These low power ADCs offer very high performance from 14-bits up to 18-bits with throughputs ranging from 100ksps to 1.3MSPS. The boards are designed to demonstrate the ADC's performance and to provide an easy digital interface for a variety of system applications. A full description of these products are available in their respective data sheets and should be consulted when utilizing the boards. To purchase hardware, please visit our website.
|Products||Resolution||ADC Throughput*||Input Stage||Driver Amplifier||PMOD Part Number|
|AD7942||14-Bit||250 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7942-PMDZ|
|AD7946||14-Bit||500 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7946-PMDZ|
|AD7988-1||16-Bit||100 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7988-1-PMDZ|
|AD7685||16-Bit||250 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7685-PMDZ|
|AD7687||16-Bit||250 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7687-PMDZ|
|AD7691||16-Bit||250 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7691-PMDZ|
|AD7686||16-Bit||500 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7686-PMDZ|
|AD7688||16-Bit||500 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7688-PMDZ|
|AD7693||16-Bit||500 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7693-PMDZ|
|AD7988-5||16-Bit||500 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7988-5-PMDZ|
|AD7980||16-Bit||1000 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7980-PMDZ|
|AD7983||16-Bit||1333 kSPS||Unipolar, Single-Ended Input||ADA4841||EVAL-AD7983-PMDZ|
|AD7690||18-Bit||400 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7690-PMDZ|
|AD7982||18-Bit||1000 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7982-PMDZ|
|AD7984||18-Bit||1333 kSPS||Unipolar, Differential Input||ADA4841||EVAL-AD7984-PMDZ|
* The throughput of your PulSAR ADC will be limited to the SPI bus speed of your platform. For example if you are using the SDP platform the max bus rate on the SPI is 30 MHz.
The PMOD board is small in size with dimensions approximately 1 inch in width by 3 inches in length. There are a few areas of the hardware I'd like to point out for you, in order to use the board.
Typically when using a PMOD board the power for the module comes directly from the host board it is connected to. The power is generally capable of providing up to 100 mA at 3.3V, and for complete power specifications please click here.
In the case of the high precision, successive approximation ADC's architecture, it was required to provide low noise external power supplies to obtain datasheet results. The ADC's are driven by precision amplifiers which are also optimized for noise and power. In order to enable those amplifiers to provide zero and full scale inputs to the ADC, power supplies above and below the ADC input range were needed.
With all these factors combined, the board was designed using external power supplies of -2.5V, GND (of course), and 7.5V. These supplies provide the power for the entire PMOD board, so even though power is coming in through the PMOD connector, it's not actually powering the components on the board.
For the input signals coming into the PMOD board, SMB connectors were chosen to help minimize the noise at the input. There are two(2) SMB connectors per board, and thats because there are both positive(+) and negative(-) inputs to each converter. This will provide the user with the cleanest input signal possible, an fully utilize the resolution and speed of the converters.
Each of the converters also has a combination of single ended inputs, differential inputs, or pseudo-differential inputs. So in order to determine the input style of your converter it is imperative to look at the datasheet for the device you are using. The datasheet of any device should always be followed before using it in an application or on a board
The PMOD interface is a series of standardized digital interfaces for various digital communication protocols such as SPI, I2C, and UART. These interface types were standardized by Digilent, which is now a division of National Instruments. Complete details on the PMOD specification can be found here.
The specific interface used for the PulSAR PMOD boards is the extended SPI. In general ADI has adopted the extended SPI connector for all PMOD devices which have an SPI interface. It provides flexibility to add interrupts, general purpose I/O, resets, and other important digitally controlled functions.
Above is the connection to each of the PulSAR PMOD boards to the SPI PMOD connector. Each of the PulSAR PMOD boards is hardware configured in a 3-wire mode with no busy indicator. This configuration can be better explained in the datasheet if you desire to learn more. This basically means that the only signals that go between the converter and the processor are the CNV (similar to a chip select in this mode), SCLK (serial Clock), and MISO (serial data out). There are no registers internal to the PulSAR ADC's, so there is no need for a data input line, the data just streams out using the CNVST pin.
Using any of the PulSAR ADC PMOD boards is very simple. To get started evaluating the ADCs, you are going to need the following equipment:
Evaluating the PulSAR ADC PMOD boards is very simple. Using the required equipment follow these simple steps to get the evaluation working. Please make sure you completely unplug all the boards before beginning.
The PulSAR ADC PMOD boards have a special version of software needed to run the evaluation, so please install this version of the software.
Once you download and install the software, you'll be able to launch the application and communicate with the hardware setup. When you open up the application the front screen will look like the following:
The following is the description of how to use the user panel:
The following screen shot is an example of using the AD7980 ADC, and looking at the frequency domain to view a 10kHz input sine wave. This tab provided several frequency domain calculations such as SINAD, THD, SNR.
Rev 0 to Rev A
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