SM320F2808-EP Datasheet, PDF (107/118 Pages) Texas Instruments – Digital Signal Processors

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6.9.7 On-Chip Analog-to-Digital Converter
SM320F2808-EP, SM320F2806-EP
SM320F2801-EP
Digital Signal Processors
SGLS316A – MARCH 2006 – REVISED FEBRUARY 2007
Table 6-36. ADC Electrical Characteristics (over recommended operating conditions)⁽¹⁾⁽²⁾
PARAMETER
MIN TYP MAX UNIT
DC SPECIFICATIONS
Resolution
12
Bits
ADC clock
1
kHz
12.5 MHz
ACCURACY
INL (Integral nonlinearity)
DNL (Differential nonlinearity)⁽³⁾
Offset error ⁽⁴⁾
Offset error with hardware trimming
Overall gain error with internal reference ⁽⁵⁾
1-12.5 MHz ADC clock (6.25 MSPS)
1-12.5 MHz ADC clock (6.25 MSPS)
-60
-60
±1.5 LSB
±1 LSB
+60 LSB
±4
LSB
+60 LSB
Overall gain error with external reference
Channel-to-channel offset variation
Channel-to-channel gain variation
ANALOG INPUT
Analog input voltage (ADCINx to ADCLO) ⁽⁶⁾
-60
+60 LSB
±4
LSB
±4
LSB
0
3
V
ADCLO
-5
0
5 mV
Input capacitance
Input leakage current
INTERNAL VOLTAGE REFERENCE ⁽⁵⁾
10
pF
±5
µA
V_ADCREFP - ADCREFP output voltage at the pin based on
internal reference
1.275
V
V_ADCREFM - ADCREFM output voltage at the pin based on
internal reference
0.525
V
Voltage difference, ADCREFP - ADCREFM
Temperature coefficient
EXTERNAL VOLTAGE REFERENCE⁽⁵⁾⁽⁷⁾
0.75
V
50
PPM/°C
V_ADCREFIN - External reference voltage input on ADCREFIN
pin 0.2% or better accurate reference recommended
ADCREFSEL[15:14] = 11b
ADCREFSEL[15:14] = 10b
ADCREFSEL[15:14] = 01b
1.024
V
1.500
V
2.048
V
AC SPECIFICATIONS
SINAD (100 kHz) Signal-to-noise ratio + distortion
67.5
dB
SNR (100 kHz) Signal-to-noise ratio
68
dB
THD (100 kHz) Total harmonic distortion
-79
dB
ENOB (100 kHz) Effective number of bits
10.9
Bits
SFDR (100 kHz) Spurious free dynamic range
83
dB
(1) Tested at 12.5 MHz ADCCLK.
(2) All voltages listed in this table are with respect to V_SSA2.
(3) Texas Instruments specifies that the ADC will have no missing codes.
(4) 1 LSB has the weighted value of 3.0/4096 = 0.732 mV.
(5) A single internal/external 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 listed for the internal reference
is inclusive of the movement of the internal bandgap over temperature. Gain error over temperature for the external reference option will
depend on the temperature profile of the source used.
(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.
(7) Texas Instruments recommends using high precision external reference Texas Instruments part REF3020/3120 or equivalent for
2.048-V reference.
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Electrical Specifications 107