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High Current Amplifier

Other Parts Discussed in Thread: OPA549, OPA548

Hello Everyone!

Our Application is to Control the speed of a DC Motor, without using PWM. 

12V DC Motor that takes 2-3A current at full load.

The Input Volatge to the Amplifier will be in the range of 0-5V and it should probably be able to drive the said motor.

Can you suggest an Amplifier which will meet our specifications? I have checked out all the available OPAMPs in the High Current Amplifier Section! No, Amplifier gives an output voltage in the range of 9-15V!

Thanks!!

  • Dhruvin,

    Please take a look at OPA549 shown below.  Its power supply voltage range is from 8V to 60V and the output can swing around 3V from either rail under 2A load.  This means for 15V output voltage you require, you will need at least 18V supply - no linear op amp can have output swinging all the way to its rail since this would require the output transistor Vds=0V (this could only happen when there is no current flowing in output stage transistors).

     

  • Hi Dhruvin,

    Consider the OPA548 high-voltage, high-current operational amplifier. It is often used in analog motor drive applications. It is rated for a continuous 3 Amp output current, with a 5 Amp peak output rating. The OPA548 is usable with a single +8 V to +60 V supply, or dual polarity supplies of +/-4 V to +/-30 V. It shouldn't have any problem delivering a 9 to 15 V output level providing a supply with sufficient headroom (V+) - Vo is used. The common mode input voltage range extends to the negative supply rail so 0 V to 5 V is a viable input voltage range when using a single supply. It has an adjustable output current limit and internal thermal shutdown which can help protect the amplifier.

    You can find the OPA548 data sheet here:

    http://www.ti.com/lit/ds/symlink/opa548.pdf

    Data sheet figure 14 shows a typical motor drive circuit. Study the data sheet carefully and let us know if you have any questions.

    Regards, Thomas

    PA - Linear Applications Engineering

  • Hey Thomas

    Thanks! It cleared my doubts! I'll be going forward with OPA548. 

    Thanks a lot!

  • Hi Marek! 

    Thanks for the help. Mr. Thomas suggested another IC OPA548. I compared it to OPA549 and found that my requirements are met by OPA548 and also, its cheaper!

    Thanks once again!