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USB host has 26MHz SPI interface

Posted: 02 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:MAX3421E? USB host? peripheral controller? SPI interface? Maxim Integrated Products?

Maxim Integrated Products introduced the MAX3421E, a USB host and peripheral controller with an SPI interface. This device implements a full-speed (12Mbps) USB host or peripheral control compliant to USB 2.0. Embedded systems with USB host capability can interface to inexpensive USB keyboards and mice, upload firmware from USB flash drives or take advantage of the capabilities of USB devices available. The MAX3421E can also operate in the USB peripheral mode and is compatible with Maxim's MAX3420E USB peripheral controller with SPI interface.

The MAX3421E integrates a 15kV ESD-protected USB transceiver, a USB serial interface engine (SIE), double-buffered endpoint memories, an SPI slave interface, and software-controlled USB pull-up and pull-down resistors. The integrated USB transceiver supports full-speed (12Mbps) and low-speed (1.5Mbps) USB in the host mode and full-speed USB as a peripheral. The SIE handles low-level USB protocol details such as automatic NAK until ready, bit stuffing, CRC generation/checking, bus retries, automatic SOF/keep-alive generation and USB hub support in the host mode.

The MAX3421E operates using a register set accessed by the SPI interface, which operates up to 26MHz. Any SPI master (microprocessor, ASIC, DSP, etc.) can add USB functionality using the interface. A programmable interrupt output can be used to reduce or eliminate microprocessor polling. Integrated logic-level translators allow the SPI interface to operate at a system voltage between 1.4V and 3.6V. Additionally, eight general-purpose I/Os allow any microprocessor that uses I/O pins to implement the SPI interface to reclaim those pins and gain additional ones. For time-critical operations such as OTG signaling, a second interrupt pin can be dedicated to the eight general-purpose inputs, each of which can cause an interrupt.

The MAX3421E operates over the extended temperature range (-40C to 85C). This device is available in 5-by-5mm, 32-pin TQFP and 5-by-5mm, 32-pin TQFN packages. Prices start at $3.47 in quantities of 1,000.

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