5.24 12-Bit ADC, External Reference
over recommended operating supply voltage and free-air temperature (unless otherwise noted)(1)
PARAMETER |
TEST CONDITIONS |
VCC
|
MIN |
MAX |
UNIT |
VVeREF+
|
Positive external reference input voltage |
VVeREF+> VVREF-/VeREF-(2)
|
|
1.4 |
VAVCC
|
V |
VVREF-/VeREF-
|
Negative external reference input voltage |
VVeREF+> VVREF-/VeREF-(3)
|
|
0 |
1.2 |
V |
VVeREF+ − VVREF-/VeREF-
|
Differential external reference input voltage |
VVeREF+> VVREF-/VeREF-(4)
|
|
1.4 |
VAVCC
|
V |
IVeREF+
|
Static input current, VeREF+ |
0 V ≤ VVeREF+ ≤ VAVCC
|
2.2 V, 3 V |
|
±1 |
µA |
IVREF-/VeREF-
|
Static input current, VeREF− |
0 V ≤ VVeREF− ≤ VAVCC
|
2.2 V, 3 V |
|
±1 |
µA |
(1) The external reference is used during conversion to charge and discharge the capacitance array. The input capacitance, CI, is also the dynamic load for an external reference during conversion. The dynamic impedance of the reference supply should follow the recommendations on analog-source impedance to allow the charge to settle for 12-bit accuracy.
(2) The accuracy requirements limit the minimum positive external reference voltage. Lower reference voltage levels may be applied with reduced accuracy requirements
(3) The accuracy requirements limit the maximum negative external reference voltage. Higher reference voltage levels may be applied with reduced accuracy requirements.
(4) The accuracy requirements limit the minimum external differential reference voltage. Lower differential reference voltage levels may be applied with reduced accuracy requirements.