Datasheet

PCA9512A_PCA9512B All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6 — 1 March 2013 10 of 27
NXP Semiconductors
PCA9512A; PCA9512B
Level shifting hot swappable I
2
C-bus and SMBus bus buffer
8.8 Hot swapping and capacitance buffering application
Figure 7 through Figure 9 illustrate the usage of the PCA9512A 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 time and
fall time requirements difficult to meet. Placing a bus buffer on the edge of each card,
however, isolates the card capacitance from the backplane. For a given I/O card, the
PCA9512A drives the capacitance of everything on the card and the backplane must drive
only 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.
Remark: Application assumes bus capacitance within ‘proper operation’ region of Figure 5 and Figure 6.
Fig 7. Hot swapping multiple I/O cards into a backplane using the PCA9512A in a cPCI, VME, and AdvancedTCA
system
002aab791
R4
10 kΩ
C1
0.01 μF
SDAOUT
SCLOUT
ACC
V
CC2
GND
R5
10 kΩ
R6
10 kΩ
V
CC
SDAIN
SCLIN
POWER SUPPLY
HOT SWAP
CARD1_SDA
CARD1_SCL
STAGGERED CONNECTOR
I/O PERIPHERAL CARD 1
BACKPLANE
CONNECTOR
R2
10 kΩ
R1
10 kΩ
V
CC2
BACKPLANE
BD_SEL
SDA
SCL
V
CC
R3
5.1 Ω
C2 0.01 μF
PCA9512A
R8
10 kΩ
C3
0.01 μF
SDAOUT
SCLOUT
ACC
V
CC2
GND
R9
10 kΩ
R10
10 kΩ
V
CC
SDAIN
SCLIN
POWER SUPPLY
HOT SWAP
CARD2_SDA
CARD2_SCL
STAGGERED CONNECTOR
I/O PERIPHERAL CARD 2
R7
5.1 Ω
C4 0.01 μF
PCA9512A
R12
10 kΩ
C5
0.01 μF
SDAOUT
SCLOUT
ACC
V
CC2
GND
R13
10 kΩ
R14
10 kΩ
V
CC
SDAIN
SCLIN
POWER SUPPLY
HOT SWAP
CARDN_SDA
CARDN_SCL
STAGGERED CONNECTOR
I/O PERIPHERAL CARD N
R11
5.1 Ω
C6 0.01 μF
PCA9512A