LTC4310IMS-2#TRPBF Linear Technology, LTC4310IMS-2#TRPBF Datasheet - Page 13

• Manufacturer Part Number: LTC4310IMS-2#TRPBF
• Description: IC I2C ISOLATR 400KHZ BUS 10MSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap I²C Isolatorsr

Specifications of LTC4310IMS-2#TRPBF

• Tx/rx Type: I²C Logic
• Capacitance - Input: 10pF
• Voltage - Supply: 3 V ~ 5.5 V
• Current - Supply: 7mA
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Delay Time: -

applicaTions inForMaTion
Once a STOP bit or bus idle occurs on both the local and
isolated buses, the LTC4310 reactivates its buffers and
rise time accelerators.
READY Digital Output
The READY pin provides a digital output flag that pulls
low to indicate that the LTC4310 is driving its SDA and
SCL pins with the logic state information it is receiving on
its RXP and RXN pins from the other LTC4310. READY is
driven by an N-channel MOSFET open-drain pull-down that
is capable of sinking 4mA while holding 0.4V maximum.
The pull-down turns off whenever the LTC4310 is not
driving its SDA and SCL pins—during start-up, thermal
shutdown, low current shutdown and after disconnection
due to a stuck bus or failure to receive a transmission
within 4.6ms. Connect a resistor to the bus pull-up supply
to provide the pull-up.
Design Example: High Voltage Isolation Using an
Inexpensive Ethernet Transformer
Figure 1 shows the LTC4310-1 providing I
cations between two buses whose ground voltages can
C
µP
BUS
= 40pF
3.3V
SLAVE
R1
4.3k
R2
4.3k
SCL1
C1
0.01µF
V CC
EN
SDA
SCL
LTC4310-2
GND
READY
RXN
RXP
TXP
TXN
Figure 7. The LTC4310-2 in a 400kHz Application
2
R3
10k
C communi-
C2
0.01µF
1
3
6
7
8
TRANSFORMER
10/100Base-TX
ETHERNET
EPF8119S
16
15
14
11
9
differ up to 1500V. An EPF8119S Ethernet transformer is
used to bridge the isolation barrier. The left I
nects to the LTC4310-1 and two other devices, resulting
in a bus parasitic capacitance of 40pF in this example
set-up. Referring to the V
7.5k pull-up resistors are chosen for R1 and R2. The right
I
devices, resulting in a bus parasitic capacitance of 80pF .
Referring to the V
resistors are also chosen for R5 and R6. Standard 5%
resistors are used.
Sudden changes in the ground differential across the
isolation barrier can be effectively resisted by tying the
center tap of the receive side of the transformer to the
local ground through a 0.01µF capacitor, as shown by
capacitors C2 and C3.
Figure 7 shows the same application as Figure 1, but with
each LTC4310-1 replaced by an LTC4310-2, so that the
bus can switch at frequencies up to 400kHz. To meet the
requirements shown in the curves of Figure 3, R1 and R2
are changed from 7.5k to 4.3k, and R5 and R6 are changed
from 7.5k to 3.3k.
2
C bus connects to another LTC4310-1 and four slave
C3
0.01µF
R4
10k
READY
RXP
RXN
TXP
TXN
LTC4310-2
LTC4310-1/LTC4310-2
GND
SDA
V CC
SCL
EN
CC
431012 F07
= 5V curve in Figure 2, 7.5k pull-up
SCL2
C4
0.01µF
CC
= 3.3V curve in Figure 2,
R5
3.3k
SLAVE#1
R6
3.3k
IS0LATED
5V
C
BUS
2
. . .
C bus con-
= 80pF
SLAVE#4

431012f