VPP655 PWM Input: direct 3.3v interface possible?

[daxjupp]

Hi Folks,

I'm hoping to control a VPP655 with a 25kHz PWM signal generated from a 3.3v microcontroller (which is not 5v tolerant), so I would like to know if the pump uses an internal pull-up resistor to 5v before I release any magic smoke. If it doesn't utilise a pull-up, would it accept a 3.3v directly from a microcontroller and still provide the entire 0-100% range?

Many thanks for any advice you kind folks can offer with this.

All the best,

Dax

 

[Vanzin]

HI,

I am sorry but we can´t help you with this and we won´t support this. The pump is intented to be connected directly to a 12V power supply and PWM controlled with a compatible controller like a normal motherboard.

 

[daxjupp]

HI,

I am sorry but we can´t help you with this and we won´t support this. The pump is intented to be connected directly to a 12V power supply and PWM controlled with a compatible controller like a normal motherboard.

Thank you for getting back to me.

I have read the recommended specifications for PWM fans as documented by Intel (here) and note, on page 9, they state (emphasis mine):

New fan designs are strongly encouraged to implement a 3.3v pull up for compatibility with buffer design limits on Hardware Monitor Devices e.g. Super IO devices.

However, I have noticed some old PWM fans pull up to 5v. Therefore, I will assume your pumps conform to the Intel fan recommendations in all other regards, and I will incorporate level shifting to 5v for the PWM to be safe.