Datasheet

TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.03 • 2018-Sept-06
28 / 158
= 5V where V_MAX = 3.3V is possible. The table 11 defines the recommended voltage ranges for both 5V
and 3.3V analog supply voltages.
V_SUPPLY[V] (V_MIN[V]) V_MIN25%[V] V_MAX50%[V] V_MAX75%[V] (V_MAX[V])
(3.3) (0.0) (0.825) (1.65) (2.75) (3.3)
5.0 (0.0) 1.250 2.50 3.75 (5.0)
Table 11: Recommended input voltage range from V_MIN25%[V] to V_MAX75%[V] for internal Delta Sigma
Modulators; V_SUPPLY[V] = 5V is recommended for the analog part of the TMC4671.
V_RAW =









V_MAX for V_IN > V_MAX
(V_IN − V_REF) for V_MIN < (V_IN − V_REF) < V_MAX
V_MIN for V_IN < V_MIN
(9)
The resulting raw ADC value is
ADC_RAW = (2
16
− 1) ·
V_RAW
V_MAX
for V_MIN25%[V] < V_RAW < V_MAX75%[V]. (10)
The idealized expression (equation 9) is valid for recommended voltage ranges (table 11) neglecting
deviations in linearities. These deviations primarily depend on different impedance on the analog signal
path, but also on digital parameterization. Finally, the deviation is quantified in terms of resulting ADC
resolution.
So, the Delta Sigma ADC engine maps the analog input voltages V_RAW = V_IN - V_REF of voltage
range V_MIN < V_RAW < V_MAX to ADC_RAW values of range { 0 . . . (2
16
) − 1 } < = > {0 . . . 65535} < = >
0x0000 . . . 0xFFFF.
Vmin[V] Vref[V] Vmax[V] VIN[V] DUTY[%] ADC_RAW
0.0 2.5 5.0 (0.0) (0%) (0x0000)
0.0 2.5 5.0 1.0 25% 0x4000
0.0 2.5 5.0 2.5 50% 0x7fff
0.0 2.5 5.0 3.75 75% 0xC000
0.0 2.5 5.0 (5.0) (100%) (0xffff)
Table 12: Delta Sigma input voltage mapping of internal Delta Sigma Modulators)
Info
For calibrating purposes, the input voltage of the delta sigma ADC inputs can be
programmed to fixed voltages (25%, 50%, 75% of analog supply voltage) via the
associated configuration register DS_ANALOG_INPUT_STAGE_CFG.
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