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INA223AIDSKT

Namith HL
Intellectual 570 points
Other Parts Discussed in Thread: INA223, INA225, INA226, INA233

Hello,

I have selected INA223 for Voltage and monitoring for stereo amplifier output .

we have designed by considering our amplifier output supply as  24V, But now we have to give a provision for 30V Common mode voltage also.since INA223 can support upto 26V.

so now we have included divider network after current sensed output from the amplifier ,

we adjusted divider network 30v should give a secondary voltage of 24V.

Please have a look at my schematic and kindly  suggest me this option feasibility.

I have limited time to finalize my design.

Iam awaiting for your reply as earliset

INA223 Current sensing feasibility.pdf

  • 0
    Guru 140200 points

    Hi Namith,

    simulation shows that the imbalance of your voltage divider resistances of even only 0.1% is enough to totally destroy the performance of chip!

    Input stage of INA223 is extremely symmetrically fabricated in order to suppress any common mode voltage to a very high degree, high enough to be able to handle the very little differential signals in the presence of high common mode voltages. The imbalance of your voltage divider destroys the extreme high input symmetry of INA223.

    Kai

  • 0 in reply to kai klaas69
    TI__Mastermind 26660 points

    Hey Namith,

    Another way to look at the effects of the voltage divider on the inputs is input offset current, which is the difference between IB+ and IB-. We don't have this specified, but if IB+ is 25uA and IB- is 24uA, then this would create a 18mV offset immediately. Meaning if the voltage drop across the shunt resistor is 48mV, then the voltage actually sensed by INA223 would be 30mV. This would not be a robust design. Additionally, the input differential impedance is 2.5kOhms. Adding input resistors comparable with this value creates a significant voltage divider and this would further reduce the voltage actually being sensed by INA223.
     
    You might be better off using the programmable-gain INA225 which can support up to 36V common-mode, has better BW, and is cheaper than the INA223.

    Sincerely,
    Peter Iliya
    Current Sensing Applications

  • 0 in reply to Peter Iliya
    Intellectual 570 points

    Hello thank you for reply,

    But we have to monitor both voltage and current monitoring (power), so we had chosen that,

    Now we already running out of time. 

    Please suggest IC that can measure both Voltage and current monitoring (power) similar to INA223

    So you have suggested INA225 will that  can measure both Voltage and current?

    Also INA223 and INA225 frequency and gain graph also suited to our design ,but our concern is as per datasheet INA225 only measure current.

    Can we measure both voltage and current?

    Please suggest IC that can measure both voltage and current ,upto 30V-36V common node voltage

    Regards,

    Namith

  • 0 in reply to Namith HL
    Guru 140200 points

    Hi Namith,

    the INA225 can only provide a current measurement.

    Kai

  • 0 in reply to Namith HL
    TI__Mastermind 26660 points
    Hello Namith,

    I understand your concern. What is the bandwidth you need? The INA223 is the only current sense amplifier (CSA) that contains a power monitor AND an analog output pin. We have power monitors, but they report the shunt voltage, current, and power over I2C or SMBUS. These devices usually have an internal 500kHz delta-sigma ADC with conversion times as low as 140 us. They can support 36V common-mode voltage and can automatically adjust their gain. Examples of these devices are INA226 or INA233 You can view the other power monitors here:
    www.ti.com/.../products.html

    Regards,
    Peter Iliya
    Current Sensing Applications