LTC4311

7

4311fa

The typical configuration for the data bus for a 2-wire bus

chosen carefully. A description of the process for choosing

line to supply a steady state pull-up current if the bus is

at logic zero. This pull-up current is used for slewing the

bus line during the initial portion of the positive transition

in order to activate the LTC4311 pull-up current.

state pull-up current provides the freedom to adjust rise

time versus fall time as well as defining the low state

For I/O stage protection from ESD and high voltage spikes

added to the open drain driver of the bus agents.

Bus

4311 F01

DATA

IN

LTC4311

DYNAMIC

CURRENT

PULL-UP

DATA

OUT

Figure 1. Typical 2-Wire Bus Configuration

APPLICATIONS INFORMATION

Low State Noise Margin

V

R

R

(1)

the open-drain driver.

Initial Slew Rate

The initial slew rate, SR, of the bus is determined by:

SR

=

V

R

(2)

detector threshold (0.5V/μs max), in order to activate the

pull-up current.

t

ln

V

V

⎧

⎨

⎪

⎩⎪

⎫

⎬

⎪

⎭⎪

(3)

t

V

IHMIN

V

CC

•(R

V

ILMAX

V

CC

•(R

⎧

⎨

⎪⎪

⎩

⎪

⎪

⎫

⎬

⎪⎪

⎭

⎪

⎪

(4)

to meet the low state noise margin and all bus timing

requirements.

A discussion of the electrical parameters affected by the