ALLGEMEINE BESCHREIBUNG

The AD7671 is a 16-bit, 1 MSPS, charge redistribution SAR, analog-to-digital converter that operates from a single 5 V power supply. It contains a high speed 16-bit sampling ADC, a resistor input scaler that allows various input ranges, an internal conversion clock, error correction circuits, and both serial and parallel system interface ports. The AD7671 is hardware factory-calibrated and is comprehensively tested to ensure such ac parameters as signal-to-noise ratio (SNR) and total harmonic distortion (THD), in addition to the more traditional dc parameters of gain, offset, and linearity. It features a very high sampling rate mode (Warp), a fast mode (Normal) for asynchronous conversion rate applications, and, for low power applications, a reduced power mode (Impulse) where the power is scaled with the throughput.

 

PRODUKT-HIGHLIGHTS

  1. Fast Throughput The AD7671 is a very high speed (1 MSPS in Warp Mode and 800 kSPS in Normal Mode), charge redistribution, 16-bit SAR ADC.
  1. Single-Supply Operation The AD7671 operates from a single 5 V supply, dissipates only 112 mW typical, even lower when a reduced throughput is used with the reduced power mode (Impulse) and a powerdown mode.
  2. Superior INL The AD7671 has a maximum integral nonlinearity of 2.5 LSB with no missing 16-bit code.
  1. Serial or Parallel Interface Versatile parallel (8 bits or 16 bits) or 2-wire serial interface arrangement compatible with both 3 V or 5 V logic.

 

FEATURES

Throughput

1 MSPS (Warp Mode)

800 kSPS (Normal Mode)

INL: 2.5 LSB Max ( 0.0038% of Full Scale)

16-Bit Resolution with No Missing Codes

S/(N+D): 90 dB Typ @ 250 kHz

THD: –100 dB Typ @ 250 kHz

Analog Input Voltage Ranges

Bipolar: 10 V, 5 V, 2.5 V

Unipolar: 0 V to 10 V, 0 V to 5 V, 0 V to 2.5 V

Both AC and DC Specifications

No Pipeline Delay

Parallel (8/16 Bits) and Serial 5 V/3 V Interface

SPI/QSPI™/MICROWIRE™/DSP Compatible

Single 5 V Supply Operation

Power Dissipation

112 mW Typical

15 W @ 100 SPS

Power-Down Mode: 7 W Max

Package: 48-Lead Quad Flatpack (LQFP)

Package: 48-Lead Chip Scale (LFCSP)

Pin-to-Pin Compatible Upgrade of the AD7665/AD7664

 

ANWENDUNGEN

Data Acquisition

Communication

Instrumentierung

Spectrum Analysis

Medical Instruments

Prozesskontrolle

 

DEFINITION OF SPECIFICATIONS

Integral Nonlinearity Error (INL) Linearity error refers to the deviation of each individual code from a line drawn from “negative full scale” through “positive full scale.” The point used as negative full scale occurs 1/2 LSB before the first code transition. Positive full scale is defined as a level 1 1/2 LSB beyond the last code transition. The deviation is measured from the middle of each code to the true straight line.

Differential Nonlinearity Error (DNL)

In an ideal ADC, code transitions are 1 LSB apart. Differential nonlinearity is the maximum deviation from this ideal value. It is often specified in terms of resolution for which no missing codes are guaranteed.

Full-Scale Error

The last transition (from 011 …10 to 011 . . . 11 in twos complement coding) should occur for an analog voltage 1 1/2 LSB below the nominal full scale (2.499886 V for the ±2.5 V range). The full-scale error is the deviation of the actual level of the last transition from the ideal level.

Bipolar Zero Error

The difference between the ideal midscale input voltage (0 V) and the actual voltage producing the midscale output code.

Unipolar Zero Error

In Unipolar Mode, the first transition should occur at a level 1/2 LSB above analog ground. The unipolar zero error is the deviation of the actual transition from that point.

Spurious-Free Dynamic Range (SFDR)

The difference, in decibels (dB), between the rms amplitude of the input signal and the peak spurious signal.

Total Harmonic Distortion (THD)

The rms sum of the first five harmonic components to the rms value of a full-scale input signal, expressed in decibels.

Signal-to-Noise Ratio (SNR)

The ratio of the rms value of the actual input signal to the rms sum of all other spectral components below the Nyquist frequency, excluding harmonics and dc. The value for SNR is expressed in decibels.

Signal-to-(Noise + Distortion) Ratio (S/[N+D]) The ratio of the rms value of the actual input signal to the rms sum of all other spectral components below the Nyquist frequency, including harmonics but excluding dc. The value for

S/(N+D) is expressed in decibels.

Aperture Delay

A measure of the acquisition performance measured from thefalling edge of the CNVST input to when the input signal is held for a conversion.

Transient Response

The time required for the AD7671 to achieve its rated accuracy after a full-scale step function is applied to its input.