Microchip Technology USB2642/ML

Overview

USB2642 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, includes I²C-over-USB bridge for 50 kHz slave control, and operates across commercial (0°C to +70°C) and industrial (−40°C to +85°C) temperature ranges - deployed in desktop docking stations and multi-format media readers.

For engineers reviewing the USB2642 datasheet, USB2642 pinout, USB2642 application, or USB2642 equivalent, key selection considerations include its dual-role architecture (hub + embedded card reader), programmable PortSwap/PHYBoost features for PCB signal integrity, 48-pin QFN package with integrated VBUS detection and CRD_PWR (200 mA SD slot driver), and SPI-configurable firmware with vendor ID customization.

Technical Context

The USB2642 implements a shared Transaction Translator (TT) supporting simultaneous full-speed and low-speed peripherals across both downstream ports. Its internal 8051-based processor executes firmware from internal ROM or external SPI Flash (up to 60 MHz, dual-bit mode supported), enabling runtime configuration of vendor/product IDs, serial strings, and power management policies.

Flash media interface complies with SD 2.0 (SDSC/SDHC/SDXC), MMC 4.2 (1/4/8-bit, eMMC), and supports up to 2 TB addressable storage. The I²C-over-USB bridge uses SCSI pass-through commands via Mass Storage Class driver to perform Write_I2C_Stream and WriteRead_I2C_Stream operations with clock-stretching detection.

Key Specifications

Pinout & Package

USB2642 is housed in a RoHS-compliant 48-pin QFN package (7 mm × 7 mm, 0.5 mm pitch) with exposed thermal pad requiring multiple vias to ground. Pin functions are grouped into USB interface (10 pins), 2-port USB data (7 pins), SD/MMC interface (12 pins), SPI (4 pins), I²C (2 pins), power (6 pins), and misc./test (7 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, USB2514B offers lower unit cost but requires external components to match SD/eMMC/I²C capabilities, while GL852G supports only SDHC and lacks programmable signal integrity features - making USB2642 the sole option for compact, high-capacity, and field-configurable multi-format reader designs.

Availability

USB2642 is available at Aetrix Electronics and suitable for desktop docking stations, industrial HMI systems, and multi-format media readers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for USB2642 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 microcontroller, analog, FPGA, and connectivity solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The USB2642 belongs to Microchip's USB hub and interface controller product line, designed specifically to reduce system complexity in consumer, industrial, and computing peripherals by integrating hub, flash media, and I²C bridging functions into a single chip.

FAQ

What is the maximum SD card capacity supported by the USB2642?

The USB2642 supports storage addressability of up to 2 TB, fully compliant with SDXC specification. This enables use with modern high-capacity SDXC cards formatted with exFAT or FAT32, and is validated for sustained transfer rates exceeding 35 MB/s when paired with host and media that support those speeds. USB2642 firmware handles SDXC addressing transparently without host-side driver changes.

Does the USB2642 require an external crystal, or can it use an oscillator?

The USB2642 supports either a 24 MHz crystal (connected between XTAL1 and XTAL2) or an external 24 MHz clock source applied to XTAL1, with XTAL2 left unconnected. The internal PLL locks to this reference to generate all required clocks. No external oscillator is required beyond the 24 MHz source, and the RBIAS pin must be tied to ground with a 12.0 kΩ ±1.0% resistor to set transceiver bias currents for reliable USB signaling.

How does the USB2642 handle over-current protection on downstream ports?

The USB2642 provides per-port over-current sensing via PRTCTL2 and PRTCTL3 pins, configured as open-drain outputs with internal pull-ups. When over-current is detected, the pin is driven low, triggering automatic port power disable. Filter delay and power-on ramp timing are configurable via internal registers. USB2642 supports both discrete USB power switches and poly-fuse implementations - with diode isolation required for the latter per Figure 5-2 in DS00001578F.

Can the USB2642's SD/MMC interface support eMMC devices?

Yes, the USB2642 explicitly supports Embedded MultiMediaCard (eMMC) devices per MMC 4.2 specification, including 1-bit, 4-bit, and 8-bit bus modes. It handles eMMC boot partitions, enhanced strobe mode, and partition switching via standard SD/MMC command sets. The CRD_PWR pin delivers 3.3 V at up to 200 mA to power eMMC ICs, and firmware automatically negotiates bus width and timing based on device response during initialization.

Is external firmware required to use the USB2642, or does it operate with internal defaults?

The USB2642 operates fully with internal default firmware after power-on reset - no external SPI Flash or EEPROM is required for basic hub and SD reader functionality. External firmware is optional and used only to customize vendor/product IDs, language strings, serial numbers, or enable advanced features like ganged power control or custom port mapping. Internal ROM provides complete USB 2.0 compliance, SD 2.0 support, and I²C bridge operation out-of-box.