DG884AM VISHAY [Vishay Siliconix], DG884AM Datasheet - Page 10

• Manufacturer Part Number: DG884AM
• Description: 8 x 4 Wideband Video Crosspoint Array
• Manufacturer: VISHAY [Vishay Siliconix]

DEVICE DESCRIPTION
The DG884 is the world’s first monolithic wideband crosspoint
array that operates from dc to >100 MHz. The DG884 offers
the ability to route any one of eight input signals to any one of
four OUT pins. Any input can be routed to one, two, three or
four OUTs simultaneously with no risk of shorting inputs
together (guaranteed by design).
Each crosspoint is configured as a “T” switch in which DMOS
FETs are used due to their excellent low resistance and low
capacitance characteristics. Each OUT line has a series
switch that minimizes capacitive loading when the OUT is off.
Interfacing
The DG884 was designed to allow complex matrices to be
developed while maintaining a simple control interface. The
status of the I/O pin determines whether the DG884 is being
written to or read from (see Figures 1 and 2).
In order to WRITE to an individual latch, CS and I/O need to
be low, while RS, WR and SALVO must be high. The IN to OUT
path is selected by using address A
IN line and address B
The IN defined by A
OUT defined by B
Next Event latches when WR goes low and returns high again.
This operation is repeated up to three more times if other
crosspoint connections need to be changed.
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DG884
Vishay Siliconix
1, 3, 4, 6, 8, 10, 12, 14, 16,
5, 7, 9, 11, 13, 15, 17, 19
18, 20, 41, 43
31, 32, 33, 34
22, 23, 24, 25
2, 40, 42, 44
27, 28
Pin
39
26
21
38
29
30
35
36
37
0
0
, B
through A
0
1
and B
. This chosen path is loaded into the
OUT
A
DIS
0
Symbol
IN
, A
SALVO
1
DGND
B
1
1
GND
1
WR
3
1
0
I/O
CS
RS
to define the OUT line. That is,
V+
V−
V
to IN
to OUT
to DIS
, A
, B
L
is electrically connected to the
2
1
, A
8
0
4
3
4
through A
Analog Signal Ground
Digital Ground
Positive Supply Voltage
Negative Supply Voltage
Logic Supply Voltage—generally 5 V
8 Analog Input Channels
4 Analog Output Channels
Determines whether data is being written into the Next Event latches or read from the Current Event latches
Chip Select—a logic input
IN Address—logic inputs or outputs as defined by I/O pin, select one of eight IN channels
OUT Address—logic inputs, select one of four OUT channels
Write command that latches A
Master write command, that in one action, transfers all the data from Next Event latches into
Current Event latches
Reset—a low will clear the Current Event latches
Open drain disable outputs—these outputs pull low when the corresponding OUT channel is off
3
to define the
PIN DESCRIPTION
0
, A
1
Upon completing all crosspoint connections that are to be
changed in a single device, other DG884s can be similarly
preset by taking the CS pin low on the appropriate device.
When all DG884s are preset, the Current Event latches are
simultaneously changed by a single SALVO command applied
to all devices. In this manner the crosspoint configuration of
any number of devices can be simultaneously updated.
DIS Outputs
Four open drain disable OUTs are provided to control external
line drivers or to provide visual or electrical signaling. For
example, any or all of the DIS OUTs can directly interface with
a CLC410 Video Amplifier to place it into a high impedance,
low-power standby mode when the corresponding OUT is not
being used. (See Figure 15). The DIS outputs are low and sink
to V− when corresponding OUT is open or RS is low.
Reset
The reset function (RS) allows the resetting of all crosspoints
to a known state (open). At power up, the reset facility may be
used to guarantee that all switches are open. It should be
noted that RS clears the Current Event latches, but the Next
Event latches remain unchanged. This useful facility allows
the user to return the matrix to its previous state (prior to reset)
by simply applying the SALVO command. Alternatively, the
user can reprogram the Next Event latches, and then apply the
SALVO command to reconfigure the matrix to a new state.
, A
2
, A
3
into the Next Event latches
Description
S-52433—Rev. G, 20-Dec-04
Document Number: 70071