LTC4311CSC6#TRPBF Linear Technology, LTC4311CSC6#TRPBF Datasheet - Page 7

• Manufacturer Part Number: LTC4311CSC6#TRPBF
• Description: IC ACCELERATOR SMBUS DL SC70-6
• Manufacturer: Linear Technology
• Type: Acceleratorr

Specifications of LTC4311CSC6#TRPBF

• Tx/rx Type: I²C Logic
• Voltage - Supply: 1.6 V ~ 5.5 V
• Current - Supply: 300µA
• Mounting Type: Surface Mount
• Package / Case: SC-70-6, SC-88, SOT-363
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Delay Time: -
• Capacitance - Input: -

APPLICATIONS INFORMATION
Selecting the values of R
The typical confi guration for the data bus for a 2-wire bus
is shown in Figure 1. The parameters R
chosen carefully. A description of the process for choosing
the values of R
An external pull-up resistor R
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.
Using an external pull-up resistor R
state pull-up current provides the freedom to adjust rise
time versus fall time as well as defi ning the low state
logic-level (V
For I/O stage protection from ESD and high voltage spikes
on the bus, a series resistor R
added to the open drain driver of the bus agents.
Both the values of R
to meet the low state noise margin and all bus timing
requirements.
A discussion of the electrical parameters affected by the
values of R
selecting the values of R
Figure 1. Typical 2-Wire Bus Confi guration
S
and R
OL
CURRENT
DYNAMIC
PULL-UP
LTC4311
P
).
and R
V
P
CC
, as well as the general procedure for
P
S
and R
DATA
DATA
follows.
OUT
S
IN
S
and R
and R
S
C
BUS
P
S
must be chosen carefully
P
(Figure 1) is sometimes
is required in each bus
P
follows.
R
R
R
P
S
ON
P
P
Bus
to supply steady
and R
4311 F01
S
should be
Low State Noise Margin
A low value of V
for good noise margin. V
R
the open-drain driver.
Increasing the value of R
Increasing R
Initial Slew Rate
The initial slew rate, SR, of the bus is determined by:
SR must be greater than SR
detector threshold (0.5V/μs max), in order to activate the
pull-up current.
I
Rise time of an I
Fall time of an I
where R
2
L
C Rise and Fall Time
ln
V
SR =
t
t
is the series sum of R
r
f
OL
⎧
⎪
⎨
⎩ ⎪
= – R
= R
V
V
=
ILMAX
IHMIN
T
R
V
R
T
R
is the parallel equivalent of R
CC
P
L
• C
L
p
• C
• V
L
+ R
– V
• C
BUS
– V
increases the value of V
– V
BUS
2
CC
BUS
OL
P
2
C line is derived using equation 4.
OL
CC
C line is derived using equation 3.
CC
• ln
, the low state logic level, is desired
•
– R
– R
⎧
⎪ ⎪
⎨
⎪
⎪
⎩
p
V
p
V
ILMAX
•I
IHMIN
S
•I
V
V
P
CC
CC
and R
THRESH
PULLUP AC
OL
PULLUP AC
decreases the value of V
is calculated as follows:
•(R
•(R
ON
, the LTC4311 slew rate
P
P
, the on resistance of
+ R
+ R
⎫
⎪
⎬
⎭ ⎪
OL
P
LTC4311
L
L
.
and R
) – R
) – R
L
L
L
.
⎫
⎪ ⎪
⎬
⎪
⎪
⎭
4311fa
7
(1)
(2)
(4)
OL
(3)
.