Rainbow Electronics MAX1139 - Manual (Page 20)

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’s error consists of quanti-
zation noise only. With an input range equal to the
ADC’s full-scale range, calculate the ENOB as follows:
ENOB = (SINAD - 1.76)/6.02
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS
sum of the input signal’s first five harmonics to the fun-
damental itself. This is expressed as:
where V 1 is the fundamental amplitude, and V 2 through V 5
are the amplitudes of the 2nd through 5th order harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of RMS
amplitude of the fundamental (maximum signal compo-
nent) to the RMS value of the next largest distortion
component.
Chip Information
MAX1136/MAX1137 TRANSISTORS COUNT: 11,362
MAX1138/MAX1139 TRANSISTORS COUNT: 12,956
PROCESS: BiCMOS
THD
V V V V
V
= ×
+ + +


















20
2
2
3
2
4
2
5
2
1
log
SINAD dB
SignalRMS
NoiseRMS THDRMS
( ) log = ×
+





 20
MAX1136–MAX1139
2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/12-Channel, 2-Wire Serial 10-Bit ADCs
20 ______________________________________________________________________________________
*OPTIONAL
**AIN11/REF (MAX1138/MAX1139)
*R S
*R S
ANALOG
INPUTS
mC SDA
SCL
GND
V DD
SDA
SCL
AIN0
AIN1
AIN3**/REF
3.3V or 5V
0.1 mF
0.1 mF
5V
R P
C REF
R P
5V
MAX1136
MAX1137
MAX1138
MAX1139
Typical Operating Circuit
SDA
SCL AIN3/REF
1
2
8
7
V DD
GND AIN1
AIN2
AIN0
µMAX
TOP VIEW
3
4
6
5
MAX1136
MAX1137
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
AIN0 AIN8
AIN9
AIN10
AIN11/REF
V DD
GND
SDA
SCL
MAX1138
MAX1139
QSOP
AIN1
AIN2
AIN5
AIN3
AIN4
AIN6
AIN7
Pin Configurations
Selector Guide
PART
INPUT
CHANNELS
INTERNAL
REFERENCE
(V)
SUPPLY
VOLTAGE (V)
MAX1136EUA 4 4.096 4.5 to 5.5
MAX1137EUA 4 2.048 2.7 to 3.6
MAX1138EEE 12 4.096 4.5 to 5.5
MAX1139EEE 12 2.048 2.7 to 3.6