6 Replies Latest reply on Jul 20, 2019 5:40 AM by PaSv_1652016

    Best power supply design  for adc

    PaSv_1652016

      Hello COMMUNITY 8))

      please  give me recommendations about suply

       

      i have :

      Psoc 5lp for ~16-18bit ADC and postprocessing

      full Isolated dif amp (TI amc1301) for measure current  shunt.

      Shunt located in heavy EMI from random ultra HV sparks.

      for power supply device i  want use  1s Lipo 2x18650 3500mah

      device shilded in metall  box

       

      i need maximum ADC  perfomance  for my situation , and long battery life.

       

      in this case i have some questions:

       

       

      1. can i supply PSOC (Vddd= 3.3-4.2v) direct from LIPO without LDO, or best way  use buck/boost regulator for full lipo dicharge to 3.0 V , and stabil 3.3 main voltage?

       

      2. how i understand, for accurate ADC measurement i need external Vref.
      in this case  i can use dual Vref ic TI REF2033 (1.65V20mA + 3.3V20mA, 6 ppm/°C ,  Accuracy: ±0.05% ).

      REF2033 out1  Vref 3.3 ->  to PSOC Vdda + amc1301 Vdd2
      REF2033 out2 Vref 1.65 -> to PSOC Vref

      or you can tell me a more optimal solution ?

       

      3. isolated DCDC for isolated amp parts + 3.3 LDO to amc1301 Vdd1 

      ADUM6000 or any other 1:1 isolated DCDC

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

       

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        • 1. Re: Best power supply design  for adc
          EmHo_296241

          Hi,

           

          For the first question, buck/boost regulator should improve your battery life.

          • 2. Re: Best power supply design  for adc
            PaSv_1652016

            "For the first question, buck/boost regulator should improve your battery life."

            But buck/boost  will add noise ...

            may be  3.3V LDO beter ...

            • 3. Re: Best power supply design  for adc
              BoTa_264741

              PaSv,

              "16-18bit ADC" and "random ultra HV sparks" do not come along. Data collected during the sparks, has to be discarded.

               

              PSoC5 has internal 1.024V reference, which is sufficient for 16-18-bit DelSig_ADC measurements. I don't believe that any improvement can be made using external voltage reference, particularly in noisy EMI environment.

               

              Simple data acquisition by PSoC5 will draw about 30mA,  a pair of 18650 3500mAH each will run the system for 10 days continuously. I would use batteries directly, without any DC-DC converter. Voltage variation 4.2 down to 3.3V should not be an issue.

              /odissey1

              • 4. Re: Best power supply design  for adc
                PaSv_1652016

                " do not come along. Data collected during the sparks, has to be discarded." for the most accurate measurement, I plan to make a double shielding box + isolated shunt ground ( isolated shunt amplifier TI amc1301  ) ....and yes big currents, I will reject with post-processing

                 

                 

                "PSoC5 has internal 1.024V reference, which is sufficient for 16-18-bit DelSig_ADC measurements. I don't believe that any improvement can be made using external voltage reference, particularly in noisy EMI environment."
                hm .. sounds good.


                "Simple data acquisition by PSoC5 will draw about 30mA,  a pair of 18650 3500mAH each will run the system for 10 days continuously. I would use batteries directly, without any DC-DC converter. Voltage variation 4.2 down to 3.3V should not be an issue."

                 

                ok in this case my task is a little easier:

                 

                                                                    [~50ma leds fiber optic TX]--{to PSOC GPIO}

                                                                    |

                [2x 18650 DC ] ------[3.3V LDO]---------------[ISOLATION 3.3V DCDC]----[3.3VLDO]-----|
                                        |                                                                                                                     |

                                        |                                                                                                                     |                      (HV+)

                                        |                        (6.9mA)                                                        (6.9mA)          |                       |
                                        |-------------------[ AMC1301 VDD2 |ISOLATION BARIER | AMC1301  VDD1] =======||  {SHUNT}
                                        |                               |                                                                                                             |

                                        |                               |                                                                                                             (HV-)

                                        [PSOC 5LP ADC] ---|(ADC in)

                • 5. Re: Best power supply design  for adc

                  Power consumption is the most important when you think of design any system. ADC is used for the conversion of analog to digital. A key component of the power supply is isolating the switching and circuits always required a separate power supply. If we do not use a separate power supply so sometimes we face short-circuits issues. There I have seen a huge short circuit due to combining power supply.

                  • 6. Re: Best power supply design  for adc
                    PaSv_1652016

                    "A key component of the power supply is isolating the switching and circuits always required a separate power supply."

                    Yes, and for separate  i want use 3.3V to 3.3V DCDC Isolation module

                    for example https://power.murata.com/cme0303s3c.html

                    (Murata cme0303s3c )