PCA9512 Philips Semiconductors, PCA9512 Datasheet - Page 7

• Manufacturer Part Number: PCA9512
• Description: Level shifting hot swappable I2C and SMBus buffer
• Manufacturer: Philips Semiconductors

Philips Semiconductors
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
NOTE: Application assumes bus capacitance within “proper operation” region of Figures 5 and 6.
2004 Oct 05
BD_SEL
Figure 7. Hot swapping multiple I/O cards into a backplane using the PCA9512 in a CompactPCI, VME, and AdvancedTCA system
Level shifting hot swappable I
V
SDA
SCL
10 k
V
CC2
CC
R1
BACKPLANE
R2
10 k
CONNECTOR
BACKPLANE
2
C and SMBus buffer
R3 5.1
R7 5.1
R11 5.1
0.01 F
0.01 F
0.01 F
POWER SUPPLY
POWER SUPPLY
POWER SUPPLY
7
HOT SWAP
C2
HOT SWAP
C4
HOT SWAP
C6
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.
V
SDAIN
SCLIN
V
SDAIN
SCLIN
V
SDAIN
SCLIN
CC
CC
CC
PCA9512
PCA9512
PCA9512
I/O PERIPHERAL CARD 1
I/O PERIPHERAL CARD 2
I/O PERIPHERAL CARD N
V
V
V
GND
GND
GND
CC2
CC2
CC2
0.01 F
0.01 F
0.01 F
C1
C3
C5
SDAOUT
SDAOUT
SDAOUT
SCLOUT
SCLOUT
SCLOUT
ACC
ACC
ACC
R4
10 k
R8
10 k
R12
10 k
10 k
10 k
10 k
R5
R9
R13
PCA9512
Product data sheet
10 k
10 k
10 k
R6
R10
R14
CARD1_SDA
CARD1_SCL
CARD2_SDA
CARD2_SCL
CARDN_SDA
CARDN_SCL
SW02117