USB Digital to Analog Converters with Timed Outputs
Recently, I had what seemed like a simple task: select a DAC (digital to analog converter).Â There are hundreds of models, so it should be easy, especially since most of my requirements were not demanding (1 channel, 12-bit or better, 1KHz output rate, 0-10V, low jitter output, and reasonable cost, hopefully <$500).Â Â Even my low jitter requirement wasn’t demanding; I’d be happy with 100 microseconds of jitter; basically, any unit with a decent FIFO buffer and a hardware timed DAC update should work.
But finding candidates was a lot of work.Â Early on, I concentrated on USB DAC models, because they have sufficient speed, are self-powered, tend to be reasonably priced, and don’t need a PCI or PCIe slot.
I’ve used Measurement Computing before, so they were one of my first stops.Â It was really hard to find exactly which models have FIFO buffers and hardware paced outputs.Â I had to do a lot of searching — and reading the full manuals.
The cheapest Measurement Computing model that met my requirements is the USB-1208HS-2AO, which is overkill ($599, high speed USB 2.0, 2 12-bit analog outputs at 1MHz, DAC has 4K FIFO buffer).Â As far as I can tell, nothing cheaper has a FIFO buffer for the DAC.
Data Translation wasn’t much better; I had to dig through the detailed specs PDF to discover that the DT9812-10V meets my requirements, and has a 2K FIFO buffer.Â It’s $375; DIN Rail mounting is an extra $60.
The final contestant is the Accesio USB-DA-12-8A, which has a 128K samples buffer.Â It’s $525; DIN Rail mounting is an extra $19.
For my application, the Accesio looks the best fit; it more than meets all my requirements, I like the large buffer, andI like the DIN Rail mounting option.
Update Aug 2014:I was look at USB DAQ devices again, and I’m happy to say the situation is much better now.Â For example, MCC’s USB-231 for $249 has 2 16-bit DACs that support simultaneous hardware-paced updates at up to 5KHz.Â It also features 8 SE (or 4 DE)Â 16-bit analog input channels with 50KHz max sampling rate, 8 digital I/O, and 1 32-bit counter / timer.