Review

Quite a few devices came on the scene this year for peripheral connectivity, particularly in the USB arena. Chips that make portable products USB ready, provide charging, control, and a variety of other functions made a strong showing, as well as devices for FireWire, RS-232, and RS-485.

Enhancing mobile phones, digital cameras, PDAs, and other mobile products with USB 1.1 performance, Fairchild Semiconductor's (fairchildsemi.com). USB1T11-ABQ transceiver broke the size barrier in a MLP. The 1-mm high chip, said to be 84% smaller than comparable TSSOP or SOIC devices, interfaces 5V or 3.3V standard or programmable logic to the USB physical layer and supports both 12 and 1.5 Mb/s data rates.

The NET2272 16-bit, USB 2.0 device controller from Netchip Technology (netchip.com). introduced the company's unique Dynamic Virtual Endpoint technology, which allows the device to support the maximum number of allowable USB endpoints to be configured. Users can create up to 30 independent data channels by mapping multiple data streams over existing endpoints.

Trimming part counts, the MAX3450E, MAX3451E and MAX3452E USB transceivers from Maxim Integrated Product (maxim-ic.com) are ±15 kV protected as per the human body model, eliminating the need for external protection circuitry. The devices are compliant with USB specs revision 1.1 and 2.0 and operate at 1.5 or 12 Mb/s. They also include a low-power suspend mode and have the ability to work with ASICs operating on 1.65V.

Providing both high-speed (480 Mb/s) and full-speed (12 Mb/s) control along with bulk and interrupt transfers, the M66591GP USB 2.0 peripheral controller from Mitsubishi Electric (mitsubishielectric.com) packs a wealth of functions in an 80-pin, 10 mm x 10 mm LQFP with a 0.4 mm pitch. These include power management, a 1.8V or 3.3V power-source interface, USB transceiver, multi-function high-speed bus interface, an 8-bit DMA interface, a multiplex-selectable, 16-bit CPU bus, and a 3.5 KB FIFO.

Advanced Analogic Technologies (analogictech.com) described its AAT3125 as the market's first integrated USB power management device to conform to the USB on-the-go (OTG) specification. The device employs a charge pump topology to regulate the 5V output and to deliver an output current up to 100 mA. It also integrates all voltage monitoring to ensure OTG compatibility.

Mating a dual RISC-core architecture with a USB host stack, hub driver, plus basic USB drivers, the AT43USB370 device from Atmel (atmel.com) promises to manage USB host activities without the need for processor intervention. Its USB 2.0 host/function processor levels enough on-chip intelligence to offload USB device driver functionality from the system processor.

Texas Instruments (ti.com) introduced the first 1394b FireWire devices for home networking applications, the TSB41BA3 three-port bilingual physical layer and TSB17BA1 transceiver. The IEEE 1394b-2002-compliant TSB41BA3 operates at speeds up to 400 Mb/s and automatically detects and corrects loops, allowing the use of any cable topology. The single-port TSB17BA1 operates as a one-port, 100 Mb/s transceiver and handles 1394b connections over Category 5 cable.

Despite certain speculations and rumors of their demise, the venerable RS-232 and RS-485 interfaces were still a focus of interest in 2003. Designed to convert RS-232 ports to multi-drop networks, the MAX3322E and MAX3323E transceivers from Maxim Integrated Products feature a switchable input impedance: 5 kΩ for RS-232 and greater than 1 MΩ for multi-drop applications.

Addressing noise faults, Texas Instruments' SN65HVD2X family debuted as the industry's first extended common-mode RS-485 transceivers. Specifying a common-mode voltage range from ­20V to +25V, the devices surpass TIA/EIA-485 requirements by greater than 100%.

—Mat Dirjish

Outlook

I/O We Go
It's clear that, at some point, anything that plugs in and/or runs on batteries will interface to a host system of sorts. It's not a novel concept that common home appliances, refrigerators, microwave ovens, etc. are now viewed as potential computer peripherals. Unique interfaces, as well as a plethora of new standards for existing interfaces will emerge, making this both a challenging and rewarding environment for peripheral device makers.

USB and FireWire ports will be around for a long time, supplanting standard serial and parallel ports on the consumer end where extreme ease of use is required. There are embedded-system apps that require the reliability, stability, backward compatibility, and cost effectiveness of these older, proven interfaces. How long that will be is hard to tell, but, over all, the future looks bright for the interface-chip market.

—MD