Looking for DAC - medical TENS application

Vladimir,

I would suggest looking at precision DACs which may have a more appropriate digital interface to the MSP430. The DACs in our highspeed product line require generatlly a parallel CMOS interface or an LVDS interface. Also most of our DACs have a min sampling rate of 10Msps or higher. Your application may be better suited with a serial interface DAC.

Ken

Hi Vladimir,

I am from the precision DAC group. If I understand correctly you are trying to generate square current pulses. We have an integrated solution that might be able to suit your needs. Take a look at the DAC7750. It is a serial input DAC with a typical current settling time of 10 μs. Will that settling time be sufficient in your application?

Another option is to build the current output externally. You would need to use one of our DACs fast settling precision DACs (~0.5s) and choose a fast settling output transistor to do the V-to-I conversion.

Please let me know if you have any questions.

Vladimir Vidiborschii said:

During current settling time, do the output has some current glitch or not?

There is a small glitch that occurs when writing a code as shown on Figure 47 of the DAC7750 datasheet.

The Iout pin, also displays some glitches when the device is powering on and when the Iout output is enabled as show my Figures 45 & 46 respectively.

Vladimir Vidiborschii said:

What is total setting time from power ON to get the required Iout current level?

The device is ready to communicate as soon as AVDD reaches 10 V. After this point, you would need to enable the reference, and then enable Iout. We don't specify a specific power-on delay.

Vladimir Vidiborschii said:

What is total current consumption of DAC7750 itself with powering with 12V and output enable to give 10mA ?

DIDD will be either 0 or 1 mA, depending if DVDD is generated internally or externally respectively.

AIDD will be either 4 or 3 mA, depending if DVDD is generated internally or externally respectively. (i.e. AIDD + DVDD will always be 4 mA)

Total current = AIDD + DIDD + Current_output

This means in your case, it will be 14 mA.

Vladimir Vidiborschii said:

In our application the prototype will be powered by a wireless charged super-capacitor, so we also need to get lowest power consumption of circuitry itself....

It seems that low-power is critical for your application. In this case, I don't think the DAC7750 will be a great candidate since it has a 4 mA operating current. The only option would be to build a discrete current output, I would suggest using the DAC7311 due to its low power power consumption.