POWERSTEP01 datasheet(41/92 Pages) STMICROELECTRONICS

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DocID025022 Rev 5

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powerSTEP01

Phase current control: voltage mode

To obtain different current values during acceleration and deceleration phase, two different

final slope values, and consequently two different compensation curves, can be

programmed.

Acceleration compensation curve is applied when the motor runs. No BEMF compensation

is applied when the motor is stopped.

8.5

Motor supply voltage compensation

The sinewave amplitude generated by the PWM modulators is directly proportional to the

motor supply voltage (VS). When the motor supply voltage is different from its nominal

value, the motor phases are driven with an incorrect voltage. The powerSTEP01 can

compensate motor supply voltage variations in order to avoid this effect.

The motor supply voltage should be connected to the integrated ADC input through

a resistor divider in order to obtain VREG/2 voltage at the ADCIN pin when VS is at its

nominal value (see Figure 18).

The ADC input is sampled at fS frequency, which is equal to PWM frequency.

Figure 17. BEMF compensation curve

AM12835v1

Speed

Compensation

value

INT_SPEED

ST_SLP

FN_SLP_ACC

FN_SLP_DEC

Figure 18. Motor supply voltage compensation circuit

AM12836v1

ADCIN

ADC

PWM

ADC_OUT

REG

ADCIN = VS x RB

/ (R

+ R

)

POWERSTEP01 Datasheet(PDF) 41 Page - STMicroelectronics