REV. 0

ADG3243

–9–

PLUG-IN

CARD (1)

CARD I/O

BUS

CARD I/O

RAM

CPU

PLUG-IN

CARD (2)

Figure 10. ADG3243 in a Hot Plug Application

There are many systems, such as docking stations, PCI boards

for servers, and line cards for telecommunications switches, that

require the ability to handle hot swapping. If the bus can be

isolated prior to insertion or removal, there is more control over

the hot swap event. This isolation can be achieved using bus

switches. The bus switches are positioned on the hot swap card

between the connector and the devices. During hot swap, the

ground pin of the hot swap card must connect to the ground pin

of the backplane before any other signal or power pins.

Analog Switching

Bus switches can be used in many analog switching applications,

for example, video graphics. Bus switches can have lower on

resistance, smaller ON and OFF channel capacitance, and thus

improved frequency performance than their analog counterparts.

The bus switch channel itself, consisting solely of an NMOS

switch, limits the operating voltage (see TPC 1 for a typical

plot), but in many cases, this does not present an issue.

High Impedance during Power-Up/Power-Down

To ensure the high impedance state during power-up or power-

down,

BEx should be tied to V

minimum value of the resistor is determined by the current-

sinking capability of the driver.