![]() R pull-up = (V supply – V H(min)) / I sinkĬalculating actual values for pull-down resistorsįor pull-down resistors, there’s a slight change to the formula, though it’s still based on Ohms law.While the current refers to the maximum current sunk by the logic pins.įormula for calculating actual value for pull-up resistors: Similarly to how we calculate resistance for a normal resistor, we’ll use the formula in Ohms law, where R = Voltage/Current or in short, R = V/I Calculating actual values for pull-up resistorsįor pull up resistors, voltage refers to the source voltage minus minimum voltage accepted as high. With many pull-up or pull-down resistors in digital logic level circuits ranging from 2 to 4.7k, we’ll need to calculate the actual values of these resistors. How to calculate values for Pull-up and Pull-down Resistors Though being less commonly used, a pull-down resistor is still a valid option. ![]() ![]() However, instead of pulling a pin to a high value, such resistors pull the pin to a low valued instead. Similarly to pull-up resistors, pull-down resistors ensure the voltage between VCC and a microcontroller pin is actively controlled when the switch is open.
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