FM3565 Datasheet, PDF (1/7 Pages) Fairchild Semiconductor – CPU CONFIGURATION CONTROLLER Register/Multiplexer for Microprocessor VID

Preliminary
March 2001
FM3565
CPU CONFIGURATION CONTROLLER
Register/Multiplexer for Microprocessor VID
General Description
The Fairchild FM3565 replaces the PC motherboard’s CPU
configuration switches with an electronic implementation, consist-
ing of a 5-bit multiplexed port, standard 2-wire bus interface, and
non-volatile latches with external hardware control.
The FM3565 multiplexes the I-port input signals with two internal
non-volatile registers that can be loaded through the serial port.
The multiplexer output is under hardware control, and is deter-
mined by the inputs OVRD, MUXSEL, and A/B. Pull-up resistors
are provided on the input port to accommodate connections to
open drain outputs and to eliminate the need for external resistors.
The device has open-drain outputs for easy interface to devices
with different V_DD Levels.
The serial port is an IIC compatible slave-only interface and
supports both 100kbit and 400kbit modes of operation. The port
is used to read the I-Port and to write data to the internal non-
volatile registers. The FM3565 is fabricated with advanced CMOS
technology to achieve high density and low power operation.
Features
I Extended Operating Voltage Range 3.0V-5.5V
I IIC Compatible Slave Interface.
I ESD performance: Human body model > 2000V
I Open-Drain Outputs
Block Diagram
I [4:0]
SOPRA
SOPRB
IIC Read Logic
Mux3
SDA
SCL
IIC
Interface
Start/Stop
Logic
Shift
Register
Mux2
MXSB, MXSA
Y [4:0]
Mux1
Control Logic
Slave Address
Register
Comparator
MUXSEL
A/B
OVRD
ASEL
© 2001 Fairchild Semiconductor Corporation
1
FM3565 Rev. A.1
www.fairchildsemi.com