Electrical Specifications
128
June 2004
SPRS257
6.29.2
ADC Electrical Characteristics Over Recommended Operating Conditions
Table 6
38. DC Specifications (See Note 1)
PARAMETER
Resolution
MIN
TYP
MAX
UNIT
Bits
kHz
MHz
12
1
ADC clock (See Note 2)
25
ACCURACY
INL (Integral nonlinearity)
DNL (Differential nonlinearity)
Offset error (See Note 3)
Overall gain error with internal reference
(See Note 4)
Overall gain error with external reference
(See Note 5)
Channel-to-channel offset variation
Channel-to-channel Gain variation
±
1.5
±
1
LSB
LSB
LSB
±
80
±
50
LSB
If ADCREFP-ADCREFM = 1 V
±
0.1%
±
50
LSB
±
8
±
8
LSB
LSB
ANALOG INPUT
Analog input voltage (ADCINx to ADCLO)
(See Note 6)
ADCLO
Input capacitance
Input leakage current
0
3
V
5
0
5
mV
pF
μ
A
10
3
±
5
INTERNAL VOLTAGE REFERENCE
(See Note 4)
Accuracy, ADCV
REFP
Accuracy, ADCV
REFM
Voltage difference, ADCREFP - ADCREFM
Temperature coefficient
Reference noise
2
1
1
V
V
V
50
100
PPM/
°
C
μ
V
EXTERNAL VOLTAGE REFERENCE (See Note 5)
Accuracy, ADCV
REFP
Accuracy, ADCV
REFM
Input voltage difference,
ADCREFP - ADCREFM
1.9
0.95
2
1
2.1
1.05
V
V
0.99
1
1.01
V
NOTES:
1. Tested at 12.5-MHz ADCCLK
2. If SYSCLKOUT
≤
25 MHz, ADC clock
≤
SYSCLKOUT/2
3. 1 LSB has the weighted value of 3.0/4096 = 0.732 mV.
4. A single tirmmed internal band gap reference sources both ADCREFP and ADCREFM signals, and hence, these voltages track
together. The ADC converter uses the difference between these two as its reference. The total gain error will be the combination
of the gain error shown here and the voltage reference accuracy (ADCREFP - ADCREFM). A software-based calibration
procedure is recommended for better accuracy. See
F2812 ADC Calibration Application Note
(literature number SPRA989) and
Section 5.2, Documentation Support, for relevant documents.
5. In this mode, the accuracy of external reference is critical for overall gain. The voltage difference (ADCREFP-ADCREFM) will
determine the overall accuracy.
6. Voltages above V
DDA
+ 0.3 V or below V
SS
- 0.3 V applied to an analog input pin may temporarily affect the conversion of another
pin. To avoid this, the analog inputs should be kept within these limits.
A