User guide

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64
Output
timing
The signals A0-A3 and CSxx are used to address the multiplexor
circuits.
The cycle time will vary depending on the refresh rate of the
received DMX512.
Device
Operation
The AL4020 operates in two distinct modes:
• Analogue to DMX512 Conversion.
• Analogue and DMX512 Merge.
Analogue to
DMX512
Conversion
The address wheels are set to 000 in order to enable Analogue to
DMX512 conversion. In this mode, the DMX512 input is ignored and
the received data indicator does not illuminate.
The DMX512 output transmits 512 channels of which the first 72
represent the analogue inputs.
Analogue
and
DMX512
Merge
The BCD inputs are set to a value in the range 001 to 512 in order to
enable Analogue and DMX512 merge. In this mode, the DMX512 input
and the analogue inputs are combined in a highest takes precedence
form.
The BCD inputs set the channel address at which the analogue inputs
are added to the DMX512 input.
Power
Supply
The AL4020 requires a 5V DC supply at approximately 6mA
All Ground and Vcc pins must be connected.
The device is CMOS so normal handling precautions should be
adhered to.
Good decoupling and pcb layout conventions (i.e. fill all unused pcb
areas with grounded copper planes) should be followed.
Particular attention should be paid to routing the crystal
connections.
CS0
A3
A2
A1
A0
Channel 3 - Analogue Input