Monday, July 4, 2011

Why hasn't Microchip fabricated IAs?

I only use op amps which are single supply and I practically don't use any other op amp except those by Microchip because they're cheap, easy to obtain, and a good number of them have rail to rail I/O. Well, right now I need a single-supply instrumentation amplifier to clean up possible common mode noise from a sensor that'll be located many meters away from the control board. No amplification is necessary or desired. Unfortunately the only IA I have on hand is the INA126 which needs a bipolar supply (else output won't go all the way to ground) and has a minimum gain of 5.

Because the input signal is low impedance I could just use a differential amplifier. I can cobble one up using, say, a MCP6021, but that would entail the hassle of either getting precision resistors or manually matching four. It also increases the parts count. So that got me wondering why Microchip--given their wide range of op amps--hasn't taken the next step and developed instrumentation and difference amplifiers. Do they lack the capability to make these high precision components? Is the demand for these items too small? Is that market cornered by Analog Devices and Texas Instruments?

It's still on my wishlist and hopefully Microchip does get around to fabricating IAs in the near future. I'm sure they'd be more affordable than, say, the AD623.

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