datasheet question for A3979

[drkidd22]

3Hello,

I'm trying to build a regulated 5V power supply for the A3979 motor control chip from Allegro.

Allegro's datasheet states Logic Supply Current of 10mA - 12mA at 5.5V. So my question is will this spec be per channel or for the entire component. I will be using the LM2940 SOT223 1A current regulator, but need to figure out what kind of thermal issues I may have. The input voltage will be at a max of 28V. I'll be ok with no heat sink if the total current draw from the A3979 is 10mA, but may need to add heat sinking or work on the board layout if the current draw is greater than 25mA.

LM2940 SOT223 Rthj-amb = 174°C/W

https://www.electro-tech-online.com/custompdfs/2011/10/3834_9917_1.pdf
https://www.electro-tech-online.com/custompdfs/2011/10/LM2940.pdf

 

[crutschow]

The A3979 data sheet states that the maximum logic supply current at up to 5.5V is 12mA for a PWM output of <50kHz. That value should be for all channels being controlled.