currently I'am working with the ADM2914 evalboard and wanted to test the function of the ADM2914. I red the schematic and the user guide, but i have no idea how to test the functions of OV and UV. You can set a bunch of voltages which are configurable and see at the TP of UV/OP how the resistor devider works, but how can I cause an OV or UV event and see if the ADM2914 is working properly?
Good day! Sorry to keep you waiting. Thanks for your interest on ADI products.
The four (4) positive inputs are adjustable through the corresponding variable resistors (VR). At first, set the nominal voltage of each positive output by monitoring the corresponding TP while trimming through the VR until the nominal value is set. When all set to nominal, the UV and OV LEDs are not lit.
The UV and OV LEDs lit respectively only when there is an undervoltage and/or overvoltage condition on any output. That is, when a VR is trimmed which causes the corresponding output to be UV or OV. You will see on the schematic that each VR belongs to the bottom of the output resistor divider of each regulator providing the input to the ADM2914; trimming the VR changes the output voltage. Remember that the UV/OV trip points depend on the three external resistors connected to the monitoring pins.
The discussions on pages 9, 10 and 11 of the ADM2914 datasheet should be helpful. Please take a look at the equations involved and contrast with the components on the schematic and the bill of materials in the user guide.
Please let me know if you have question.
thanks for your reply. How do i enable the monitoring? First I need to set the nominal voltage via VR, i know. But when i finished that step and then tuning VR again to cause an UV/OB condition how do the ADM knows that I dont' change the nominal voltage again? Do i have to use some switchen on the eval-board for that?
Did you see any of the LEDs lighting when you tune an output voltage?
You need a voltmeter to monitor each of the output voltages via the corresponding test points.
You can also monitor the corresponding VHx and VLx test points and see if each exceed the 0.5V threshold. For instance, if VL1 exceeds 0.5V, the OV LED is lit; otherwise, if VH1 exceeds 0.5V, the UV LED is lit.
But please remember that only one of the VHx and VLx should exceed 0.5V at a time as OV and UV can not happen simultaneously on an output.
The UV and OV trip points again depend on the external resistors. The discussion and equations on page 9 of the data sheet should be helpful for knowing the trip points. You can vary the trip points by changing the external resistors.
Please see figure below for the respective test points.