Original question:
Hi，
I have a related question for operating current. PGA308 working in ONEWRIE mode,but it's working current of the chip about 40mA, Sensor and LDO consume 3mA.
VS= +5V ,VREF=2.5V, Wheatstone sensor with the same 2.5V supply. Calibration and communication ok.
5V Supply and communication from USB DAQ board.
How to reduce power consumption?
Thank you and Regards
Hi ZhenGuo,
Where did you find the working current of PGA308 is about 40mA? Are you running the application with battery powered energy?
How to reduce power consumption?
1. If you reduce the Input Voltage, say 6V, the LDO's power dissipation = Iout *(6-5V) = I out in mW. The input voltage range in this part is from 2.7V to 5.5V, see attached image. Please check out the user guide per your application.
2. The pull-up resistor for 1W application can be high. I do not know how many modules you are going to connect on the 1W bus. If the number of devices are not many, you may use weaker pull up resistor. The pull-up current source range is from 15nA to 45nA. Say you want the pull-up current at 20nA. The Vdd is 3.3V, thus your pull-up resistor is 3.3V/20nA = 165kOhm, as an example.
3. Also, lower transmission data speed will consume less power.
4. If you are able to use lower excitation voltage and high Wheatstone bridge resistors, since the input impedance both both differential or common mode of PGA308 are very high. Pay attention to the linear input voltage range, which is from 0.2V to Vs-1.4V, see p.3 of the datasheet.
5. Implement the Dout/Vlamp feature in the IC. Use OTP memory, if you can.
6. Limiting power amplifier's output current and maximize the output voltage swing. The output amplifier's power consumption is Iout*DeltaV-swing.
http://www.ti.com/lit/ug/sbou069b/sbou069b.pdf
If you have any other questions, please let us know.
Best,
Raymond
