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 (2N3904).
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 2.88 MB 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).
