EVAL-AD7986EBZ

EVAL-AD7986EBZ Datasheet

q Full-featured evaluation board for the AD7944/AD7985/AD7986 q PC Control in conjunction with the converter and evaluation development board

Part	Datasheet
EVAL-AD7986EBZ	EVAL-AD7986EBZ (pdf)

Related Parts	Information
EVAL-AD7985EBZ	EVAL-AD7985EBZ
EVAL-AD7944EBZ	EVAL-AD7944EBZ

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One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106 • Tel • Fax • User Guide for the AD7944/AD7985/AD7986, 14-/16-/18-Bit ADCs q Full-featured evaluation board for the AD7944/AD7985/AD7986 q PC Control in conjunction with the converter and evaluation development board EVAL-CED1Z q PC software for control and data analysis of time and frequency domain q Versatile analog signal conditioning circuitry q On-board reference, clock oscillator, and buffers q Standalone capability System Requirements q Windows XP SP2 q Windows Vista q Windows 7 q USB Port Software needed q Enclosed CD or available via Website download Evaluation Kit Contents q Evaluation board as ordered EVAL-AD7944EDZ, EVAL-AD7985EDZ, or EVAL-AD7986EDZ q Software CD Documents required q AD7944 data sheet q AD7985 data sheet q AD7986 data sheet Equipment required q Precision source r DC source low noise for checking different input ranges r AC source low distortion . q Band-pass filter suitable for 16-bit or 18-bit testing value based on signal frequency . q SMB cable q Evaluation converter evaluation and development board, EVAL-CED1Z. q World-compatible 7 V dc supply enclosed with EVAL-CED1Z The EVAL-AD79XXEDZ is an evaluation board for the 20-lead AD7944 14-bit , AD7985 16-bit , and AD7986 18-bit analog-to-digital converters ADCs . On-board components include a high precision, buffered band gap V reference ADR435 , reference buffers AD8032 , a signal conditioning circuit with two op-amps AD8021 , and an FPGA for deserializing the serial conversion results. The evaluation board interfaces to the CED capture board by using a 96-pin DIN connector. In addition, SMB connectors, J1 and J2, are provided for the low noise analog signal source. Quickstart Install the software from the enclosed CD or by downloading from the Analog Devices, Inc., Website, at Ensure the evaluation board is disconnected from the USB port of the PC while installing the software. A PC restart may be required after installation. Connect the EVAL-CED1Z board to the evaluation board as shown in Figure Connect the power supply adapter included in the kit to Connecter J4 on the EVAL-CED1Z board. Connect the EVAL-CED1Z board to the PC via the USB cable. Choose to automatically search for the drivers for the EVAL-CED1Z board if prompted by the operating system. For Windows XP you may need to search for the EVAL-CED1Z drivers. Launch the EVAL-AD7944/AD7985/AD7986EDZ software from the Analog Devices subfolder in the Programs menu. Select the appropriate device from the drop down menu AD7944, AD7985, or AD7986. Apply a signal source to the AIN+/AIN− SMB inputs on the evaluation board. Configure the signal source for the appropriate signal applied to the input of the device. Capture data by initiating a single capture F3 or a continuous capture F4 . See details on configuring the software in the Running the ADC Analysis Software section. Note that the measurements made by Analog Devices use the Audio Precision SYS-2522. Figure Hardware up the Evaluation Board Evaluation Board Hardware The low power, AD7944/AD7985/AD7986 ADCs offer very high performance of up to MSPS AD7986 and MSPS AD7944and AD7985 throughput rates using a flexible parallel interface on the 96-pin interface to the EVAL-CED1Z board. The evaluation board is designed to demonstrate the performance of the ADC and to provide an easy-to-understand interface for a variety of system applications. The evaluation board is ideal for use with the Analog Devices Converter and Evaluation Development EVAL-CED1Z CED . The design offers the flexibility of applying external control signals and is capable of generating conversion results on parallel 16-bit wide buffered outputs. The figure above shows the EVAL-AD7944/AD7985/AD7986EBZ evaluation board. The on-board FPGA, U3, provides the necessary control signals for conversion and deserializes the serial data as the EVAL-CED1Z board uses a parallel interface. The evaluation board is a flexible design that enables the user to choose among many different board configurations, analog signal conditioning, reference, and different modes of conversion data. This evaluation board is a 6-layer board carefully laid out and tested to demonstrate the specific high accuracy performance of the AD7944, AD7985, and AD7986. Figure 23 to Figure 28 show the schematics of the evaluation board. Device Description The AD7944 is a 14-bit, MSPS successive approximation analog-to-digital converter SAR ADC , whereas the AD7985 is a 16-bit version of the SAR ADC. The AD7986is an 18-bit 2 MSPS SAR ADC. These ADCs are low power and high speed and include an internal conversion clock, an internal reference and buffer , error correction circuits, and a versatile serial interface port. On the rising edge of CNV, the ADC samples an analog input, IN+, between 0 V and REF with respect to the ground sense, IN−. The ADCs feature a very high sampling rate turbo mode TURBO is high and a reduced power normal mode TURBO is low for low power applications where the power is scaled with the throughput. A full description of these products is available in their respective data sheets and should be consulted when using this evaluation board. Power Supplies Power is supplied to the board through P3 when used with the EVAL-CED1Z. Each supply is decoupled at the point where it enters the board and again at each device. A single ground plane on this board minimizes the effect of high frequency noise interference. Standalone Operation The evaluation board can be used in standalone mode without the CED controller board. In this case, power supplies need to be applied to the board at P4 or at the relevant test points. At a minimum, the board requires ±5 V, +12 V, +7 V, or + V. See Figure 23 for details regarding power supply connections. Grounding The evaluation board ground plane is separated into two sections a plane for the digital interface circuitry and an analog plane for the analog input and external reference circuitry. To attain high resolution performance, the board was designed to ensure that all digital ground return paths do not cross the analog ground return paths by connecting the planes together directly under the converter. Conversion Control The on-board FPGA performs a number of digital functions, one of them being the deserialization of the serial conversion results as the CED data capture boards uses a 16-bit parallel interface. If desired, the deserialized data can be monitored on the 96-pin edge connecter, P1, BD[15:0]. The CED uses a buffered busy signal, BBUSY, as the general interrupt for data. Analog Inputs The analog inputs to the evaluation board are J1, J2, and SMB push on . These inputs are buffered with dedicated amplifier circuitry A2, A3, and discretes to allow configuration changes such as positive or negative gain, input range scaling, filtering, addition of a dc component, and use of different op-amps and supplies. The analog input amplifiers are set as unity-gain buffers at the factory. The supplies are selectable with solder pads and are set for the +7 V to −5 V ranges. The default configuration sets both A2 and A3 at midscale generated from either a buffered reference voltage divider or the internal reference of the ADC. The evaluation board is factory configured for providing either a single-ended path or a fully differential path. Because the AD7986 is differential, both inputs and amplifier circuits are used to buffer the IN+ and IN- inputs of the ADCs. For the AD7944 and AD7985 evaluation boards, only the J2, A3, and associated circuitry is used in the path. For dynamic performance, an FFT test can be executed by applying a very low distortion ac source. For low frequency testing, an audio precision source can be used directly because the outputs on these are isolated. Set the audio precision outputs for balanced and floating. Although different sources can be used, most are single ended and use a fixed output resistance. Because the evaluation board uses the amplifiers in unity gain, the noninverting input has a common-mode input with a 590 Ω series resistor, which needs to be taken into account when directly connecting a source voltage divider . Serial Interface

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One Technology Way
• P.O. Box 9106
• Norwood, MA 02062-9106
• Tel
• Fax
•

User Guide for the AD7944/AD7985/AD7986, 14-/16-/18-Bit ADCs
q Full-featured evaluation board for the AD7944/AD7985/AD7986 q PC Control in conjunction with the converter and evaluation development board

EVAL-CED1Z q PC software for control and data analysis of time and frequency domain q Versatile analog signal conditioning circuitry q On-board reference, clock oscillator, and buffers q Standalone capability

System Requirements
q Windows XP SP2 q Windows Vista q Windows 7 q USB Port

Software needed
q Enclosed CD or available via Website download

Evaluation Kit Contents
q Evaluation board as ordered EVAL-AD7944EDZ, EVAL-AD7985EDZ, or EVAL-AD7986EDZ q Software CD

Documents required
q AD7944 data sheet q AD7985 data sheet q AD7986 data sheet

Equipment required
q Precision source r DC source low noise for checking different input ranges r AC source low distortion .
q Band-pass filter suitable for 16-bit or 18-bit testing value based on signal frequency . q SMB cable q Evaluation converter evaluation and development board, EVAL-CED1Z. q World-compatible 7 V dc supply enclosed with EVAL-CED1Z

The EVAL-AD79XXEDZ is an evaluation board for the 20-lead AD7944 14-bit , AD7985 16-bit , and AD7986 18-bit analog-to-digital converters ADCs . On-board components include a high precision, buffered band gap V reference ADR435 , reference buffers AD8032 , a signal conditioning circuit with two op-amps AD8021 , and an FPGA for deserializing the serial conversion results. The evaluation board interfaces to the CED capture board by using a 96-pin DIN connector. In addition, SMB connectors, J1 and J2, are provided for the low noise analog signal source.

Quickstart

Install the software from the enclosed CD or by downloading from the Analog Devices, Inc., Website, at

Ensure the evaluation board is disconnected from the USB port of the PC while installing the software.

A PC restart may be required after installation. Connect the EVAL-CED1Z board to the evaluation board as shown in Figure Connect the power supply adapter included in the kit to Connecter J4 on the EVAL-CED1Z board. Connect the EVAL-CED1Z board to the PC via the USB cable.

Choose to automatically search for the drivers for the EVAL-CED1Z board if prompted by the operating system.

For Windows XP you may need to search for the EVAL-CED1Z drivers. Launch the EVAL-AD7944/AD7985/AD7986EDZ software from the Analog Devices subfolder in the

Programs menu. Select the appropriate device from the drop down menu AD7944, AD7985, or AD7986. Apply a signal source to the AIN+/AIN− SMB inputs on the evaluation board. Configure the signal source for the appropriate signal applied to the input of the device. Capture data by initiating a single capture F3 or a continuous capture F4 . See details on configuring the software in the Running the ADC Analysis Software section. Note that the measurements made by Analog Devices use the Audio Precision SYS-2522.

Figure Hardware up the Evaluation Board

Evaluation Board Hardware

The low power, AD7944/AD7985/AD7986 ADCs offer very high performance of up to MSPS AD7986 and MSPS AD7944and AD7985 throughput rates using a flexible parallel interface on the 96-pin interface to the EVAL-CED1Z board. The evaluation board is designed to demonstrate the performance of the ADC and to provide an easy-to-understand interface for a variety of system applications. The evaluation board is ideal for use with the Analog Devices Converter and Evaluation Development EVAL-CED1Z CED . The design offers the flexibility of applying external control signals
and is capable of generating conversion results on parallel 16-bit wide buffered outputs. The figure above shows the EVAL-AD7944/AD7985/AD7986EBZ evaluation board. The on-board FPGA, U3, provides the necessary control signals for conversion and deserializes the serial data as the EVAL-CED1Z board uses a parallel interface. The evaluation board is a flexible design that enables the user to choose among many different board configurations, analog signal conditioning, reference, and different modes of conversion data. This evaluation board is a 6-layer board carefully laid out and tested to demonstrate the specific high accuracy performance of the AD7944, AD7985, and AD7986. Figure 23 to Figure 28 show the schematics of the evaluation board.

Device Description

The AD7944 is a 14-bit, MSPS successive approximation analog-to-digital converter SAR ADC , whereas the AD7985 is a 16-bit version of the SAR ADC. The AD7986is an 18-bit 2 MSPS SAR ADC. These ADCs are low power and high speed and include an internal conversion clock, an internal reference and buffer , error correction circuits, and a versatile serial interface port. On the rising edge of CNV, the ADC samples an analog input, IN+, between 0 V and REF with respect to the ground sense, IN−. The ADCs feature a very high sampling rate turbo mode TURBO is high and a reduced power normal mode TURBO is low for low power applications where the power is scaled with the throughput. A full description of these products is available in their respective data sheets and should be consulted when using this evaluation board.

Power Supplies

Power is supplied to the board through P3 when used with the EVAL-CED1Z. Each supply is decoupled at the point where it enters the board and again at each device. A single ground plane on this board minimizes the effect of high frequency noise interference.

Standalone Operation

The evaluation board can be used in standalone mode without the CED controller board. In this case, power supplies need to be applied to the board at P4 or at the relevant test points. At a minimum, the board requires ±5 V, +12 V, +7 V, or + V. See Figure 23 for details regarding power supply connections.

Grounding

The evaluation board ground plane is separated into two sections a plane for the digital interface circuitry and an analog plane for the analog input and external reference circuitry. To attain high
resolution performance, the board was designed to ensure that all digital ground return paths do not cross the analog ground return paths by connecting the planes together directly under the converter.

Conversion Control

The on-board FPGA performs a number of digital functions, one of them being the deserialization of the serial conversion results as the CED data capture boards uses a 16-bit parallel interface. If desired, the deserialized data can be monitored on the 96-pin edge connecter, P1, BD[15:0]. The CED uses a buffered busy signal, BBUSY, as the general interrupt for data.

Analog Inputs

The analog inputs to the evaluation board are J1, J2, and SMB push on . These inputs are buffered with dedicated amplifier circuitry A2, A3, and discretes to allow configuration changes such as positive or negative gain, input range scaling, filtering, addition of a dc component, and use of different op-amps and supplies. The analog input amplifiers are set as unity-gain buffers at the factory. The supplies are selectable with solder pads and are set for the +7 V to −5 V ranges. The default configuration sets both A2 and A3 at midscale generated from either a buffered reference voltage divider or the internal reference of the ADC. The evaluation board is factory configured for providing either a single-ended path or a fully differential path. Because the AD7986 is differential, both inputs and amplifier circuits are used to buffer the IN+ and IN- inputs of the ADCs. For the AD7944 and AD7985 evaluation boards, only the J2, A3, and associated circuitry is used in the path. For dynamic performance, an FFT test can be executed by applying a very low distortion ac source. For low frequency testing, an audio precision source can be used directly because the outputs on these are isolated. Set the audio precision outputs for balanced and floating. Although different sources can be used, most are single ended and use a fixed output resistance. Because the evaluation board uses the amplifiers in unity gain, the noninverting input has a common-mode input with a 590 Ω series resistor, which needs to be taken into account when directly connecting a source voltage divider .

Serial Interface

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Datasheet ID: EVAL-AD7986EBZ 517746