Analog Devices: CN0255 Reference Design for A Complete Single-Supply, 16-Bit, 100 kSPS PulSAR ADC System Dissipates 8 mW

atomar — Tue, 23 Apr 2013 07:40:16 GMT

Current Revision posted to Documents by atomar on 4/23/2013 7:40:16 AM

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Kit Overview

In most systems, there are tradeoffs between performance and low power. The focus of this circuit design EVAL-CN0255-SDPZEVAL-CN0255-SDPZ is to explore a few of these tradeoffs and still achieve low power (8 mW typical) and high performance in a 16-bit, 100 kSPS data acquisition system.

This circuit uses the AD7988-1AD7988-1, a low power (350 μA) PulSAR® analog-to-digital converter (ADC), driven directly from the ADA4841-1ADA4841-1 high performance, low voltage, low power op-amp. This amplifier was chosen for its excellent dynamic performance and its ability to operate with a single-supply voltage and to provide a rail-to-rail output. In addition, the input common mode voltage range includes the negative rail.

The AD7988-1 ADC requires an external voltage reference between 2.4 V and 5.1 V. In this application, the voltage reference chosen was the ADR4525ADR4525 precision 2.5 V reference. The EVAL-CN0255-SDPZEVAL-CN0255-SDPZ evaluation board was interfaced to the System Demonstration Platform (SDP-B), EVAL-SDP-CB1ZEVAL-SDP-CB1Z, where the ADC SPI-compatible serial interface was connected to the DSP SPORT interface. The ADCs SPI interface features the ability to daisy-chain several ADCs on a single 3-wire bus. It is compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate VIO supply pin.

The heart of this circuit is the AD7988-1, a 16-bit, 100 kSPS successive approximation, ADC that operates from a single VDD power supply. It contains a low power, high speed, 16-bit sampling ADC and a versatile serial port interface (SPI). On the CNV rising edge, it samples an analog input, IN+, between 0 V to REF with respect to the ground sense pin, IN−. The reference voltage, REF, is applied externally and can be set independent of the supply voltage, VDD.

Key Applications: Electronic Test & Measurement, Programmable Logic Controllers/ Distributed Control Systems

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Development Tools

EVAL-CN0255-SDPZEVAL-CN0255-SDPZ Evaluation Board
System Demonstration Board (EVAL-SDP-CB1ZEVAL-SDP-CB1Z)

- Blackfin Processor ADSP-BF527
- USB 2.0 Interface to PC
- JTAG header footprint
- 32MB SDRAM
- 2 x Small Footprint 120 Pin Connectors
- Configurable Peripheral Interfaces - SPI - SPORT - I2C - GPIOs - Parallel - Timers

Function generator/signal source, such as Audio Precision SYS-2522 used in these tests.
Power supply, 2.5 V and 4 V
PC with USB port, USB cable, and installed 10-lead PulSAR software

Technical Documents

Learning Center

Type	Description
User Manual	ADI: User Manual for CN-0255 A Complete Single-Supply, 16-Bit, 100 kSPS PulSAR ADC System Dissipates 8 mW
User Guide	ADI: User Guide for EVAL-SDP-CB1Z
Datasheet	ADI: Datasheet for AD7988-1/AD7988-5: 16-Bit Lower Power PulSAR ADCs in MSOP/LFCSP (QFN) (Rev C)
Datasheet	ADI: Datasheet for ADA4841-1/ADA4841-2: Low Power, Low Noise and Distortion, Rail-to-Rail Output Amplifiers (Rev E, 12/2010)
Datasheet	ADI: Datasheet for ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550: Ultralow Noise, High Accuracy Voltage References (Rev 0)
Datasheet	ADI: Datasheet for AD8031/AD8032 - 2.7 V, 800 μA, 80 MHz Rail-to-Rail I/O Amplifiers (Rev D)

Design Elements

Type	Description
Schematics	ADI: Schematics for EVAL-CN0255-SDPZ Evaluation Board
Layout	ADI: Layout for EVAL-CN0255-SDPZ
BOM	ADI: Bill Of Material (BOM) for EVAL-CN0255-SDPZ Evaluation Board

Video

www.youtube.com/watch

Kit Features

Key Features for EVAL-CN0255-SDPZEVAL-CN0255-SDPZ Evaluation Board are as below:

It uses the AD7988-1AD7988-1, a low power (350 μA) PulSAR® analog-to- digital converter (ADC),
- Low power dissipation: - AD7988-1: 700 uW @ 100 kSPS
- 16-bit resolution with no missing codes
- Throughput: 100kSPS
- INL: ±0.6 LSB typical, ±1.25 LSB maximum
- SINAD: 91.25 dB @ 10 kHz
- THD: -114dB @ 10 kHz
- No pipeline delay
AD7988-1 is driven directly from the ADA4841-1ADA4841-1 high performance, low voltage, low power op-amp.
- Low power: 1.1 mA/amp
- Low wideband noise 2.1 nV/√Hz, 1.4 pA/√Hz
- Low 1/F noise: 7 nV/√Hz @ 10 Hz, 13 pA/√Hz @ 10 Hz
- Low distortion: -105 dBc @ 100 kHz, V_O = 2 V p-p
The voltage reference - ADR4525ADR4525 precision 2.5 V reference.
- Maximum temperature coefficient (TC): 2 ppm / °C
- Output noise (0.1 – 10 Hz): < 1.25 μVp-p @ 2.5 VOUT typ.
- Initial output voltage error: ± 0.02% maximum
- Input voltage range: 3 to 15 V
- Output current: +10 mA source / -10 mA sink
- Low quiescent current: 950 μA (max)

Kit Contents

The Analog Devices EVAL-CN0255-SDPZEVAL-CN0255-SDPZ kit is supplied with below contents:

Evaluation Board

Tags: ad7988-1, adr4525, ada4841-1, analog_devices, eval-cn0255-sdpz