LTACG datasheet(14/16 Pages) LINER

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LTC4300A-1/LTC4300A-2

sn4300a12 4300a12fs

APPLICATIO S I FOR ATIO

meeting rise- and fall-time specifications for one nanofarad

of capacitance, thus allowing much more interconnect

distance. In this situation, the differential ground voltage

between the two systems may limit the allowed distance,

because a valid logic low voltage with respect to the

ground at one end of the system may violate the allowed

VOL specification with respect to the ground at the other

end. In addition, the connection circuitry offset voltages

of the back-to-back LTC4300A-1s add together, directly

contributing to the same problem.

Systems with Disparate Supply Voltages

(LTC4300A-1)

In large 2-wire systems, the VCC voltages seen by devices

at various points in the system can differ by a few hundred

millivolts or more. This situation is well modelled by a

series resistor in the VCC line, as shown in Figure 8. For

proper operation of the LTC4300A-1, make sure that

VCC(BUS) ≥ VCC(LTC4300A) – 0.5V.

5V to 3.3V Level Translator and Power Supply

Redundancy (LTC4300A-2)

Systems requiring different supply voltages for the

backplane side and the card side can use the LTC4300A-2,

as shown in Figure 9. The pull-up resistors on the card side

connect from SDAOUT to SCLOUT to VCC2, and those on

the backplane side connect from SDAIN and SCLIN to VCC.

The LTC4300A-2 functions for voltages ranging from 2.7V

to 5.5V on both VCC and VCC2. There is no constraint on the

voltage magnitudes of VCC and VCC2 with respect to each

other.

This application also provides power supply redundancy.

If the VCC2 voltage falls below its UVLO threshold, the

LTC4300A-2 disconnects the backplane from the card, so

that the backplane can continue to function. If the VCC

voltage falls below its UVLO threshold and the VCC2

voltage remains active, ground the ACC pin to ensure

proper operation.

LTACG Datasheet(PDF) 14 Page - Linear Technology