Maxim’s MAX22530 self-powered isolated analog-to-digital converters (ADCs) are galvanically isolated, 4-channel, multiplexed, 12-bit ADCs in the MAXSafe family product line. An integrated, isolated DC/DC converter powers all field-side circuitry, enabling field-side diagnostics even when no input signal is present.
It’s pretty common to have a built-in multiplexed ADC in microcontrollers these days – to the extent that usually folks only wire up an external ADC when there’s some particular capability they need – high accuracy, wide range, programmable-gain, etc. This ADC has a lot of great specs going for it – 4 channel so you can monitor a few different points or take some differential measurements if needed, 12-bit is a nice balance that gives good precision (4096 points, which on a 5V measurement scale is about 1.2mV, and 20 kSPS over SPI for easy integration and up to 10KHz signal bandwidth.
Most importantly, it’s got full 5kVRMS isolation between the measurement side and the ADC/logic side (the ADC is on the isolated side). And not only is the digital side isolated but you also get an isolated DC/DC which powers the ADC half – it’s only up to 5V and it’s only 10mA or so, so it’s not for power, just for reference. Still, that means you can tie the ‘field’ half to whatever ground you like and take your measurements without worrying about connecting the power supplies together.
There are also some nice extras for higher-reliability practices. Most ADCs are simple clock-in-data-out devices, but this one has error checks for common mistakes that can occur when doing data capture in electrically-noisy environments:
Diagnostic and Fault Reporting Features:
The MAX22530–MAX22532 continuously monitor multiple possible fault conditions, and a hardware alert is provided through the open drain pin, which asserts low when an enabled fault is detected. The possible faults are: ADC functionality error, SPI framing error, CRC errors from SPI communications, and loss of internal isolated data stream.
This makes the MAX22530 a super-easy-and-reliable to use ADC for any data acquisition when you are monitoring power systems that may have non-earth-ground references, high side voltage measurements that are out-of-range for a regular ADC’s common modes, or when there’s a lot of digital noise that you want to make sure doesn’t get coupled in. We love these simple and effective parts – they do one thing well, and don’t need special treatment to get the job done.
And best of all, the MAX22530 is in stock right now at Digi-Key for immediate shipment. There’s an eval board we picked up as well, which comes with an FT2232 USB-to-SPI interface and Windows software for quick testing to verify it will function in the environment you’re working in. Book today and you can be taking fully-isolated ADC measurements by tomorrow morning!
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