Problems with Easydriver current

[mvoltin]

I am having terrible problems with high currents and Easydriver and already fried two of them (with sparks and smoke coming out of the main IC and the chip getting a huge bump from the "explosion"). both are related to excessive current requirements but I thought EasyDriver limited the max current to 750mA irrespective of motor demands or PSU supply. Does it need any current restrictor and why (since other drivers do not need this)? If it does, any suggestion would be appreciated.

In both cases, I used 24V 1.6A PSU and motor was either 5 or 24V with around 1.2 amp per winding. They both worked fine without a load but, under a load (as it drew more current - I assume) the Easydriver blew up.

P.S. I am planning on getting another set of drivers but wanted to understand what is happening or what I am doing wrong since I plan to use Easydrivers for other projects. I have read some people restricting the current to the driver but cannot understand why this would be needed.

 

[mrinalmani]

Well I dont see a short-circuit current limit of 750mA anywhere in the datasheet.

 

[mvoltin]

Do you suspect there was a short-circuit somewhere or is this a specific type of current limiting? Sorry, I am new to the field. It happened on two separate drivers with different motors in each case. In both cases, the motors worked fine until I put load on them and then the ED blew up within 1 second. Both motors were rated around 1.2 or 1.5 amps. So, I was thinking it was because of excessive current draw.

The datasheet states: "The current in each of the two output H-bridges is regulated with fixed off time pulsewidth modulated (PWM) control circuitry. The H-bridge current at each step is set by the value of an external current sense resistor (RS), a reference voltage (VREF), and the DAC’s output voltage controlled by the output of the translator." and "Adjustable current control from 150mA/phase to 750mA/phase"

So, it should not have let more than 750mA through but it burned when the current demand increased.