USER’S MANUAL
AN1235
Rev 0.00
Feb 2, 2006
ISL59481EVAL1
Evaluation Board User’s Guide
AN1235 Rev 0.00
Page 1 of 7
Feb 2, 2006
Introduction
The ISL59481EVAL1 evaluation board contains the ISL59481
Dual 4:1 RGB MUX amp and associated components needed
to implement an 8:1 RGB+H/V sync video multiplexer. The 8
video input ports, and single output port are accessed using
standard 15 pin VGA female connectors. The I/O connectors
are compatible with most VGA, SVGA and XGA video
sources and video monitors with VGA cable interfaces. A
typical application would use the ISL59481EVAL1 board to
multiplex anywhere from 2 to 8 PC’s or laptops to a single
video monitor or projector.
Evaluation Board Description and Key Features
The multiplexing of the RGB video is performed by the
ISL59481. Multiplexing the H and V sync signals is
accomplished using two ISL84051 8:1 analog switches. The
ISL59481 Video MUX and the analog H and V sync
multiplexers have the same input channel select logic
coding, and are parallel-connected to form a single 3 input
binary coded interface (S0, S1, S2). The evaluation board
contains three different channel select options via jumpers
on the board. Switches on the board enable direct logic
control in binary format. The on-board oscillator and 4-bit
counter can be connected to provide a continuous channel-
by-channel scan of as few as 2 input channels up to all 8. An
added option allows the user to disconnect the auto-scan
oscillator and use the on-board momentary-contact switch to
manually scan through the selected channels.
Reference Documents
• ISL59481 Data Sheet, FN7456
Getting Started
The evaluation board should have the same appearance as
the silk screen shown in Figure 1. Prior to applying power,
connect the source input VGA cables and the evaluation
board output VGA cable to the respective video
components. The evaluation board, as supplied, is designed
for 75
source impedances and requires a 75
termination
impedance in the output display device.
Applying Power to the Evaluation Board
The following safeguards will ensure correct power-up.
1. Limit the current on ±5V supplies to 250mA.
2. Turn on the power supplies after the power cables are
attached to the evaluation board.
Power supply protection Schottky diodes are included on the
±5V supplies to prevent damage due to reverse polarity.
Evaluation Board Jumper, Cable Header, and Switch Descriptions
COMPONENT
DESCRIPTION
JUMPERS
J1
Selects channel select via single-step momentary contact switch S4, or auto mode using on-board oscillator
J-S0
Selects S0 logic input to manual control via switch S0 or through external control ribbon cable header
J-S1
Selects S1 logic input to manual control via switch S1 or through external control ribbon cable header
J-S2
Selects S2 logic input to manual control via switch S2 or through external control ribbon cable header
HEADERS
EN
External MUX enable: Internal pull-down (logic 0) enables RGB+H/V output, logic high disables RGB and H/V sync output
S0
External S0 channel select logic input
S1
External S1 channel select logic input
S2
External S2 channel select logic input
SWITCHES
S0
Manual channel select logic input S0
S1
Manual channel select logic input S1
S2
Manual channel select logic input S2
S3
Momentary contact channel select step control
