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www.fairchildsemi.com

www.fairchildsemi.com

FM3540/60 Rev. C

FM3540/60

4/5 Bit Multiplexed, 1 Bit Latched Port with Standard

2-Wire Bus Interface and Non-Volatile Latches

General Description

The FM3540/60 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 supports

a choice of either 2.5V output or Open Drain Outputs for easy

interface to devices with different VDD Levels.

The serial port is an IIC compatible slave only interface and

supports both 100kbits and 400kbits modes of operation. The port

is used to read the I-Port, Write Data to the internal non-volatile

Block Diagram

October 2001

registers and select whether the I-Port or one of the internal non-

volatile registers is output to the Y-port. The FM3540/60 is

fabricated with an advanced CMOS technology to achieve high

density and low power.

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

© 2001 Fairchild Semiconductor Corporation

SOPRA

SOPRB

IIC

Interface

Start/Stop

Logic

Shift

Register

Slave Address

Register

Comparator

Control Logic

Mux3

Mux2

Non_Mux_Out

Y[4:0]

I[4:0]

IIC Read Logic

SDA

SCL

ASEL

OVRD

MUXSEL

MXSB, MXSA

Mux1