Philips Semiconductors Product data sheet
PCA9512Level shifting hot swappable I
2
C and SMBus buffer
2004 Oct 05
7
Hot Swapping and Capacitance Buffering
Application
Figures 7 through 9 illustrate the usage of the PCA9512 in
applications that take advantage of both its hot swapping and
capacitance buffering features. In all of 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
PCA9512 on the edge of each card, however, isolates the card
capacitance from the backplane. For a given I/O card, the PCA9512
drives the capacitance of everything on the card and the backplane
must drive only the the capacitance of the bus buffer, which is less
than 10 pF, the connector, trace, and all additional cards on the
backplane.
See Application Note
AN10160, Hot Swap Bus Buffer
for more
information on applications and technical assistance.
C1
0.01 µF
R4
10 kΩ
R5
10 kΩ
POWER SUPPLY
HOT SWAP
I/O PERIPHERAL CARD 1
R6
10 kΩ
R3 5.1 Ω
C2
0.01 µF
V
CC
V
CC2
SDAIN
SCLIN
SDAOUT
SCLOUT
ACC
GND
CARD1_SDA
CARD1_SCL
PCA9512
C3
0.01 µF
R8
10 kΩ
R9
10 kΩ
POWER SUPPLY
HOT SWAP
I/O PERIPHERAL CARD 2
R10
10 k
Ω
R7 5.1 Ω
C4
0.01 µF
V
CC
V
CC2
SDAIN
SCLIN
SDAOUT
SCLOUT
ACC
GND
CARD2_SDA
CARD2_SCL
PCA9512
C5
0.01 µF
R12
10 kΩ
R13
10 kΩ
POWER SUPPLY
HOT SWAP
I/O PERIPHERAL CARD N
R14
10 kΩ
C6
0.01 µF
V
CC
V
CC2
SDAIN
SCLIN
SDAOUT
SCLOUT
ACC
GND
CARDN_SDA
CARDN_SCL
PCA9512
R1
10 kΩ
R2
10 kΩ
V
CC2
V
CC
SDA
SCL
BD_SEL
BACKPLANE
BACKPLANE
CONNECTOR
SW02117
R11 5.1 Ω
STAGGERED CONNECTORSTAGGERED CONNECTORSTAGGERED CONNECTOR
NOTE: Application assumes bus capacitance within “proper operation” region of Figures 5 and 6.
Figure 7. Hot swapping multiple I/O cards into a backplane using the PCA9512 in a CompactPCI, VME, and AdvancedTCA system
