MAX1261 Datasheet, PDF (18/20 Pages) Maxim Integrated Products – 250ksps, +3V, 8-/4-Channel, 12-Bit ADCs with +2.5V Reference and Parallel Interface

250ksps, +3V, 8-/4-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
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CLK
WR
RD
HBEN
CONTROL
D7–D0 _BYTE
D7–D0 D11–D8
LOW HIGH
BYTE BYTE
STATE
ACQUISITION
CONTROL BYTE
CONVERSION
D7–D0 D11–D8
LOW HIGH
BYTE BYTE
ACQUISITION
SAMPLING INSTANT
Figure 10. Timing Diagram for Fastest Conversion
Effective Number of Bits
Effective number of bits (ENOB) indicates the global
accuracy of an ADC at a specific input frequency and
sampling rate. An ideal ADC error consists of quantiza-
tion 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
Total harmonic distortion (THD) is the ratio of the RMS
sum of the first five harmonics of the input signal to the
fundamental itself. This is expressed as:
THD =

20 x log _


V₂₂
+
V₃₂
+
V₄₂
+
V₅₂



/ V_{1}
where V₁ is the fundamental amplitude, and V₂ through
V₅ are the amplitudes of the 2nd- through 5th-order har-
monics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of the
RMS amplitude of the fundamental (maximum signal
component) to the RMS value of the next-largest distor-
tion component.
SUPPLIES
+3V
V_LOGIC = +2V/+3V GND
R* = 5Ω
4.7µF
0.1µF
V_DD
GND
COM
+2V/+3V DGND
MAX1261
MAX1263
DIGITAL
CIRCUITRY
*OPTIONAL
Figure 11. Power-Supply and Grounding Connections
Chip Information
TRANSISTOR COUNT: 5781
SUBSTRATE CONNECTED TO GND
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