Hi engineers, technicians and all who know electronic better than me.
I wanted to control a step motor with arduino via A4899 drive. I didn't want USB powering so i used following wiring (just power wiring are depicted). Two socket from 12 V 3 A adaptor, one for board and one for A4899 and other elements were used. Grounds all connected together and to one side of all buttons. I should mention some buttons for controlling and a 1602 LCD for displaying were used. Please consider my powering and give me your nice notes.
If you power the Uno from 12V into the Vin or power plug, the available current from the Uno 5V regulator is very limited. The recommended max dissipation of the 5V regulator is 1 Watt. With 12V input the max current that the regulator can supply and stay under 1W is 140mA (1W / (12V - 5V) = 143mA). The Uno uses about 50mA, that leaves about 90mA for other things. The LCD backlight uses a chunk of the 90mA leaving little for the rest of the circuit. If the current is such that the 1W is exceeded the regulator will go into thermal shut down.
The solution is to use a buck converter to drop the 12V to a well regulated 5V and connect to the Uno 5V, bypassing the regulator.
groundFungus:
If you power the Uno from 12V into the Vin or power plug, the available current from the Uno 5V regulator is very limited. The recommended max dissipation of the 5V regulator is 1 Watt. With 12V input the max current that the regulator can supply and stay under 1W is 140mA (1W / (12V - 5V) = 143mA). The Uno uses about 50mA, that leaves about 90mA for other things. The LCD backlight uses a chunk of the 90mA leaving little for the rest of the circuit. If the current is such that the 1W is exceeded the regulator will go into thermal shut down.The solution is to use a buck converter to drop the 12V to a well regulated 5V and connect to the Uno 5V, bypassing the regulator.
I must think about it.
My other consumer is A4899 driver which i don't know exact consumption (VDD). Do you think a few power more than 1 watt may shout down the system?
I afraid connecting any thing to Vin, is current and voltage of buck converter fair enough? I see many models are available in our shops (most of them are Chinese) for example MP1584EN, what is your opinion? (before using A4899, I've used some other drivers which are not good, so i know that i can't buy a module just based on its properties.)
Is there any other issue to explain to me?
My i get all of my 5 v from a dc-dc reductor( buck converter)? Is it 5 v stable and precis fir them?