Manualshelf

Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsInterface ICsInterface IC - buffer amplifiers, accelerators I²C hot swap 400 kHz MSOP 8
12345678910
LTC4307
10
4307f
Live Insertion and Capacitance Buffering Application
Figures 4 and 5 illustrate applications of the LTC4307 that
take advantage of the LTC4307’s Hot Swap
TM
, capacitance
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 diffi cult 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
staggered connector where V
CC
and GND will be long
pins. SDA and SCL are medium length pins to ensure that
the V
CC
and GND pins make contact fi rst. This will allow
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-
gered connector. The LTC4307 receives its V
CC
voltage
from one of the long “early power” pins. Establishing
early power V
CC
ensures that the 1V precharge voltage is
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
0.01μF
I/O PERIPHERAL CARD 1
CARD
CONNECTORS
BACKPLANE
CONNECTOR
BACKPLANE
R5
10k
R4
10k
SDAIN
SCLIN
ENABLE
READY
SDAOUT
SCLOUT
V
CC
GND
LTC4307
R3
10k
R2
10k
R1
10k
V
CC
ENAn
SDA
SCL
ENA1
READY
R6
10k
CARD1_SDA
CARD1_SCL
C2
0.01μF
I/O PERIPHERAL CARD N
R8
10k
R7
10k
4307 F04
SDAIN
SCLIN
ENABLE
READY
SDAOUT
SCLOUT
V
CC
GND
LTC4307
R9
10k
CARDn_SDA
CARDn_SCL
•
•
•
APPLICATIONS INFORMATION