TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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Figure 16: ADC Selector & Scaler w/ Offset Correction
ADC offsets and ADC scalers for the analog current measurement input channels need to be programmed
into the associated registers. Each ADC_I_U, ADC_I_V, ADC_I_UX, ADC_I_WY, ADCSD_I_UX, ADCSD_I_WY,
ADC_I0_EXT, and ADC_I1_EXT is mapped either to ADC_I0_RAW or to ADC_I1_RAW by ADC_I0_SELECT and
ADC_I1_SELECT.
In addition, the ADC_OFFSET is for conversion of unsigned ADC values into signed ADC values as required
for the FOC.
ADC_I0 = (ADC_I0_RAW − ADC_I0_OFFSET) · ADC_I0_SCALE
ADC_I1 = (ADC_I1_RAW − ADC_I1_OFFSET) · ADC_I1_SCALE
(17)
(18)
For FOC3, the third current ADC_I2 is calculated via Kirchhoff’s Law. This requires the correct scaling and
offset correction beforehand. For FOC2, there is no calculation of a third current.
The ADC_UX_SELECT selects one of the three ADC channels ADC_I0 ADC_I1, or ADC_I2 for ADC_UX.
The ADC_V_SELECT selects one of the three ADC channels ADC_I0 ADC_I1, or ADC_I2 for ADC_V.
The ADC_WY_SELECT selects one of the three ADC channels ADC_I0 ADC_I1, or ADC_I2 for ADC_WY.
The ADC_UX, ADC_V, and ADC_WY are for the FOC3 (U, V, W). The ADC_UX and ADC_WY (X, Y) are for the
FOC2.
Note
The open-loop encoder is useful to run a motor open loop for setting up the ADC
channel selection with correct association between phase currents I_U, I_V, I_W
and phase voltages U_U, U_V, U_W.
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