CCS/PGA900: PGA900 DAC

chennangan

Part Number: PGA900

Tool/software: Code Composer Studio

Hello ；

section 1:

Voltage measured between GND pin in the PGA900 and negative terminal of
the controller. This includes the internal 40-Ω resistor and an external 10-Ω
resistor, VDD = 15 V. The DAC codes used were 0x880 and 0x2760 for 4 and
20 mA respectively.(PGA900 datasheet SLDS258 Page )
section 2:
The DAC codes used were 0x830 and 0x28EB for 4 and
20 mA respectively.(PGA900 as 4 to 20 mA C urrent loop Transmitter SLDA030)

So what is more correct?

over 5 years ago

0 Scott Cummins over 5 years ago

TI__Mastermind 31655 points

Hello Chennangan,

The plot from the "PGA900 as 4 to 20 mA Current loop Transmitter SLDA030" application note is a direct result of Equation 1 from that application note. It is an ideal graph that does not take into account DAC offset or gain error.

The application curve from the datasheet shows real measured data from a specific PGA900 device. The offset and gain error of that particular device caused it to deviate somewhat from the ideal values described in the application note. The difference between the two values is within the 3.5% FSO error of the DAC in current operating mode. This error can be compensated for when doing the device calibration procedure.

Regards,

0 chennangan over 5 years ago in reply to Scott Cummins

Intellectual 750 points

Hello Scott:

I try different PGA900 chips on the same PGA900EVM . The same DAC_REG0 output can case different current output in current operating mode .

Does It means that I should do all of devices calibration procedure

0 Scott Cummins over 5 years ago in reply to chennangan

TI__Mastermind 31655 points

Hello Chennangan,

Yes, for the best accuracy and consistency among sensors you will need to perform a calibration for each one.

Regards,

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CCS/PGA900: PGA900 DAC