Philips Semiconductors

Product data sheet

PCA9512

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 k

Ω

R5

10 k

Ω

POWER SUPPLY

HOT SWAP

I/O PERIPHERAL CARD 1

R6

10 k

Ω

R3 5.1

Ω

C2

0.01

µF

SDAIN

SCLIN

SDAOUT

SCLOUT

ACC

GND

CARD1_SDA

CARD1_SCL

PCA9512

C3

0.01

µF

R8

10 k

Ω

R9

10 k

Ω

POWER SUPPLY

HOT SWAP

I/O PERIPHERAL CARD 2

R10

10 k

Ω

R7 5.1

Ω

C4

0.01

µF

SDAIN

SCLIN

SDAOUT

SCLOUT

ACC

GND

CARD2_SDA

CARD2_SCL

PCA9512

C5

0.01

µF

R12

10 k

Ω

R13

10 k

Ω

POWER SUPPLY

HOT SWAP

I/O PERIPHERAL CARD N

R14

10 k

Ω

C6

0.01

µF

SDAIN

SCLIN

SDAOUT

SCLOUT

ACC

GND

CARDN_SDA

CARDN_SCL

PCA9512

R1

10 k

Ω

R2

10 k

Ω

SDA

SCL

BD_SEL

BACKPLANE

BACKPLANE

CONNECTOR

SW02117

R11 5.1

Ω

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