This week’s EYE ON NPI is no arbitrary pick, it’s Analog Devices’ AD8460 110 V High Voltage, 1 A High Current Arbitrary Waveform Generator with Integrated 14-Bit High Speed DAC!
It’s a bit of a mouthful, but that’s to be expected with a new IC with so much beefy goodness stuffed inside.
It’s like one of those massive hamburgers that you aren’t sure how to eat. And when we say beefy we mean BEEFY, because the output driver on this dac can handle +-55VDC and 1A sink or source. It’s like an all-in-one benchtop supply chip that doesn’t even need a separate driver stage.
Arbitary waveform generators – sometimes called function generators – are a common benchtop tool for the EE.
They tend to have a few basic waveforms they can generate for you: sine, square, triangle, saw and maybe impulse. They also tend to have a flat DC output, to act as a DC current supply as sink or source. They sit on the bench and when you’re ready to use, clip on some test leads and attach to your device or circuitry. Easy but they’re really heavy and designed for manual not automatic usage. If you’re designing test bed equipment, you may not want to have a huge loud machine on every QA spot. Also, you may want to have field analysis and repair and it’s not easy to carry, power and configure a bench generator on top of a tower, or in a machine room basement.
The Analog Devices’ AD8460 is a TQFP-sized solution to this big, heavy problem: it’s easy to integrate, easy to automate, and has lots of overlap with the benchtop devices.
Unlike low cost ‘arbitary waveform’ chips like the AD9833, the AD8460 has wide voltage and current specs: up to +-40VDC output swing and up to 1A sink/source. Note you’ll need to provide that power supply separately, which is no minor challenge.
There’s two ‘modes’ available: Analog Pattern Generation will let you cycle through up to 16 pre-set voltage levels in sequence, good for simple step or pulse tests.
Programming for the APG is done through SPI, it’s a vanilla 4-wire interface. Arbitrary Waveform Generation is what you would use if you need triangle or sine waves – but watch out because while you can program any waveform you desire, the values have to be shifted in through the 14-bit parallel inputs with a sync/latch pulse.
So your controller chip will need to be able to DMA out values at the fixed timing you need to hit your desired frequency without harmonics.
You may want to pick up a parallel-access SRAM chip to load big waveform sequences and then you can just have a square wave output from a basic timer peripheral to clock it out to the AD8460 maybe with the addition of a binary up-counter.
Either way you choose to run it, if you are planning on sinking or sourcing a significant amount of current – more than a few mA – you’ll need to think hard about thermal management because if you’re handling 100mA at 30V that’s 3W and a plain TQFP is not designed for that. The TQFP does have a big thermal pad on top. Use that to attach a chonky sink and fan as needed for your expected wattage needs. FYI, there is power / over-heat alarms available to configure on the chip in case you need to warn the user or dial down the voltage.
If you like the song we’re singing, you’re in luck because the Analog Devices’ AD8460 is in stock right now at DigiKey for immediate shipment!
There’s also an eval board is available, part EVAL-AD8460SDZ from DigiKey so you can jump in immediately to verifying that this chip will do the workload you require. Order today and you’ll be generating arbitrary waveforms by tomorrow afternoon!
See the Adafruit video below: