MAX7651 Datasheet, PDF (34/36 Pages) Maxim Integrated Products – Flash Programmable 12-Bit Integrated Data-Acquisition Systems

Flash Programmable 12-Bit Integrated
Data-Acquisition Systems
CLK
CPU
CYCLE
STOP
PCON.1
ALE
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
~PSEN
MEM
n
n+1
n+2
ADDR
Figure 12. Stop Mode Timing
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between an
actual step width and the ideal value of 1LSB. A DNL
error specification of less than 1LSB guarantees no
missing codes and a monotonic transfer function.
Offset Error
The offset error is the difference between the ideal and
the actual offset points. For an ADC, the offset point is
the midstep value when the digital output is zero.
Gain Error
The gain or full-scale error is the difference between
the ideal and actual gain points on the transfer function,
after the offset error has been canceled out. For an
ADC the gain point is the midstep value when the digi-
tal output is full-scale.
Signal-To-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital
samples, SNR is the ratio of full-scale analog input
(RMS value) to the RMS quantization error (residual
error). The ideal theoretical minimum analog-to-digital
noise is caused by quantization error only and results
directly from the ADCs resolution (N Bits):
SNR = (6.02 x N + 1.76)dB
In reality, there are other noise sources besides quanti-
zation noise including thermal noise, reference noise,
clock jitter. Therefore, SNR is computed by taking the
ratio of the RMS signal to the RMS noise which includes
all spectral components minus the fundamental, the
first five harmonics, and the DC offset.
Signal-To-Noise Plus Distortion (SINAD)
Signal-To-Noise Plus Distortion is the ratio of the funda-
mental input frequency’s RMS amplitude to RMS equiv-
alent of all other ADC output signals.
SINAD (dB) = 20 x log (Signal_RMS / Noise_RMS)
Effective Number Of Bits (ENOB)
ENOB indicates the global accuracy of an ADC at a
specific input frequency and sampling rate. An ideal
ADCs error consists of quantization noise only. With an
input range equal to the full-scale range of the ADC,
calculate the effective number of bits as follows:
ENOB = (SINAD - 1.76) / 6.02
Total Harmonic Distortion (THD)
THD is the ratio of the RMS sum of the first five harmon-
ics of the input signal to the fundamental itself. This is
expressed as:
( ) ^

THD = 20 × log^
V₂₂ + V₃₂ + V₄₂ + V₅₂





V₁


where V1 is the fundamental amplitude, and V2 through
V5 are the amplitudes of the 2nd- through 5th-order
harmonics.
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of RMS amplitude of the fundamental
maximum signal component to the RMS value of the
next largest distortion component.
Chip Information
TRANSISTOR COUNT: 358,000
PROCESS: CMOS
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