Wave Issue 9039 X/XX/99 Article 4-01

***ASIC-to-USB Signal-Level Bridge IC Enables Mobile USB
(Arpil 1)

Micrel’s MIC2550 Universal Serial Bus (USB) Transceiver is a USB-
compliant IC that serves as a voltage translation bridge between
the signaling levels of a mobile system’s ASICs and standard USB
levels, without any additional components. Aimed at cell phones
and PDAs, the MIC2550 was designed and developed by Micrel
Semiconductor.

The MIC2550 is fully compliant to USB Specification Rev 1.1 and
converts signaling voltages as low as 2.5V to the USB standard of
3.3V. This solves the problem of interfacing USB with today’s
low-voltage, deep submicron ASICs used in cellular phones, PDAs
and other mobile devices.

As OEMs utilize CMOS ASICs with ever-decreasing line widths to
increase integration and lower systems costs, internal operating
voltages are decreasing while the external USB interface voltage
remains the same. Since USB utilizes a standard power bus with
3.3V signaling, it is becoming difficult to directly interface
these standard voltages with fine-line geometry processes, some
of which operate at a 2.5V signaling level.

The MIC2550 currently operates down to 2.5V on the system side
while supporting the 3.3V signaling required by USB. The MIC2550
also integrates a 3.3V low dropout (LDO) regulator to provide the
termination voltage, lowering system costs by eliminating the
need to provide external regulation.

The MIC2550 is designed to connect directly to the USB voltage
and data bus at speeds up to 12Mbs. To support USB suspend
current requirements, it consumes less than 200uA operating
current. For very low current consumption, a suspend control pin
is provided that shuts down the internal amplifier.

The MIC2550BTS is provided in a 14 pin TSSOP package is priced at
$1.90 when purchased in 1,000-piece quantities. Samples are
available now from stock, and production quantities are stock to
8 weeks ARO.

Micrel is a manufacturer of high-performance analog and power ICs
and subminiature packaging. These products include: linear and
switching voltage regulators, PCMCIA and USB power controllers,
operational amplifiers and comparators, voltage references, power
drivers and RF devices.

www.micrel.com/