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ADuC7032-8L
Rev. A | Page 19 of 120
TERMINOLOGY
Conversion Rate
The conversion rate specifies the rate at which an output result
is available from the ADC, once the ADC has settled.
The Σ-Δ conversion techniques used on this part mean that
while the ADC front-end signal is oversampled at a relatively high
sample rate, a subsequent digital filter is employed to decimate
the output to give a valid 16-bit data conversion result at output
rates from 1 Hz to 8 kHz.
Note that when software switches from one input to another
(on the same ADC), the digital filter must first be cleared and
then allowed to average a new result. Depending on the configu-
ration of the ADC and the type of filter, this can take multiple
conversion cycles.
Integral Nonlinearity (INL)
Integral nonlinearity is the maximum deviation of any code from a
straight line passing through the endpoints of the transfer function.
The endpoints of the transfer function are zero scale, a point
0.5 LSB below the first code transition; and full scale, a point
0.5 LSB above the last code transition (111 . . . 110 to 111 . . . 111).
The error is expressed as a percentage of full scale.
No Missing Codes
No missing codes is a measure of the differential nonlinearity
of the ADC. The error is expressed in bits and specifies the
number of codes (ADC results) as 2N bits, where N = no missing
codes, guaranteed to occur through the full ADC input range.
Offset Error
Offset error is the deviation of the first code transition ADC
input voltage from the ideal first code transition.
Offset Error Drift
Offset error drift is the variation in absolute offset error with
respect to temperature. This error is expressed as LSBs per °C.
Gain Error
Gain error is a measure of the span error of the ADC. It is a
measure of the difference between the measured span and the
ideal span between any two points in the transfer function.
Output Noise
Output noise is the standard deviation (or 1 × Σ) of ADC output
codes distribution collected when the ADC input voltage is
at a dc voltage. It is expressed as micro root mean square (μ rms).
The output or rms noise can be used to calculate the effective
resolution of the ADC, as defined by the following equation:
Effective Resolution = log2(Full-Scale Range/rms Noise) bits
The peak-to-peak noise is defined as the deviation of codes that
fall within 6.6 × Σ of the distribution of ADC output codes
collected when the ADC input voltage is at dc. The peak-to-
peak noise is, therefore, calculated as 6.6 × the rms noise.
The peak-to-peak noise can be used to calculate the ADC
(noise free, code) resolution for which there is no code flicker
within a 6.6 sigma limit, as defined by the following equation:
Noise Free Code Resolution = log2(Full-Scale Range/
Peak-to-Peak Noise) bits
Table 8. Data Sheet Acronyms
Acronym
Definition
ADC
analog-to-digital converter
ARM
advanced RISC machine
ECU
electronic control unit
JTAG
joint test action group
LDO
low dropout
LIN
local interconnect network
LSB
least significant byte/bit
LVF
low voltage flag
MAC
multiplication accumulation
MCU
microcontroller
MMR
memory mapped register
MSB
most significant byte/bit
PID
protected identifier
PLL
phase-locked loop
POR
power-on reset
PSM
power supply monitor
rms
root mean square