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Replace LM334 with LM234-3

Vaibhav Pawar63
Intellectual 395 points
Other Parts Discussed in Thread: LM334

We are using LM334 as a current source in one of bio-medical product. LM334 is followed by 4 stages of OP-AMP, ADC and uC. ( Input to OP-AMP is in uV range and current from LM334 is 3.3uA)

I have gone through LM334 datasheets and found that LM234-3 has better current and temp error drift, so better compare to LM334.

So We are planning to replace LM334 with LM234-3 in our application. Can I do so? Will it be good option if we want to improve noise in instrument.

Thank you in advance.

  • 0
    Genius 3295 points

    Hi Vaibhav,

    Are you implementing the "tempco" correction circuit? Do you have a schematic for reference on how the device is implemented? Perhaps there are other noise sources contributing to the overall signal.

    @TI: Being slightly pedantic; please pass along to the "datasheet" people that when talking about temperature, Kelvin is an absolute. No "degree" sign (-°) should be used with "K" as it is with "°C" or "°F".

    Mike T.

  • 0 in reply to Mike Tripoli
    Intellectual 395 points

    Sch. for ref

    Application is blood cell counter where WBC,RBC measurement is done with instrument. RBC signal in above schematic is coming from Liquid chamber where blood sample is kept and 2 electrodes are attached to two ends of liquid chamber. Constant current is passed through electrodes and using impedance measurement method, measurement is done. ADC AD7821 is used for signal conversion.


    Please suggest any current source with higher noise immunity and with same footprint package (LM334)

    Thanks