LTC4300A-1/LTC4300A-2

11

sn4300a12 4300a12fs

APPLICATIO S I FOR ATIO

these applications, note that if the I/O cards were plugged

directly into the backplane, all of the backplane and card

capacitances would add directly together, making rise- and

fall-time requirements difficult to meet. Placing a

LTC4300A on the edge of each card, however, isolates the

card capacitance from the backplane. For a given I/O card,

the LTC4300A drives the capacitance of everything on the

card and the backplane must drive only the capacitance of

the LTC4300A, which is less than 10pF.

Figure 3 shows the LTC4300A-1 in a CompactPCI

of the CompactPCI power supply Hot Swap circuits. Use

a pull-up resistor to ENABLE for a card side enable/disable.

voltage powering up after all other pins have established

connection, the UVLO circuit ensures that the backplane

and card data and clock busses are not connected until the

transients associated with live insertion have settled. Owing

to their small capacitance, the SDAIN and SCLIN pins cause

minimal disturbance on the backplane busses when they

make contact with the connector.

Figure 4 shows the LTC4300A-2 in a CompactPCI configu-

of the long “early power” pins. Because this power is not

switched, add a 5

Figure 4. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4300A-2 in a CompactPCI System

C1

0.01

µF

C3

0.01

µF

C5

0.01

µF

R13

10k

R12

10k

R14

10k

I/O PERIPHERAL CARD N

SDAIN

SCLIN

U3

LTC4300A-2

GND

CARDN_SCL

CARDN_SDA

SDAOUT

SCLOUT

ACC

SDAIN

SCLIN

GND

SDAOUT

SCLOUT

ACC

SDAIN

SCLIN

GND

SDAOUT

SCLOUT

ACC

4300A-1/2 F04

R9

10k

R8

10k

R10

10k

I/O PERIPHERAL CARD 2

U2

LTC4300A-2

CARD2_SCL

CARD2_SDA

R5

10k

R4

10k

R6

10k

I/O PERIPHERAL CARD 1

U1

LTC4300A-2

C2 0.01

µF

5.1

Ω

CARD_SCL

CARD_SDA

BACKPLANE

BACKPLANE

CONNECTOR

SDA

SCL

BD_SEL

POWER SUPPLY

HOT SWAP

C4 0.01

µF

5.1

Ω

POWER SUPPLY

HOT SWAP

C6 0.01

µF

5.1

Ω

POWER SUPPLY

HOT SWAP

R1

10k

R2

10k

CompactPCI is a trademark of the PCI Industrial Computer Manufacturers Group.