Key Sheet AD7193 (Analog Devices) - 5

Key Sheet AD7193 FREQUENTLY ASKED QUESTIONS What is the optional internal buffer?
protect the device from possible ESD damage due to handling The multiplexed input channels of the AD7193 are connected to and production. To determine the appropriate ESD precautions, the on-chip buffer amplifier when the device is operated in refer to the AD7193 data sheet for information about the buffered mode and are connected directly to the modulator absolute maximum ratings. when the device is operated in unbuffered mode. In buffered
Is an antialiasing filter required?
mode, the input channel feeds into a high impedance input The analog input is sampled at 307.2 kHz. The digital filter does stage of the buffer amplifier. Therefore, the input can tolerate not provide any rejection at this frequency or at frequencies that significant ranges of source impedances and is tailored for are multiples of 307.2 kHz. Although an external antialiasing direct connection to external resistive-type sensors, such as filter is required to provide rejection at these frequencies, a strain gauges or resistance temperature detectors (RTDs). simple RC filter is sufficient. Typical values for the filter are
What digital filter options are available?
• 1 kΩ resistor in series with each analog input The AD7193 offers a lot of flexibility in the digital filter. The • 0.1 µF capacitor between the analog input pins device has five filter options. The device can be operated with • a sinc3 or sinc4 filter, chop can be enabled or disabled, and zero 0.01 µF capacitor from each input pin to ground latency can be enabled. Finally, an averaging block can be These typical values can be used only when the buffer is included after the sinc filter, which al ows a fast settling mode. enabled. When the buffer is disabled, smaller RC values are The option selected affects the output data rate, settling time, required because larger values can cause gain errors. and 50 Hz/60 Hz rejection.
Can filtering be added to the reference pins? What is 50 Hz and 60 Hz rejection?
The reference input to the AD7193 is not buffered. Therefore, The mains power supply generates interference at 50 Hz or the filtering must be limited on the reference pins because large 60 Hz, with the frequency varying from one country to another. RC values can cause gain errors. The AD7193 data sheet lists The AD7193 has the ability to simultaneously reject 50 Hz and acceptable RC values for use when the analog inputs are 60 Hz signals. The output data rate at which simultaneous 50 Hz unbuffered. Similar values should be used on the reference pins. and 60 Hz rejection occurs depends on the filter type used.
What can the four GPIOs be used for? How do I interface with the part?
The AD7193 has four general-purpose digital outputs: P0, P1, The part can be configured by using a 4-wire SPI interface; this P2, and P3. The pins can be pulled high or low using the interface is also used as the data interface. The SPI interface allows P0DAT to P3DAT bits in the GPOCON register. The logic levels the user to read the status of the part and to change the setup. for these pins are determined by AVDD rather than by DVDD.
Are there any ESD protection schemes that should be
These pins can be used to drive external circuitry, such as an
considered with the AD7193?
external multiplexer. If an external multiplexer is used to These converters are manufactured on a standard CMOS increase the channel count, the multiplexer logic pins can be process; therefore, all standard practices and protection control ed via the AD7193 general-purpose output pins. The schemes that apply to other CMOS devices also apply to these general-purpose output pins can be used to select the active devices. There are ESD protection diodes on al the inputs that multiplexer pin. Rev. 0 | Page 5 of 6 Document Outline General Description Features and Benefits Key Characteristics Fundamental Specifications Noise Sinc4 Chop Disabled Filter Setting Fast Settling Filter Setting Operating the AD7193 Data Interface 4-Wire Serial Interface 3-Wire Serial Interface Data Modes Continuous Conversion Mode (Default) Continuous Read Mode Single Conversion Mode Typical Application Diagram Frequently Asked Questions Learn More and Start Designing Compatible Devices Package Diagram Getting Started