TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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Hexadecimal Value
0x5555h
u16
21845
27306
s16 PHI[°] ±PHI[°]
21845 120.0
-240.0
-210.0
-180.0
-150.0
-120.0
-90.0
0x6AAAh
27768 150.0
0x8000h
32768 -32768 180.0
38229 -27307 210.0
43690 -21846 240.0
49152 -16384 270.0
54613 -10923 300.0
0x9555h
0xAAAAh
0xC000h
0xD555h
-60.0
0xEAAAh
60074
-5462 330.0
-30.0
Table 6: Examples of u16, s16, q8.8
The option of adding an offset is for adjustment of angle shift between the motor and stator and the rotor
and encoder. Finally, the relative orientations between the motor and stator and the rotor and encoder can
be adjusted by just one offset. Alternatively, one can set the counter position of an incremental encoder to
zero on initial position. For absolute encoders, one needs to use the offset to set an initial position.
4.4 ADC Engine
The ADC engine controls the sampling of different available ADC channels. The ADC channels (ADC_I0_POS,
ADC_I0_NEG, ADC_I1_POS, ADC_I1_NEG) for current measurement are differential inputs. For analog
Hall and for analog encoder, the ADC channels have differential inputs (AENC_UX_POS, AENC_UX_NEG,
AENC_VN_POS, AENC_VN_NEG, AENC_WY_POS, AENC_WY_NEG). Two general purpose ADC channels
are single-ended analog inputs (AGPI_A, AGPI_B). The ADC channel for measurement of supply voltage
(ADC_VM) is associated with the brake chopper.
The FOC engine expects offset corrected ADC values, scaled into the FOC engine’s 16 bit (s16) fixed
point representation. The integrated scaler and offset compensator maps raw ADC samples of current
measurement channels to 16 bit two’s complement values (s16). While the offset is compensated by
subtraction, the offset is represented as an unsigned value. The scaling value is signed to compensate
wrong measurement direction. The s16 scaled ADC values are available for read out from the register by
the user.
Wrong scaling factors (ADC_SCALE) or wrong offsets (ADC_OFFSET) might cause
damages when the FOC is active. Integrated hardware limiters allow protection -
especially in the setup phase when using careful limits.
Info
ADC samples for measurement of supply voltage (VM) and the general purpose analog ADC inputs are
available as raw values only without digital scaling. This is because these values are not processed by the
FOC engine. They are just additional ADC channels for the user. The general purpose analog inputs (AGPI)
are intended to monitor analog voltage signals representing MOSFET temperature or motor temperature.
AGPI_A can also be used for the Single Pin Interface (please see section 4.8.10).
ADC_VM must be scaled down by voltage divider to the allowed voltage range,
and might require additional supply voltage spike protection.
Info
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