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OPA192, Precision, Rail-to-Rail Input/Output Operational Amplifier

Discussion in 'Datasheets, Manuals or Parts' started by spec, Oct 29, 2015.

  1. spec

    spec Well-Known Member Most Helpful Member

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    AS THE CONTENT OF THIS POST HAS BEEN CONVERTED INTO AND ARTICLE WOULD ADMIM/MODS PLEASE DELETE- THANKS


    There have been many game-changers in the history of operational amplifiers, µA709, µA741 for example, and I'm wondering if the Texas Instruments OPA192 is the latest. I've been itching to try one out since the data sheet was released about 18 months ago, but even though the devices are now freely available, I don't have a workshop. Does anyone have any experience of them? I'd be particularly interested to know if they are generally well-behaved and I'd also like to know, especially from any HiFi buffs, if they sound any good as audio amplifiers.

    Going by the datasheet, this operational amplifier is remarkable, in fact, practically ideal and opens up a whole range of circuit design possibilities. If it is well-behaved it would also help students, because many of the shortcomings of the common 741 types, tend to cloud the issue when an actual circuit is built. Surprisingly, in spite of the specification, the OPA192 isn't too expensive either: Mouser has them at a one-of price of £2.20, and this will probably drop when the OPAx92 family has been on the market a bit longer. http://uk.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=152100822

    Here are the main parameters from the datasheet* that make this operational amplifier so exceptional, especially the extremely low input offset voltage and current. Before this you might have got some of these advanced features in one chip, but what makes this chip unique is that it has them all:

    • Wide Supply Rails: ±2.25 V to ±18 V, +4.5 V to +36 V
    • High output current (±65 mA)
    • Rail-to-Rail Input and Output Voltage
    • Low Quiescent Current: 1 mA per Amplifier
    • Differential Input Voltage Range to Supply Rails
    • Wide Bandwidth: 10 MHz Gain Bandwidth Product
    • High Slew Rate: 20 V/μs
    • High Capacitive Load Drive Capability: 1 nF
    • Unity Gain Stable
    • Low Input Offset Voltage: ±5 μV
    • Low input Offset Voltage Drift: ±0.2 μV/°C
    • Low Input Bias Current: ±5 pA
    • Available in single (OPA192), dual (OPA292), and quad (OPA492) versions

    One slight downside is that the OPAx92 is only available in surface mount, but there's always the option of mounting the surface mount package on a DIL converter for experimenting.

    Also, the rail-to-rail input relies on two complimentary differential amplifiers in parallel at the input. The bottom differential amplifier handles all input signals from the negative supply rail to approximately 2.5V below the positive supply rail, where the top differential amplifier takes over. This gives a slight discontinuity in the transfer function at the change-over point which probably wouldn't be significant at DC and low frequencies but would be an area to avoid for higher frequencies and HiFi audio.

    * OPAx92 family datasheet: http://www.ti.com/lit/ds/symlink/opa192.pdf
     
    Last edited: Feb 25, 2016
  2. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    AS long as you don't use if for a low noise preamp, it looks like a great CMOS Op Amp
    Low Noise: 5.5nV/√Hz at 1kHz
     
  3. spec

    spec Well-Known Member Most Helpful Member

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    Yes, the noise is a bit high by modern standards, similar to the venerable NE5534, so the OPA192 probably wouldn't be ideal for a moving coil pickup cartridge or mic. The very low input current may help though in a circuit.
     
    Last edited: Oct 29, 2015

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