MAX187BMJA View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX187BMJA

+5V, Low-Power, 12-Bit Serial ADCs

Maxim Integrated 

+5V, Low-Power, 12-Bit Serial ADCs

12.2

12.0

11.8

11.6

11.4

11.2

11.0

10.8

10.6

10.4

10.2

1

(UNDERSAMPLED)

10

100

1000

INPUT FREQUENCY (kHz)

Figure 12. Effective Bits vs. Input Frequency

The effective resolution (effective number of bits) the

ADC provides can be determined by transposing the

above equation and substituting in the measured

SINAD: N = (SINAD - 1.76)/6.02. Figure 12 shows the

effective number of bits as a function of the input fre-

quency for the MAX187/MAX189.

Total Harmonic Distortion

If a pure sine wave is sampled by an ADC at greater

than the Nyquist frequency, the nonlinearities in the

ADC’s transfer function create harmonics of the input

frequency present in the sampled output data.

Total Harmonic Distortion (THD) is the ratio of the RMS

sum of all the harmonics (in the frequency band above

DC and below one-half the sample rate, but not includ-

ing the DC component) to the RMS amplitude of the

fundamental frequency. This is expressed as follows:

THD = 20log √ V22 + V32 + V42 + … VN2

V1

where V1 is the fundamental RMS amplitude, and V2

through VN are the amplitudes of the 2nd through Nth

harmonics. The THD specification in the Electrical

Characteristics includes the 2nd through 5th

harmonics.

a. SPI

b. QSPI

I/O

SCK

MISO

+5V

SS

CS

SCK

MISO

+5V

SS

I/O

SK

SI

c. MICROWIRE

CS

SCLK

DOUT

MAX187

MAX189

CS

SCLK

DOUT

MAX187

MAX189

CS

SCLK

DOUT

MAX187

MAX189

Figure 13. Common Serial-Interface Connections to the

MAX187/MAX189

14 ______________________________________________________________________________________

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