SM320F2812-HT Datasheet, PDF (135/155 Pages) Texas Instruments – Digital Signal Processor

SM320F2812-HT
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SGUS062A – JUNE 2009 – REVISED APRIL 2010
6.29.2 ADC Electrical Characteristics Over Recommended Operating Conditions
Table 6-46. DC Specifications^{(1) (2)}
PARAMETER
T_A = –55°C to 220°C
MIN
TYP
MAX
UNIT
Resolution
ADC clock⁽³⁾
12
Bits
1
kHz
25
MHz
INL (Integral nonlinearity)⁽⁴⁾
DNL (Differential nonlinearity)⁽⁴⁾
Offset error⁽⁵⁾
ACCURACY
1–18.75 MHz ADC clock
1–18.75 MHz ADC clock
±1.5
LSB
±1
LSB
–80
80
LSB
Overall gain error with internal
reference ⁽⁶⁾
–200
200
LSB
Overall gain error with external
reference ⁽⁷⁾
If ADCREFP-ADCREFM = 1 V ±0.1%
–50
50
LSB
Channel-to-channel offset variation
±8
LSB
Channel-to-channel Gain variation
±8
LSB
ANALOG INPUT
Analog input voltage (ADCINx to
ADCLO) ⁽⁸⁾
0
3
V
ADCLO
–5
0
5
mV
Input capacitance
10
pF
Input leakage current
INTERNAL VOLTAGE REFERENCE⁽⁶⁾
3
±5
mA
Accuracy, ADCV_REFP
Accuracy, ADCV_REFM
Voltage difference, ADCREFP –
ADCREFM
1.9
2
2.1
V
0.95
1
1.05
V
1
V
Temperature coefficient
50
PPM/°C
Reference noise
100
V
EXTERNAL VOLTAGE REFERENCE⁽⁷⁾
Accuracy, ADCV_REFP
Accuracy, ADCV_REFM
Input voltage difference, ADCREFP –
ADCREFM
1.9
2
2.1
V
0.95
1
1.05
V
0.99
1
1.01
V
(1) Not production tested.
(2) Tested at 12.5-MHz ADCCLK
(3) If SYSCLKOUT ≤ 25 MHz, ADC clock ≤ SYSCLKOUT/2
(4) The INL degrades for frequencies beyond 18.75 MHz –25 MHz. Applications that require these sampling rates should use a 20-kΩ
resistor as bias resistor on the ADCRESEXT pin. This improves overall linearity and typical current drawn by the ADC is a few mA more
than 24.9 kW bias.
(5) 1 LSB has the weighted value of 3.0/4096 = 0.732 mV.
(6) 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 is 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.
(7) In this mode, the accuracy of external reference is critical for overall gain. The voltage difference (ADCREFP–ADCREFM) determines
the overall accuracy.
(8) 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.
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Electrical Specifications 135