HI5804 Datasheet, PDF (9/11 Pages) Intersil Corporation – 12-Bit, 5 MSPS A/D Converter

HI5804
TABLE 1. A/D CODE TABLE
DIFFERENTIAL
OFFSET BINARY OUTPUT CODE
INPUT VOLTAGE† _MSB
CODE CENTER (USING INTERNAL
LSB
DESCRIPTION
REFERENCE)
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
+Full Scale
(+FS) - ¹/₄ LSB
+FS - 1¹/₄ LSB
+ ³/₄ LSB
- ¹/₄ LSB
-FS + 1³/₄ LSB
+1.99976V
1.99878V
732.4µV
-244.1µV
-1.99829V
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
1
-Full Scale (-FS)
+ ³/₄ LSB
-1.99927V
0
0
0
0
0
0
0
0
0
0
0
0
† The voltages listed above represent the ideal center of each offset binary output code.
Static Performance Definitions
Offset Error (V_OS)
The midscale code transition should occur at a level ¹/₄ LSB
above half-scale. Offset is defined as the deviation of the
actual code transition from this point.
Full-Scale Error (FSE)
The last code transition should occur for an analog input that
is ³/₄ LSB below positive full-scale with the offset error
removed. Full-scale error is defined as the deviation of the
actual code transition from this point.
Differential Linearity Error (DNL)
DNL is the worst case deviation of a code width from the
ideal value of 1 LSB.
Integral Linearity Error (INL)
INL is the worst case deviation of a code center from a best
fit straight line calculated from the measured data.
Power Supply Sensitivity
Each of the power supplies are moved plus and minus 5%
and the shift in the offset and gain error (in LSBs) is noted.
Dynamic Performance Definitions
Fast Fourier Transform (FFT) techniques are used to
evaluate the dynamic performance of the HI5804. A low
distortion sine wave is applied to the input, it is coherently
sampled, and the output is stored in RAM. The data is then
transformed into the frequency domain with an FFT and ana-
lyzed to evaluate the dynamic performance of the A/D. The
sine wave input to the part is -0.5dB down from full scale for
all these tests. SNR and SINAD are quoted in dB. The
distortion numbers are quoted in dBc (decibels with respect
to carrier) and DO NOT include any correction factors for
normalizing to full scale.
Signal-to-Noise Ratio (SNR)
SNR is the measured RMS signal to RMS noise at a
specified input and sampling frequency. The noise is the
RMS sum of all of the spectral components except the
fundamental and the first five harmonics.
Signal-to-Noise + Distortion Ratio (SINAD)
SINAD is the measured RMS signal to RMS sum of all other
spectral components below the Nyquist frequency, excluding DC.
Effective Number Of Bits (ENOB)
The effective number of bits (ENOB) is calculated from the
SINAD data by:
ENOB = (SINAD + V_CORR – 1.76 )/6.02
where: V_CORR = 0.5dB
V_CORR adjusts the ENOB for the amount the input is below
fullscale.
Total Harmonic Distortion (THD)
THD is the ratio of the RMS sum of the first 5 harmonic
components to the RMS value of the fundamental input
signal.
2nd and 3rd Harmonic Distortion
This is the ratio of the RMS value of the applicable harmonic
component to the RMS value of the fundamental input signal.
Intermodulation Distortion (IMD)
Nonlinearities in the signal path will tend to generate intermodu-
lation products when two tones, f₁ and f₂, are present on the
inputs. The ratio of the measured distortion terms to the signal
is calculated. The terms included in the calculation are (f₁ + f₂),
(f₁ - f₂), (2f₁), (2f₂), (2f₁ + f₂), (2f₁ - f₂), (f₁ + 2f₂), (f₁ - 2f₂). The
ADC is tested with each tone 6dB below full scale.
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