DRV8434A-Q1: DRV8434 Motor Driver Design Problems

Hello Wang,

wang sky said:

1. Can the TRQ_CNT/STL_TH PIN of the DRV8434 be connected to the GPIO of the MCU without the need to connect to the GPIO of the MCU?

    Is it possible to use a voltage value for this PIN as an action point for Torque count and stall threshold?

If I understood correctly your question was "can this pin be used as analog voltage input for stall threshold for example by using a voltage divider resistor network, correct?". This pin function is determined by the STL_MODE pin. While STL_MODE = 0, the TRQ_CNT/STL_TH pin is an analog voltage output pin. The analog voltage value represents the torque count while the stepper is running normally in an application with a steady state speed. This can be read by an ADC input of the MCU. While STL_MODE = 1 this pin will be an analog voltage input and the voltage input would be the stall threshold voltage that would be internally compared with the torque count to determine whether the stepper is stalled or not. This voltage can be generated using a DAC by the MCU or can be manually set with either two resistors or a 50 kΩ trimpot.

While STL_MODE is HiZ (unconnected) the device will work in stall learn mode. After a learn procedure the threshold voltage will be internally recorded and will be used for comparison with torque count and determine a stall or no stall. With this mode after every power cycle or nSLEEP cycle a learning procedure must be done. 

wang sky said:

2.When nFAULT is changed from H to L or STR_REP is changed from L to H, how to change these two error signals back to the normal level after they are generated?

These two faults can be cleared using a nSLEEP reset pulse. See below. The reset pulse must be between 20 and 40 μs, for example 30 μs. This pulse would clear just the pulse and not affect any other logic including the indexer table position and the learnt value of the stall threshold. If the nSLEEP reset pulse goes longer than 120 μs the device will enter sleep state where all faults will be cleared as well as the indexer will reset to home position and the learnt value of stall threshold will be erased so it must be relearnt if the device is configured for stall learning mode operation. 

wang sky said:

Is it possible to clear the error signal by using the ENABLE pin?

ENABLE pin function is only to disable the H-bridge outputs. It does not clear any faults.

wang sky said:

3.When the nSLEEP of DRV8434 changes from H to L and the device enters SLEEP MODE, will the stator of the stepper motor still be excited?

During the sleep state the output bridges will be disabled and the stepper motor will not be excited - no current flow.

Thank you.

Regards, Murugavel 

Thank you for your help and assistance.