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Electronics => Electronics => Topic started by: silo_xtreme on April 01, 2010, 12:26:16 PM

Title: VNH3SP30 with 3.3V controller?
Post by: silo_xtreme on April 01, 2010, 12:26:16 PM

Hi All,

I need a sanity check here.  Is it possible to use a 3.3V Atmel chip with the VNH3SP30?

http://pdf1.alldatasheet.com/datasheet-pdf/view/84563/STMICROELECTRONICS/VNH3SP30.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/84563/STMICROELECTRONICS/VNH3SP30.html)

I'm a little confused form their 3.25V test data and the other information in the data sheet.

I'd really appreciate your help!

Mike

Title: Re: VNH3SP30 with 3.3V controller?
Post by: Razor Concepts on April 01, 2010, 12:54:17 PM

As long as the h-bridge itself is being powered by at least 5.5 volts, the 3.3v logic level high sent by the atmel chip should control it fine.

Title: Re: VNH3SP30 with 3.3V controller?
Post by: silo_xtreme on April 01, 2010, 12:58:33 PM

The INA , INB and PWM are at 5V

The Enable/Diag pins are at 3.3V

For some reason this doesn't turn on the motor.

The strange things is that when I cycle the VCC power, the motor starts to work.

Any ideas?

Title: Re: VNH3SP30 with 3.3V controller?
Post by: Soeren on April 01, 2010, 05:14:22 PM

Hi,

Quote from: silo_xtreme on April 01, 2010, 12:58:33 PM

The Enable/Diag pins are at 3.3V

For some reason this doesn't turn on the motor.

The strange things is that when I cycle the VCC power, the motor starts to work.

The 3.3V is in itself pretty close to the 3.25V. Add the hysteresis of 0.5V and it's going on one wing and a prayer.
You could use small signal transistors and pull ups, or a (6x or 8x) buffer/level translator circuit to get the voltages in check.