TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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Vmin[V] Vref[V] Vmax[V] VIN[V] DUTY[%] ADC_RAW
0.0
0.0
0.0
0.0
0.0
1.65
1.65
1.65
1.65
1.65
3.3
3.3
3.3
3.3
3.3
0.0
0.825
1.65
2.475
3.3
0%
25%
0x0000
0x4000
0x7fff
50%
75%
0xC000
0xffff
100%
Vmin[V] Vref[V] Vmax[V] VIN[V] DUTY[%] ADC_RAW
0.0
0.0
0.0
0.0
0.0
2.5
2.5
2.5
2.5
2.5
5.0
5.0
5.0
5.0
5.0
0.0
1.0
0%
25%
0x0000
0x4000
0x7fff
2.5
50%
3.75
5.0
75%
0xC000
0xffff
100%
Table 14: Delta Sigma input voltage mapping of external comparator (CMP)
4.6 Analog Signal Conditioning
The range of measured coil currents, resp. the measured voltages of sense resistors, needs to be mapped
to the valid input voltage range of the delta sigma ADC inputs. This analog preprocessing is the task of the
analog signal conditioning.
4.6.0.1 Chain of Gains for ADC Raw Values
An ADC raw value is a result of a chain of gains that determine it. A coil current I_SENSE flowing through a
sense resistor causes a voltage difference according to Ohm’s law. Finally, a current is mapped to an ADC
raw value
ADC_RAW = (I_SENSE ∗ ADC_GAIN) + ADC_OFFSET.
(11)
The ADC_GAIN is a result of a chain of gains with individual signs. The sign of the ADC_GAIN is positive
or negative, depending on the association of connections between sense amplifier inputs and the sense
resistor terminals. The ADC_OFFSET is the result of electrical offsets of the phase current measurement
signal path. For the TMC4671, the maximum ADC_RAW value is ADC_RAW_MAX = (216
ADC raw value is ADC_RAW_MIN = 0.
−
1) and the minimum
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