LTC4307

10

4307f

Live Insertion and Capacitance Buffering Application

Figures 4 and 5 illustrate applications of the LTC4307 that

buffering and precharge features. If the I/O cards were

plugged directly into the backplane without the LTC4307

buffer, all of the backplane and card capacitances would

add directly together, making rise-time and fall-time re-

quirements difficult to meet. Placing an LTC4307 on the

edge of each card, however, isolates the card capacitance

from the backplane. For a given I/O card, the LTC4307

drives the capacitance of everything on the card and the

backplane must drive only the capacitance of the LTC4307,

which is less than 10pF.

In most applications the LTC4307 will be used with a

pins. SDA and SCL are medium length pins to ensure that

the precharge circuitry to be activated on SDA and SCL

before they make contact. ENABLE is a short pin that is

pulled down when not connected. This is to ensure that

the connection between the backplane and the card’s data

and clock busses is not is not enabled until the transients

associated with live insertion have settled.

Figure 4 shows the LTC4307 in an application with a stag-

from one of the long “early power” pins. Establishing

present at SDAIN and SCLIN before they make contact.

Figure 4. The LTC4307 in an Application with a Staggered Connector

Hot Swap is a trademark of Linear Technology Corporation.

C1

0.01

μF

I/O PERIPHERAL CARD 1

CARD

CONNECTORS

BACKPLANE

CONNECTOR

BACKPLANE

R5

10k

R4

10k

SDAIN

SCLIN

ENABLE

READY

SDAOUT

SCLOUT

GND

LTC4307

R3

10k

R2

10k

R1

10k

ENAn

SDA

SCL

ENA1

READY

R6

10k

CARD1_SDA

CARD1_SCL

C2

0.01

μF

I/O PERIPHERAL CARD N

R8

10k

R7

10k

4307 F04

SDAIN

SCLIN

ENABLE

READY

SDAOUT

SCLOUT

GND

LTC4307

R9

10k

CARDn_SDA

CARDn_SCL

•

•

•

APPLICATIONS INFORMATION