Datasheet

TMC4671 Datasheet • IC Version V1.3 | Document Revision V2.00 • 2020-Apr-17

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3.5.4 IgainADC[A/LSB] - ADC Integer Current Value to Real World Unit

Together with ADC_I0_SCALE and ADC_I0_OFFSET and ADC_I1_SCALE and ADC_I1_OFFSET, measured ADC

currents represented as 16 bit signed interger numbers (s16) represent real world currents. Multiplication

of integer current value with gain scaling factor in unit Ampere per LSB (Low Signiﬁcant Bit) gives the real

world value of current in unit Ampere.

[A] = IgainADC[A/LSB] ∗ ADC_I0

[A] = IgainADC[A/LSB] ∗ ADC_I1

(3)

Diﬀerent scalings between two associated current ADC channels can be trimmed by programing ADC_I0_SCALE

and ADC_I1_SCALE. The IgainADC[A/LSB] needs to be determined from ADC gain factors, ADC reference

voltage selection, and actual ADC scaling factor settings.

3.5.5 UgainADC[V/LSB] - ADC Integer Voltage Value to Real World Unit

Measured ADC voltages represented as 16 bit signed interger numbers (s16) represent real world voltages.

Multiplication of integer voltage value with gain scaling factor in unit Volt per LSB (Low Signiﬁcant Bit) gives

the real world value of voltage in unit Volt.

U[V ] = UgainADC[V/LSB] ∗ ADC_U

(4)

The UgainADC[V/LSB] needs to be determined from ADC gain factors, actual ADC gains, and ADC reference

voltage settings.

3.5.6 Measurement of Rotor Angle

Determination of the rotor angle is either done by sensors (digital encoder, analog encoder, digital Hall

sensors, analog Hall sensors) or sensorless by a reconstruction of the rotor angle. Currently, there are no

sensorless methods available for FOC that work in a general purpose way as a sensor down to velocity

zero.

The TMC4671 does not support sensorless FOC.

3.5.7 Measured Rotor Angle vs. Magnetic Axis of Rotor vs. Magnetic Axis of Stator

The rotor angle, measured by an encoder, needs to be adjusted to the magnetic axis of the rotor. This is

because an incremental encoder has an arbitrary orientation relative to the magnetic axis of the rotor, and

the rotor has an arbitrary orientation to magnetic axis of the stator.

The direction of counting depends on the encoder, its mounting, and wiring and polarities of encoder

signals and motor type. So, the direction of encoder counting is programmable for comfortable deﬁnition

for a given combination of motor and encoder.

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