Device configuration

UM1685

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DocID025458 Rev 2

3

Device configuration

This section offers an overview of the basic configuration steps which are required for make

the demonstration board operative. More details about the configuration of the gate driving

circuitry and the control algorithms are available in the AN4354 “L648x devices: gate drivers

setup”.

Warning:

Important - the device configuration is mandatory. The

default configuration is not operative.

Important - before changing the device configuration verify

that the device is in high impedance status (power stage is

disabled).

3.1

Voltage mode driving (EVAL6480H)

The configuration parameters of the voltage mode driving can be obtained through the

BEMF compensation tool embedded in the SPINFamily software.

A wrong setup of these parameters could cause several issues, in particular:



The phase current decreases with the speed and the motor will stall.



The wrong voltage is applied to the motor and the system is very noisy.



The phase current reaches the overcurrent limit.

The BEMF compensation form uses the application parameters as inputs in order to

evaluate the proper device setup.

The required inputs are:



Supply voltage.



Target phase current (r.m.s. value) at different motion conditions (acceleration,

deceleration, constant speed and holding).



Target operating speed (maximum speed).



Motor characteristics.

The motor characteristics are: electrical constant (Ke), phase inductance and resistance.

The inductance and the resistance of the phase are given in the motor datasheet. The Ke is

rarely given in the specification and must be measured.

In the help section of the SPINFamily software a step by step procedure is explained. The

same procedure can also be found in the application note “AN4144: Voltage mode control

operation and parameter optimization” on www.st.com.

Click on the “evaluate” button to get the suggested setup for the voltage mode driving. Then

click on “write” button to copy the data into the registers of the L6480 device.