DG884AM VISHAY [Vishay Siliconix], DG884AM Datasheet - Page 12

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

Power Supplies and Decoupling
A useful feature of the DG884 is its power supply flexibility. It
can be operated from dual supplies, or a single positive supply
(V− connected to 0 V) if required. Allowable operating voltage
ranges are shown in Operating Voltage Range (Typical
Characteristics) graph, page 6.
Note that the analog signal must not go below V− by more than
0.3 V (see absolute maximum ratings). However, the addition
of a V− pin has a number of advantages:
1)
2)
3)
It is established RF design practice to incorporate sufficient
bypass capacitors in the circuit to decouple the power supplies
to all active devices in the circuit. The dynamic performance
www.vishay.com
12
DG884
Vishay Siliconix
APPLICATIONS
It allows flexibility in analog signal handling, i.e. with
V− = −5 V and V+ = 15 V, up to "5-V ac signals can be
accepted.
The value of on-capacitance [C
by increasing the value of V−. It is useful to note that
optimum video differential phase and gain occur when
V− is −3 V. Note that V+ has no effect on C
V− eliminates the need to bias an ac analog signal
using potential dividers and large decoupling capaci-
tors.
FIGURE 14. DG884 Power Supply Decoupling
C
2
51 W
C
+
+5 V
1
V
DG884
L
V−
C
−3 V
+
+15 V
51 W
1
V+
C
+
1
51 W
C
2
C
C
C
S(on)
2
1
2
= 1 mF Tantalum
= 100 nF Ceramic
] may be reduced
S(on)
.
of the DG884 is adversely affected by poor decoupling of
power supply pins. Also, since the substrate of the device is
connected to the negative supply, proper decoupling of this pin
is essential.
Rules:
1)
2)
3)
Recommended decoupling capacitors are 1- to 10-mF
tantalum bead, in parallel with 100-nF monolithic ceramic.
4)
The V
is primarily designed to be TTL or CMOS logic compatible with
+5 V applied to V
simply by increasing V
Decoupling capacitors should be incorporated on all
power supply pins (V+, V−, V
They should be mounted as close as possible to the
device pins.
Capacitors should have good high frequency charac-
teristics—tantalum bead and/or monolithic ceramic
disc types are suitable.
Additional high frequency protection may be provided
by 51-W carbon film resistors connected in series with
the power supply pins (see Figure 14).
L
pin permits interface to various logic types. The device
FIGURE 15. Switching Threshold Voltage vs. V
6
5
4
3
2
1
0
0
2
L
. The actual logic threshold can be raised
4
L
.
V
6
L
− Logic Supply (V)
8
10
L
).
S-52433—Rev. G, 20-Dec-04
Document Number: 70071
12
14
16
L
18