Can NI USB 6009 output constant source/sink current?

[Madhusudan]

Hi all,

I have a NI USB 6009 DAQ board. I need to charge/discharge a battery at constant current (<1mA) and simultaneously monitor its voltage. 

I was wondering if I can use USB 6009  to output constant source/sink current to charge/discharge the battery? I saw some threads which said 6009 cannot output constant current but other threads said we can use digital output to provide current, but it was not described how to do so.

Thanks.

[johnsold · Accepted solution]

All the outputs of the USB-6009 are voltage sources and all have fairly low current limits. There is no way to generate regulated current outputs directly from this device.

What I would do (and have done) is to build external current source/sink circuits with an op amp or a transistor and use a digital output from the USB-6009 to turn them on or off. If the current needs to be adjustable, use an op amp circuit which takes a voltage input from the analog output of the USB-6009 to set the current.  Use an analog input channel to monitor the battery voltage.

Lynn

[Madhusudan]

Thanks for the reply. I will try to make a voltage-to-current converter circuit.