PC I/O & KBC / PC Product Line

IT8781F: Legacy LPC SuperI/O with 4 UARTs supported

The IT8781F is a highly integrated Super I/O using the Low Pin Count
Interface. The IT8781F provides the most commonly used legacy Super I/O
functionality plus the latest Environment Control initiatives, including H/W
Monitor, Fan Speed Controller. The device’s LPC interface complies with Intel
“LPC Interface Specification Rev. 1.1”. The IT8781F is ACPI & LANDesk compliant.

The IT8781F features an enhanced hardware monitor providing 3 thermal inputs
from remote thermal resistors, or thermal diode or diode-connected transistor

The fan speed controller can control up to three fan speeds through three
separate 128 steps of Pulse Width Modulation (PWM) output pins and monitor up to
three FANs’ Tachometer inputs. It also features four 16C550 UARTs, one IEEE 1284
Parallel Port, one Floppy Disk Controller and one Keyboard Controller.

Integrated in the IT8781F are 10 logical devices. One high-performance 2.88MB
floppy disk controller, with digital data separator, supporting two drives in
360K/ 720K/ 1.2M/ 1.44M/ 2.88M format. One multi-mode high-performance parallel
port supporting the bi-directional Standard Parallel Port (SPP), the Enhanced
Parallel Port (EPP V. 1.7 and EPP V. 1.9), and the IEEE 1284 compliant Extended
Capabilities Port (ECP). Four 16C550 standard compatible enhanced UARTs perform
asynchronous communication, and also support an IR interface. The device also
features one fan speed controller which controls three and monitors five fans,
and six GPIO ports controlling up to 42 GPIO pins. The IT8781F also has an
integrated Keyboard Controller.

These 10 logical devices can be individually enabled or disabled via software
configuration registers. The IT8781F utilizes power-saving circuitry to reduce
power consumption, and once a logical device is disabled the inputs are
inhibited with the clock disabled and the outputs are tri-stated. The device
requires a single 24/48 MHz clock input and operates with +5V/3.3V power supply.
The IT8781F is available in 128-pin QFP (Quad Flat Package).