FM3570 Datasheet, PDF (1/8 Pages) Fairchild Semiconductor – CPU CONFIGURATION CONTROLLER Register/Multiplexer for Microprocessor VID

Preliminary
March 2001
FM3570
CPU CONFIGURATION CONTROLLER
Register/Multiplexer for Microprocessor VID
General Description
The Fairchild FM3570 replaces the CPU motherboard’s configu-
ration switches with an electronic implementation consisting of a
4/5-bit multiplexed, 1-bit latched port, standard 2-wire bus inter-
face, and non-volatile latches.
The FM3570 multiplexes the I-port input signals with two internal
non-volatile registers that can be loaded through the serial port.
The multiplexer is selected via the serial port and defaults to the
I-port upon power-up. 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, write data to the internal non-volatile
registers and select whether the I-port or one of the internal non-
volatile registers is output to the Y-port. The FM3570 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 Choice of 2.5V Outputs or Open-Drain Outputs
Block Diagram
Non_Mux_Out
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
MUXSEL
OVRD
Slave Address
Register
Comparator
ASEL
© 2001 Fairchild Semiconductor Corporation
1
FM3570 Rev. A
www.fairchildsemi.com