LTC4314

16

4314f

Figure 10. The LTC4314 Configured as a 2:1 Demultiplexer in a System with Redundancy

LTC4314

GND

4314 F10

SDAIN

SCLIN

ACC

DISCEN

FAULT

SDAOUT1

SCLOUT1

ENABLE1

SDAOUT2

SCLOUT2

ENABLE2

SDAOUT3

SCLOUT3

ENABLE3

SDAOUT4

SCLOUT4

ENABLE4

C1

0.01μF

SDA

SCL

FAULT

3.3V

R9

10k

R8

10k

R1

10k

R2

10k

5V

R3

10k

R4

10k

R5

100k

3.3V

R10

10k

R7

20k

BFP405F

R6

50k

PRIMARY

MASTER

CONTROLLER

CARD

BACKUP

MASTER

CONTROLLER

CARD

APPLICATIONS INFORMATION

Demultiplexer Function

Due to its bi-directional nature, the LTC4314 can be used

as a demultiplexer. This is shown in Figure 10 where two

with redundancy to the slave side. In this application the

SDAOUT/SCLOUT channels serve as the inputs while the

SDAIN/SCLIN channel is the output. Redundancy on the

master side provides protection against power supply

failure. In Figure 10, if the 5V bus supply on channel 1

falls below 1.4V, channel 1 gets disabled as ENABLE1 is

of the pull-down device on ENABLE4 falls below 0.7V and

it turns off. This causes ENABLE4 to be pulled up by R7

which in turn enables channel 4, causing control to be

Hot-Swapping

Figure 11 shows the LTC4314 in a typical hot-swapping

application where the LTC4314 is on the backplane and I/O

cards plug into the downstream channels. The outputs must

idle high and the corresponding output channel must be

disabled before an I/O card can be plugged or unplugged

from an output channel. Figure 11 also shows the use of

noise margin of the LTC4314 supports logic low levels up

logic low levels on the block and data lines.

Level Translating to Bus Voltages < 2.25V

The LTC4314 can be used for level translation to bus volt-

ages below 2.25V if certain conditions are met. In order to

perform this level translation, RTAs on the low voltage side

need to be disabled in order to prevent an over drive of

the low voltage bus. This can be accomplished by forcing

nels is pulled up to the low voltage bus supply, all other

output channels need to be disabled when this channel

is active, in order to prevent cross conduction between

the output channels. Since the buffer turn-on and turn-off

is determined by equation 5:

0.7

(5)

not impact the high side noise margin. Users willing to live

with a lower logic high noise margin can level translate

down to 1.5V. An example of voltage level translation from