adg3241bryz-reel7 Analog Devices, Inc., adg3241bryz-reel7 Datasheet - Page 13

• Manufacturer Part Number: adg3241bryz-reel7
• Description: 2.5 V/3.3 V, 1-bit, 2-port Level Translator Bus Switch In Sot-66
• Manufacturer: Analog Devices, Inc.

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
Figure 31, and Figure 33. Therefore 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.
of application.
Figure 34. Location of Bus Switched in a Bus Isolation Application
BUS SWITCH
LOCATION
Figure 33. 3.3 V to 1.8 V Voltage Translation,
LOAD A
1.8V
Figure 35 shows a typical example of this type
V
0V
OUT
LOAD B
CC
SWITCH
INPUT
supply, as shown in
LOAD C
3.3V SUPPLY
SEL = 0V
3.3V
LOAD D
V
IN
BACKPLANE
SEL
Figure 29,
BUS/
= 0 V
Rev. B | Page 13 of 16
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, such as video graphics. Bus switches can have
lower on resistance, smaller on and off channel capacitance, and
thus improved frequency performance over their analog
counterparts.
The bus switch channel itself, consisting solely of an NMOS
switch, limits the operating voltage (see Figure 4 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,
minimum value of the resistor is determined by the current-
sinking capability of the driver.
RAM
CPU
BE should be tied to V
BUS
Figure 35. ADG3241 in a Hot Plug Application
CC
through a pull-up resistor; the
CARD (1)
CARD (2)
PLUG-IN
PLUG-IN
ADG3241
CARD I/O
CARD I/O