LTACF datasheet(12/16 Pages) LINER

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LTC4300A-1/LTC4300A-2

sn4300a12 4300a12fs

APPLICATIO S I FOR ATIO

of the connector and the LTC4300A-2, as shown in the

figure. In addition, make sure that the VCC bypassing on

the backplane is large compared to the 0.01

µF bypass

capacitor on the card. Establishing early power VCC en-

sures that the 1V precharge voltage is present at the

SDAIN and SCLIN pins before they make contact. Connect

VCC2 to the output of one of the CompactPCI power supply

Hot Swap circuits. VCC2 is monitored by a filtered UVLO

circuit. With the VCC2 voltage powering up after all other

pins have established connection, the UVLO circuit en-

sures that the backplane and card data and clock busses

are not connected until the transients associated with live

insertion have settled.

Figure 5 shows the LTC4300A-1 in a PCI application,

where all of the pins have the same length. In this case,

connect an RC series circuit on the I/O card between VCC

and ENABLE. An RC product of 10ms provides a filter to

prevent the LTC4300A-1 from becoming activated until

the transients associated with live insertion have settled.

Figure 5. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4300A-1 in a PCI System

Figure 6 shows the LTC4300A-2 in an application where

the user has a custom connector with pins of three

different lengths available. Making VCC2 the shortest pin

ensures that all other pins are firmly connected before

VCC2 receives any voltage. A filtered UVLO circuit on VCC2

ensures that the VCC2 pin is firmly connected before the

LTC4300A-2 connects the backplane to the card.

Repeater/Bus Extender Application

Users who wish to connect two 2-wire systems sepa-

rated by a distance can do so by connecting two

LTC4300A-1s back-to-back, as shown in Figure 7. The

I2C specification allows for 400pF maximum bus capaci-

tance, severely limiting the length of the bus. The SMBus

specification places no restriction on bus capacitance,

but the limited impedances of devices connected to the

bus require systems to remain small if rise- and fall-time

specifications are to be met. The strong pull-up and pull-

down impedances of the LTC4300A-1 are capable of

100k

ENABLE

SDAIN

SCLIN

VCC

GND

SDAOUT

SCLOUT

READY

ENABLE

SDAIN

SCLIN

VCC

GND

SDAOUT

SCLOUT

READY

4300A-1/2 F05

10k

R10

10k

I/O PERIPHERAL CARD 2

LTC4300A-1

CARD2_SCL

CARD2_SDA

10k

I/O PERIPHERAL CARD 1

LTC4300A-1

C2 0.1

µF

100k

C4 0.1

µF

CARD_SCL

CARD_SDA

10k

VCC

10k

BACKPLANE

CONNECTOR

SDA

SCL

0.01

µF

0.01

µF

10k

•

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