I recently had to move from a 5v Arduino to a 3.3V Arduino that is not 5V tolerant. My design includes a TB9051FTG Single Brushed DC Motor Driver Carrier and I am trying to determine if it can still be used.
My initial thought was to use a bidirectional level converter for the purely digital interface connections. The OCM output is analog and there is at least some risk that it could exceed 3.3v and damage the Arduino.
Has anyone driven the TB9051FTG Single Brushed DC Motor Driver Carrier from a 3.3v controller?
Can I just ignore the OCM output and not connect it?
If so, will the Arduino library still work?
Are there any other catastrophic issues or repercussions?
Bob Segrest
The minimum operating voltage for VCC on the TB9051FTG driver is listed as 4.5V, so you should power it from 5V. However, all of the inputs should work fine with 3.3V signals. The output pins are not strictly necessary to use the driver, but we do not provide a library for our TB9051FTG Single Brushed DC Motor Driver Carrier; what library are you using?
The OCM output should be okay since it outputs 500mV/A, so it won’t exceed 3.3V until the current is over 6A, which is beyond what the driver is rated for.
The DIAG pin on our TB9051FTG Single Brushed DC Motor Driver Carrier is pulled up to VCC, so it might be a good idea to use a level shifter if you need that fault output. However, the pull-up is relatively weak (10kΩ) and there’s an additional 220Ω inline resistor so you might be able to get away with connecting it to a 3.3V input pin directly.
By the way, if you are using an Arduino with the standard Uno form factor, you might consider using the Dual TB9051FTG Motor Driver Shield for Arduino, which would simplify the connections and pull DIAG up to a separate IOREF voltage instead, making it easier to use with a 3.3V Arduino.
Brandon
Thank you Brandon, that is what I was looking for.
My original controller was an Uno, but I ended up rolling over to a Teensy 4.1 board. Thus the need for the 3.3v interface.
Bob
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