pi5a100 Pericom Semiconductor Corporation, pi5a100 Datasheet - Page 9

• Manufacturer Part Number: pi5a100
• Description: Single Supply, High Speed, Quad Spdt Cmos Analog Switch W/master Enable
• Manufacturer: Pericom Semiconductor Corporation

Applications Information
Overvoltage Protection
Proper power-supply sequencing is recommended for all CMOS
devices. Do not exceed the absolute maximum ratings, because
stresses beyond the listed ratings may cause permanent damage
to the devices. Always sequence V+ on first, followed by V-, and
then logic inputs. If power-supply sequencing is not possible, add
two small signal diodes or two current limiting resistors in series
with the supply pins for overvoltage protection (Figure 8). Adding
diodes reduces the analog signal range, but low switch resistance
and low leakage characteristics are unaffected.
RGB Switch
Figure 9 illustrates a simple low cost RGB switch. The RGB -
to-Composite Decoder produces either NTSC or S-VHS video
from an RGB source. Asingle PI5A100 selects one of the two
video sources to produce either SVHS, Composite or RGB video
outputs. The low insertion loss of the PI5A100 eliminates the need
for expensive input/output buffers.
Figure 9: The single PI5A100 is used to select SVHS, VGA or Composite video outputs.
Composite
Encoder
RGB to
Composite
Sync
C
Y
Select
4
SVGA
R-G-B
Sync
G
R
B
Precision, Wide-Bandwidth, Quad SPDT Analog Switch
PI5A100
+5V
9
Figure 8: Overvoltage protection is accomplished using two ex-
ternal blocking diodes or two current limiting resistors.
G or Composite 0.714V
R or Luma 0.7V
B or Chroma 0.28V
H-Sync-0.3V
V g
NO
Composite
Connector
Positive Supply
Connector
S-Video
V+
V-
Connect or
PS7012H
VGA
COM
PI5A100
08/30/04