70 Application Programs
Application 1. Sequencing Multiple Modules During Power Up
Overview of Application
When testing mixed signal devices, ± bias supply voltages are typically applied before logic bias supply voltages. For a
device that is sensitive to when bias voltages are applied, the order of power up of multiple power modules can be
controlled.
For this example, the device requires three bias supplies, + 5 V for the logic circuits and ± 15 V for amplifier circuits. To
properly power up the device, the supplies must be sequenced so that the ± 15 V are applied first and the + 5 V is applied 50
ms later.
The MPS can easily address this application through the use of triggers. The trigger will cause the modules to change from
0 V, where they are not powering the DUT, to their final voltage. By delaying the response to the trigger, you can control
when the module's output voltage changes. This means you can control the sequence of the modules during power up.
MPS Features Used
• Change the voltage on trigger.
• Trigger in/out from MPS mainframe backplane TTL Trigger.
• Trigger on a GPIB trigger command Trigger delay.
• Trigger delay.
Advantages/Benefits Of The MPS Solution
By using trigger delay, the timing is accurate and repeatable.
The sequence is simpler to program (no timing loops).
The computer is not devoted to sequencing power modules.
The computer does not provide timing for the sequence.
One command initiates the sequence.
Implementation Details
How the MPS Implements The Sequence
The computer sends a trigger command to the first module.
The first module simultaneously sends a backplane trigger to other two modules and goes to + 15 V.
The second module receives the backplane TTL Trigger and immediately goes to - 15 V.
The third module receives the backplane TTL Trigger, delays 50 ms, and then goes to + 5 V.
MPS Set Up
Module in slot 0:
The module is connected to + 15 V on the DUT.
The initial voltage setting is 0 V.
The module listens for the computer to send a trigger command.
Upon receipt of the trigger command, the module goes to 15 V.
Also upon receipt of the trigger command, the module generates a backplane TTL Trigger.
Module in slot 1:
The module is connected to - 15 V on the DUT.
The initial voltage setting is 0 V.
The module listens for a backplane TTL Trigger.
Upon receipt of the trigger, the module goes to 15 V.