Can the MAX6641 be used with a fan powered higher than 12V?

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Accepted Answer

There shouldn't be an issue if the following conditions are satisfied. 1. The PWMOUT is used to drive the gate of low-side transistor as shown below. 2. The MOSFET can sink the current flowing through the fan without getting damaged. 3. The MOSFET has small enough on resistance, and threshold voltage (V_GS) such that it will turn on when the gate source voltage is at 5V. Please note that the PWM invert bit (D4 in register 02h) needs to be set to 1 so that PWMOUT is forced high when the duty cycle is 100%. However, there would be an issue if it is used as high-side as shown below. The absolute maximum ratings would be violated.

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MAX6641: FAQ