TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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= 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)
5.0
(0.0)
(0.0)
(0.825)
1.250
(1.65)
2.50
(2.75)
3.75
(3.3)
(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_MAX
for
V_IN
(V_IN − V_REF)
V_IN
>
<
<
V_MAX
V_MAX
V_MIN
V_RAW
=
(9)
(V_IN − V_REF) for V_MIN
<
V_MIN
for
The resulting raw ADC value is
V_RAW
V_MAX
16
ADC_RAW = (2 − 1) ·
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
0x0000 . . . 0xFFFF.
{
0
. . . (216)
−
1
} <
=
> {0 . . . 65535} <
=>
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 12: Delta Sigma input voltage mapping of internal Delta Sigma Modulators
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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