Super I/O

Super I/O is a class of I/O controller integrated circuits that began to be used on personal computer motherboards in the late 1980s, originally as add-in cards, later embedded on the motherboards. A super I/O chip combines interfaces for a variety of low-bandwidth devices. Now the I/O controller that combined Super I/O function and Embedded Controller function is called embedded Super I/O.

Functions

The functions below are usually provided by the super I/O if the motherboard has these functions:

A floppy-disk controller
An IEEE 1284-compatible parallel port
One or more 16C550-compatible serial port UART's
Keyboard controller for PS/2 keyboard and/or mouse

Most Super I/O chips include some additional low-speed devices, such as:

Temperature, voltage, and fan speed interface
Connect temperature and voltage sensors via SMBus
Thermal Zone
Chassis intrusion detection
Mainboard power management, including control voltage regulator module
LED management
PWM fan speed control
An IrDA Port controller
A game port
A watchdog timer
A consumer IR receiver
A MIDI port
Some GPIO pins
Legacy Plug and Play or ACPI support for the included devices

By combining many functions in a single chip, the number of parts needed on a motherboard is reduced, thus reducing the cost of production.

History

The original super I/O chips communicated with the central processing unit via the ISA bus. With the evolution away from ISA towards use of the PCI bus, the Super I/O chip was often the biggest remaining reason for continuing inclusion of ISA on the motherboard.
Later super I/O chips use the LPC bus instead of ISA for communication with the central processing unit. This normally occurs through an LPC interface on the Southbridge chip of the motherboard.
Since Intel is replacing the LPC bus with the eSPI bus, super I/O chips that connect to that bus have appeared on the market.
Companies that make super I/O controllers include Nuvoton,, Fintek Inc.,ENE Tech. and Microchip Technology. National Semiconductor used to make super I/O controllers but sold that business to Winbond at 2005, which already had a competing super I/O controller business. In 2008, Winbond then spun off its logic businesses to a wholly owned subsidiary, Nuvoton. SMSC made super I/O chips and then got acquired by Microchip Technology.

Common models

ENE Tech.

Many models are used for laptops with built-in keyboard controllers

KB3930
KB930QF

ITE Inc.

T8510E series

Microchip Technology (SMSC)

Microchip Technology provides Super I/O components with their SCH, MEC and LPC47 series. Here are some examples:

SCH3112
SCH3114
SCH3116
SCH3223

Nuvoton Technology ([Winbond])

NCT6776