Request for DRV 8825 circuit diagram

Hi Raja,

Can you provide more information?
    Does the motor move or make any sound when attempting to move?
    How much current does the board use before and after the device is enabled (nENBL is low)?
    Does the nFAULT pin go low?
    What is the votage on AVREF/BVREF?
    What is the voltage on nENBL, nRESET, and nSLEEP when trying to run the motor?
    What is the initial STEP rate (frequency of STEP pin)?
    What step mode is being used?
    What voltage is VMM?

If the motor attempts move or produces sound, this is an indication that the motor driver has been enabled and is providing current to the motor.  Further movement could be restricted by nFAULT asserting due to a drop in VMM or by the initial speed commanded of the motor being too fast. If nFAULT is asserting, try increasing the capacitance on VMM. If nFAULT is not being asserted, it could be due to the step rate being faster than the motor can start. Try reducing the starting speed of the motor, and slowing increase the speed to the target speed.

If the motor does not attempt to move, it could be due to incorrect control signals. nSLEEP and nRESET should be at a logic high, and nENBL should be at a logic low. AVREF/BVREF should be set to a value to create the chopping current.

If the motor still does not move, please send the information requested above. Scope shots also can help, particularly the current.

Hi

           Thank you for immediate reply, here am mention the details what you , motor is not rotate, their is no any initial rotation 

I also have the another issue on regulator IC , LMZ23610 , Here am regulate the output volt as 3.9V , and am drive the Power LED , with a *** of 3.9V/9A ,  But it drive up to 3A , if am increase the current it getting heat .... pls can u provide any circuit for that...

Hi Raja,

First, please lower VREF to .8V. This will reduce the possibility of thermal issues, but still provide 1.1A in the windings. If the motor begins spinning, please limit VREF to 1.7V or less (see the motor spec) in full step mode.

This will keep the current below 2.5A per winding based on the information you provided. Please keep in mind  this current is a maximum and may be affected by the layout.

If the motor does not spin, please answer a few more questions.

After nENBL is 0V, nRESET is 4.4V and nSLEEP is 4.7, what is the current used in the VMM path? At this point the DRV8825 outputs should be enabled and driving current through the motor. If you only see a few mA, there may be a connection problem at the inputs or the outputs.

Do you have a second board to try? It may provide insight.

Are you measuring nFAULT and VMM with a multimeter or scope?  If a multimeter, you will only see the average voltage, not any dips that could cause problems. Please use a scope and provide scope shots when trying to spin the motor.

If you have a current probe, scope shots of the motor currents are particularly helpful.

What is the frequency of STEP when you are trying to move the motor? Do you go through an acceleration profile to achieve the target speed?

I suggest you post the question on the LMZ23610 on the Power Management, Simple Switcher forum. The experts for this device reside there.