Adc Electrical Characteristics Over Recommended Operating Conditions; Dc Specifications - Texas Instruments TMS320C2810 Data Manual

TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
SPRS174T – APRIL 2001 – REVISED MAY 2012

6.30.2 ADC Electrical Characteristics Over Recommended Operating Conditions

Resolution
(2)
ADC clock
(3)
INL (Integral nonlinearity)
(3)
DNL (Differential nonlinearity)
(4)
Offset error
Overall gain error with internal reference
Overall gain error with external reference
Channel-to-channel offset variation
Channel-to-channel Gain variation
Analog input voltage (ADCINx to ADCLO)
ADCLO
Input capacitance
Input leakage current
Accuracy, ADCV
REFP
Accuracy, ADCV
REFM
Voltage difference, ADCREFP – ADCREFM
Temperature coefficient
Reference noise
Accuracy, ADCV
REFP
Accuracy, ADCV
REFM
Input voltage difference, ADCREFP – ADCREFM
(1) Tested at 12.5-MHz ADCCLK.
(2) If SYSCLKOUT ≤ 25 MHz, ADC clock ≤ SYSCLKOUT/2.
(3) The INL degrades for frequencies beyond 18.75 MHz–25 MHz. Applications that require these sampling rates should use a 20K resistor
as bias resistor on the ADCRESEXT pin. This improves overall linearity and typical current drawn by the ADC will be a few mA more
than 24.9-kΩ bias. The ADC module in C281x devices can operate at 24.9k bias on ADCRESEXT pin for the full range 1–25 MHz.
(4) 1 LSB has the weighted value of 3.0/4096 = 0.732 mV.
(5) A single internal band gap reference (±5% accuracy) 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 the F2810, F2811, and F2812 ADC Calibration Application Report (literature number SPRA989)
and Section 5.2, Documentation Support, for relevant documents.
(6) In this mode, the accuracy of external reference is critical for overall gain. The voltage difference (ADCREFP – ADCREFM) will
determine the overall accuracy.
(7) Voltages above V + 0.3 V or below V
DDA
To avoid this, the analog inputs should be kept within these limits.
144 Electrical Specifications
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Table 6-44. DC Specifications
PARAMETER
ACCURACY
1–18.75 MHz ADC clock
1–18.75 MHz ADC clock
F281x
(5)
C281x
(6)
If ADCREFP – ADCREFM = 1 V ± 0.1%
ANALOG INPUT
(7)
INTERNAL VOLTAGE REFERENCE
EXTERNAL VOLTAGE REFERENCE
– 0.3 V applied to an analog input pin may temporarily affect the conversion of another pin.
SS
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TMS320F2810 TMS320F2811 TMS320F2812 TMS320C2810 TMS320C2811 TMS320C2812
(1)
MIN TYP
12
1
–80
–200
–80
–50
±8
±8
0
–5 0
10
3
(5)
1.9 2
0.95 1
1
50
100
(6)
1.9 2
0.95 1
0.99 1
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MAX UNIT
Bits
kHz
25 MHz
±1.5 LSB
±1 LSB
80 LSB
200
LSB
80
50 LSB
LSB
LSB
3 V
5 mV
pF
±5 µA
2.1 V
1.05 V
V
PPM/°C
µV
2.1 V
1.05 V
1.01 V