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LT6105IMS8#PBF equivalent or better

Norman Oliva
Prodigy 210 points
Other Parts Discussed in Thread: INA168, INA138, INA240, INA180, INA281, INA290, INA282

Hello, I'm looking for an equivalent TI part for LT6105IMS8#PBF, I'm basically looking for a pin to pin compatible and with better specs than LT6105IMS8#PBF.

Thanks,

Norman

  • 0
    TI__Mastermind 18780 points

    Norman,

    As this is a current output type of current sensor, we only have two options for replacement here, the INA138 and the INA168.

    Analyzing these devices under a microscope, it appears they are similar, but not functionally equivalent (the INA138 boasts better specs in a lot of areas, including BW, Iq, CMRR, PSRR, etc. The major difference I spotted is that LT6105 is low side capable. INA138 is not). Unfortunately neither the INA138 or 168 come in an MSOP or DFN package, so there is not a p2p replacement. 

  • 0 in reply to Carolus Andrews
    Prodigy 210 points

    Hi Carolus,

    Is there any similar device that is low side capable? Is my assumption correct that all INA series are only good for  for high-side sensing application? Our current application for that LT device is actually for low-side sensing and we are looking for a much better replacement, cost is not issue so far.

    Kindly advise.

    Thanks,

    Norman

  • 0 in reply to Norman Oliva
    TI__Mastermind 18780 points

    Norman,

    This depends on how close you need the device to be.

    We have several current amplifiers that are low side capable, but these devices output a voltage signal rather than a current signal. The LT6105 is a current output device, of which INA138 and INA168 are our only offerings. While the transform is pretty straightforward (picking up the external gain setting resistor), the loop is now closed internal to the device and laser trimmed, so they come with a preset gain that is extremely accurate (normally 1% or less gain error at worst case condition. Typical can be <.2%).

    If you can look at similar, non p2p devices, this opens up the conversation quite a bit. The first one I would direct you to is INA281. This device is effectively the similar structure you are examining now with a buffered voltage signal. However, this comes in a SOT-23-5 package, and is not available in MSOP-8 or DFN. You could also look at INA180 if you need a cost optimized solution, or INA240 if you need true performance here. 

  • 0 in reply to Carolus Andrews
    Prodigy 210 points

    Thanks Carolus, I tried to search before posting questions in E2E and found INAx290, not sure if this can also be used for low-side sensing or if there is an equivalent low side sensing with similar CMRR specs as INAx290.

    Thanks,

    Norman

  • +1 in reply to Norman Oliva
    TI__Mastermind 18780 points

    Norman,

    The INA290 is not low side capable.

    The way you can easily determine whether a device is or not is by examining the common mode voltage range of the device in question. The common mode voltage of an amplifier is the voltage of each input pin added together and then divided by two. For a low side configuration, the IN- pin sits typically sits on GND, so it is 0V, and the IN+ pin is only a few millivolts above this (the sense voltage), so for all intents and purposes, the common mode voltage of a low side application is approximately 0V. For the device to be low side capable, 0V should fall in the common mode range of the device. As you can see, the minimum Vcm that INA290 allows is 2.7V, and therefore won't work for low side applications. 

    Some of our higher CMRR devices that are low side capable are the INA240 and the INA282 family. 

  • +1 in reply to Carolus Andrews
    Prodigy 210 points

    Thank you, I think I'm good now.