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UCD90910: UCD90910 Fan control IO pins

Part Number: UCD90910

Hi 

Your technical department has confirmed the Fan drive 'FPWM' outputs are limited to 3v3 due to the internal protection diodes.

Just to mention - the data sheet is a bit misleading as it shows a direct PWM fan drive from the IC to the 12V fan PWM input.

I now have to add 2 transistors to the output drive of each of the 10 fans.

Two transistors are needed to ensure the signal is not inverted. 

Instead of the transistor PWM drive can I use a series resistor to reduce the voltage back into the IC.

I have included an image of the Fan PWM input and  the transistor drive circuit I have initially used.