One of the main application of high voltage resistor dividers is in power supplies with a feedback loop for regulation purposes. Appropriate choice of resistor values and their ratio determines the feedback voltage. For optimal performance a primary high voltage resistor is often combined with a secondary low voltage resistor. To prevent errors it is important to ensure one resistor does not change its value in relation to the other.
When calculating resistance values it is often assumed that the same current flows through both resistors. However, it is important to remember the input current to the voltage regulator or amplifier. This will flow through one resistor more than the other and cause an error.
The solution is to set the current through the divider resistors many times (typically 1000x) higher than the input current to the device. This approach tends to result in higher power losses so a trade-off is required.
Choosing the correct high voltage resistor for a particular application can be complex. The restricted standard range of resistor values, power ratings and package styles can further complicate the situation. Sometimes the only solution can be to use a custom high voltage resistor designed and manufactured, like Microhm Electronics, by a specialist supplier.
Microhm Electronics Ltd. Copyright © 2017
All Rights Reserved
