Fiding "Voltage to Current" Converter

[thuaniam]

Hi all friends,

I need to buy linear Voltage to Ampe converter. Could you please let me know some product options?

The input is variable in range of 0 to 10V (or +/-10V) or less.The output is proportional to the input. The output range can be about 0-2A (or +/-2A) or larger.

Thank in advance.
Van

 

[(*steve*)]

What is the relationship between control voltage and current? is it I_out = (V_control / 5)?

What is the load? (does it have any interesting behaviour (negative resistance, high inductance, high capacitance, dynamic variability, etc)?

What is the source of power for the controlled current (Voltage, max current, etc)?

What are you trying to do?

 

[thuaniam]

What is the relationship between control voltage and current? is it I_out = (V_control / 5)?

What is the load? (does it have any interesting behaviour (negative resistance, high inductance, high capacitance, dynamic variability, etc)?

What is the source of power for the controlled current (Voltage, max current, etc)?

What are you trying to do?

Hi,

Sorry that I did not state about the load and other requirement.

I use an analog output signal of a realtime controller to control a MR damper.

My program will send analog signal in range 0 - 10V (or any other range within the maximum from -10V to 10V, depending on the actual input range of the converter), the converter will convert voltage (0-10V) to current (0-2A) for control of the MR damper. Let say the gain = 2A/10V for the given values.

An exact value of relationship between output and input is not important because it can be accounted in my program which runs in a the controller. The input range of the converter maybe different with 0-10V (for example, 0-1V or event bipolar such as +/-1V, +/-10V) because I can program the output of the controller in range from -10 to +10V. The output range of the converter should cover the range 0 to 2A in order to fully control the MR damper. If the current range of the converter is larger than 2A, I can program a suitable control signal in order to limit in range 0 to 2A.

The control signal is varying and the frequency range is DC to 10 Hz.

The load is a coil of the MR damper. The resistance of the coil (approx. 5 Ohm) is the major of imperdance of the MR damper.

The power supply for the converter should be DC. Since the voltage on the load varies from 0V to about 10 V (5Ohm x 2A = 10V), the power supply would be about at least 12V or more. Depending on the actual converter, I will arrange a suitable power supply.

I hope someone can help to find a suitable product for my application.

Thank you.

Van

 

[(*steve*)]

I'm not sure you'll find a suitable device off the shelf, however it's not too hard to make one.

Do you have any skills/experience in building electronic circuits?

 

[thuaniam]

I'm not sure you'll find a suitable device off the shelf, however it's not too hard to make one.

Do you have any skills/experience in building electronic circuits?

I can make it. However, I am looking first to buy a commercial product to save my time.

Thank you.
Van

 

[BobK]

This looks useful:

http://www.linear.com/solutions/4475

Bob

 

[thuaniam]

This looks useful:

http://www.linear.com/solutions/4475

Bob

Thank to Bob.

It is interestring, from your comment, I found that the LT3086 has many functions. However the current control function using TRACK voltage maybe not precise for control (in terms of linearity and accuracy).

Seeing the diagram of LT3086: the output current of the TRACK OPAMP and the output voltage of the ERROR OPAMP are proportionally linear to the voltage at TRACK pin. The output current (as limited current on the QPOWER transitor) is likely proportional to these control signals but this mechanism is opened loop and there is no feedback mechanism to ensure the relationship is highly linear.

I will make a linear conversion using OPAMP and transistor with a good feedback mechanism. I will placed zero offset and gain adjustments.

Thank you again for your helps.

Van