DG642DY Vishay, DG642DY Datasheet - Page 9

• Manufacturer Part Number: DG642DY
• Description: Video Switch ICs SPDT Analog Switch
• Manufacturer: Vishay

Specifications of DG642DY

• Number Of Switches: Single
• On Resistance (max): 8 Ohms
• On Time (max): 100 ns
• Off Time (max): 60 ns
• Supply Voltage (max): 21 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Package / Case: SOIC-8 Narrow
• Maximum Power Dissipation: 300 mW
• Mounting Style: SMD/SMT
• Supply Current: 3.5 mA
• Switch Configuration: SPDT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS
Document Number: 70058
S11-0154-Rev. F, 31-Jan-11
C
C
1
2
= 10 µ F Tantalum
= 0.1 µ F Ceramic
75 
CH
S
S
S
S
1
2
3
4
1
Figure 7. Supply Decoupling
75 
CH
2
75 
- 3 V
V+
V-
CH
DG64X
+ 15 V
C
C
3
1
1
+
+
75 
CH
TTL Channel Select
GNDs
Figure 8. 4 by 1 Video Multiplexing Using the DG641
4
C
C
2
2
D
D
D
D
1
2
3
4
- 3 V
V+
V-
DG641
+ 15 V
Board Layout
PCB layout rules for good high frequency performance must
also be observed to achieve the performance boasted by
these analog switches. Some tips for minimizing stray effects
are:
1.
2.
3.
Figure 8 shows a 4-channel video multiplexer using a
DG641.
In Figure 9, two coax cables terminated on 75  bring two
video signals to the DG642 switch. The two drains tied
together lower the on-state capacitance. An Si582 video
amplifier drives a double terminated 75  cable. The double
terminated coax cable eliminates line reflections.
Use extensive ground planes on double sided PCB,
separating adjacent signal paths. Multilayer PCB is
even better.
Keep signal paths as short as practically possible,
with all channel paths of near equal length.
Careful arrangement of ground connections is also
very important. Star connected system grounds
eliminate signal current, flowing through ground path
parasitic
channels.
250 
DG641, DG642, DG643
+
-
resistance,
A = 2
250 
Si582
DIS
from
Vishay Siliconix
75 
coupling
www.vishay.com
between
9