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WHAT'S YOUR ENGINEERING QUOTIENT?

Problem 5—If the resolution of an encoder wheel is N stripes per revolution, what is the maximum encoding resolution when the wheel is encoded by a quadrature encoder?

ANSWER

Problem 6—Johnny built a 12 V solenoid low-side driver using a low-threshold MOSFET driven by an output pin on a microprocessor. Later, testing determined that the driver was generating unacceptable noise levels. Johnny decided to increase the switching time of the MOSFET to roughly 0.5 V/ıS by adding a resistor in series with the MOSFET gate.

Typical MOSFET specs are Ciss = 1500 pf, Crss = 90 pf, Rdson <= 0.1 ohm, Gate Threshold Voltage (Vgsth) = 1.9 V.

The microcontrollerıs output pin high voltage (Voh) is 4.5 V

How did Johnny compute the gate resistor value?

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