AS1545
Datasheet - Terminology
8 Terminology
Acquisition Time
The Acquisition time is the time needed by the ADC to accurately acquire the analog input voltage in the internal
sampling capacitor. During this time the ADC is in track mode.
Conversion Time
The Conversion Time is the time that the ADC needs to convert an acquired analog input into a corresponding digital
code. A Successive Approximation Register ADC usually needs a number of clocks dependant on the resolution.
During this time the ADC is in hold mode.
Throughput / Sample Rate
The Throughput or Sample Rate is the number of conversions performed by an ADC per second. It is usually specified
in Samples Per Second (SPS). The Throughput or Sample Rate is the reciprocal of the sum of Acquisition Time and
Conversion Time.
Aperture Delay
The Aperture Delay defines the time between the falling edge of CSN and the actual Sampling Instant. The Aperture
Delay Matching defines the maximum deviation of Aperture Delays across all 6 channels of one ADC.
Aperture Jitter
The Aperture Jitter is the deviation of the actual Sampling Instant. This deviation is totally random and the standard
deviation of the distribution is calculated with one sigma.
Differential Nonlinearity (DNL)
The Differential Nonlinearity is the deviation between the actual code widths to the ideal code widths of 1 LSB,
comparing all contiguous codes in the ADC. The ADC is specified according to its maximum and minimum DNL values
across all codes. A DNL value equal to -1 indicates a missing code in the transfer function.
Integral Nonlinearity (INL)
The Integral Nonlinearity measures the deviation from the actual transfer function to the best straight line that
minimizes the INL worst case values.
Offset Error
The Offset Error defines the absolute deviation of the first code transition (0x000h) to (0x001h) from the ideal input
voltage (AGND + 0.5 LSB) in Single Ended and Pseudo Differential Mode (binary output coding).
VIN
VREF
---------------
Offset Error =
× 4096 – AVG(MeasuredCodes)
Offset Error Match
The Offset Error Match defines the maximum deviation of the Offset Errors across all 6 channels of VIN in Single
Ended and Pseudo Differential Mode (binary output coding).
Gain Error
The Gain Error defines the absolute deviation of the last code transition (0xFFEh) to (0xFFFh) from the ideal input
voltage (VREF – 1.5 LSB) in Single Ended and Pseudo Differential Mode. The Offset Error is compensated.
VIN
VREF
---------------
Gain Error = OffsetError – AVG(MeasuredCodes) –
× 4096
Gain Error Match
The Gain Error Match defines the maximum deviation of the Gain Errors across all 6 channels of VIN in Single Ended
and Pseudo Differential Mode (binary output coding).
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