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Alternative to our precision amplifier obsolete device - OPA2604AU

Viktorija Cecil
Mastermind 18491 points
Other Parts Discussed in Thread: OPA1652, OPA1656, OPA2604, OPA1642

Team, 

Customer is looking for alternative to now obsolete OPA2604AU Precision amplifier. 

What would you recommend?

Thanks

Viktorija

  • 0
    TI__Guru* 93105 points

    Hi Viktorija,

    TI has newer, very high performance JFET input audio op amps such as the OPA1642, OPA1652 and OPA1656 that should perform well in many OPA2604 designs. The main differences with the newer options are their maximum supply voltage is +/-20 V (40V), vs +/-25 V (50 V) for the OPA2604. Additionally, the OPA2604 has some specifications specified with RL = 600 Ohms, or 1 kilohm, while the OPA1642, OPA1652 and OPA1656 are specified with a RL = 2 kilohm, or 10 kilohm. Note however, the output current capabilities of the op amp's are similar to, or even higher (OPA1656) than, the OPA2604.

    http://www.ti.com/product/OPA1642

    http://www.ti.com/product/OPA1652

    http://www.ti.com/product/OPA1656

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    TI__Guru* 93105 points

    Hi Viktorija,

    A small correction - The OPA1652 and OPA1656 are HV CMOS, not JFET input op amps. The OPA1642 is indeed JFET input as stated earlier.

    CMOS op amps exhibit a higher 1/f knee frequency compared to a similarly performing JFET input op amps. If the 1/f noise at a low frequency such as 0.1 Hz, 1 Hz, 10 Hz, etc. is especially important in an application, then the comparable JFET input op amp will exhibit lower 1/f noise at very low frequencies. In which case, the OPA1642 would be the better choice.

    However, when you compare the 1 kHz input voltage spectral noise density of the OPA1652 which is typically 4.5 nV/rtHz, with 4 nV/rtHz for the OPA1656 and 5.1 nV/rtHz for the OPA1642, the broadband noise is very comparable and low for all the op amps. That may actually be the more important measure of noise in the audio application.

    Regards, Thomas

    Precision Amplifiers Applications Engineering