ADG3241 AD [Analog Devices], ADG3241 Datasheet - Page 10

• Manufacturer Part Number: ADG3241
• Description: 2.5 V/3.3 V, 1-Bit, 2-Port Level Translator Bus Switch in SOT-66
• Manufacturer: AD [Analog Devices]

ADG3241
Bus Isolation
A common requirement of bus architectures is low capacitance
loading of the bus. Such systems require bus bridge devices that
extend the number of loads on the bus without exceeding the
specifications. Because the ADG3241 is designed specifically for
applications that do not need drive yet require simple logic
functions, it solves this requirement. The device isolates access
to the bus, thus minimizing capacitance loading.
Hot Plug and Hot Swap Isolation
The ADG3241 is suitable for hot swap and hot plug applications.
The output signal of the ADG3241 is limited to a voltage that is
below the V
the switch acts like a buffer to take the impact from hot insertion,
protecting vital and expensive chipsets from damage.
In hot plug applications, the system cannot be shut down when
new hardware is being added. To overcome this, a bus switch can
be positioned on the backplane between the bus devices and the
hot plug connectors. The bus switch is turned off during hot plug.
Figure 12 shows a typical example of this type of application.
Figure 11. Location of Bus Switched in a Bus
Isolation Application
RAM
CPU
Figure 12. ADG3241 in a Hot Plug Application
BUS SWITCH
LOCATION
CC
supply, as shown in Figures 6, 8, and 10. Therefore
LOAD A
LOAD B
LOAD C
PLUG-IN
CARD (1)
PLUG-IN
CARD (2)
LOAD D
BACKPLANE
BUS/
CARD I/O
CARD I/O
–10–
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, BE should be tied to V
minimum value of the resistor is determined by the current-
sinking capability of the driver.
CC
through a pull-up resistor; the
REV. A