it implements.

Does the USB2642-I/ML require an external crystal, or can it use an oscillator?

The USB2642-I/ML accepts either a 24 MHz crystal (connected between XTAL1 and XTAL2) or a 24 MHz external clock source applied to XTAL1, with XTAL2 left unconnected. The internal PLL locks to this reference to generate all required clocks. No additional clock conditioning circuitry is needed, and the device does not support other frequencies or internal RC oscillators.

How does the I²C-over-USB bridge in the USB2642-I/ML operate?

The USB2642-I/ML implements an I²C-over-USB bridge using SCSI pass-through commands routed through its Mass Storage Class interface. Host software issues Write_I2C_Stream or WriteRead_I2C_Stream commands, which the USB2642-I/ML translates into physical I²C transactions at up to 50 kHz. Clock stretching during reads is detected and handled transparently, and the SCL/SDA pins are directly accessible on the QFN package.

Can the USB2642-I/ML be configured without external memory?

Yes - the USB2642-I/ML boots from internal ROM with default configuration, supporting basic hub and SD/MMC functionality out-of-box. External SPI Flash or I²C EEPROM is optional and used only to override defaults: custom VID/PID, strings, port mapping, power settings, or firmware updates. No external memory is required for operation, though it enables full feature customization.

What is the function of the CRD_PWR pin on the USB2642-I/ML?

The CRD_PWR pin on the USB2642-I/ML is a 200 mA, 3.3 V open-drain output that powers the SD/MMC socket. It is controlled via bits 0–3 of register A5h and supports programmable timing for power-on sequencing. Unlike PRTCTLx pins (which switch 5 V to USB peripherals), CRD_PWR delivers regulated 3.3 V directly to the flash media interface, enabling safe hot-plug detection and write-protection handling via SD_nCD and SD_WP pins.