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# CC2540/2541 Inbuilt Regulator TPS62730DRY

Hsa S
Expert 2570 points
Other Parts Discussed in Thread: CC2540, ASH, TPS62730, TPS62740, CC2541Dear TI, I want to know, whether CC2540/2541 has inbuilt voltage regualtor (3.0v to 2.1v) or not? Should I need to use external volatge regualtor for set ADC reference? Please suggest~ Regards, /Ash
  • 0
    Guru 735685 points
    You can use internal VDD3 which is 1.15V as ADC reference and don't need external voltage regulator to set ADC reference.
  • 0 in reply to YiKai Chen
    Expert 2570 points
    Dear Mr Chen,Thanks for your prompt reply~
    Is this defined as VDD/3 Or VDD3 ? and as I am using the battery source for my device (3.0V), in this case the ADC ref voltage would be 1.0V, is it right?
    Please guide~Thanks n Regards/Ash
  • 0 in reply to Hsa S
    Guru 735685 points
    It is defined as VDD/3 but actually it is 1.15V not 1V.
  • 0 in reply to YiKai Chen
    Expert 2570 points
    Ok Mr Chen, I understood.Thanks for the help.Regards, /Ash
  • 0 in reply to Hsa S
    Guru 735685 points
    Hi Ash,
    You are welcome! Please help to press the verify button on my replies if it helps you. In this way, we can benefit others with the same issue.
  • 0 in reply to YiKai Chen
    Expert 2570 points
    Yeah sure, I did it. I will try to use the Internal reference as ADC-ref and test the device. will update you after the test.
    Thanks.
  • 0
    TI__Intellectual 1915 points
    Hi,

    You are referring to the TPS62730 on the title, can you tell us more how are you using it? if the aim is power saving I suggest to you to check the TPS62740, it is an improved version with low quiescent current so no need to switch permanently between bypass and DCDC mode.

    Regards,
    Amjad
  • 0 in reply to Amjad EL HILALI
    Expert 2570 points
    Dear Amjad,
    we are using it for getting the fixed ADC reference voltage and then using a voltage divider (hardware circuitry), we r going to measure the correct BATT_MON value. But as CC2540/CC2541 has in built internal reference for ADC then we will use that.
    Can we use TPS62730 for more purposes ?Please suggest~ThanksRegards,/Ash
  • 0 in reply to Hsa S
    TI__Intellectual 1915 points
    Hi Ash,

    In fact I think it's a better idea to use internal ADC reference rather than using a DCDC to generate a fixed reference voltage...

    So concerning the TPS62730 or even better the TPS62740, they are very good DCDC converters for light load applications, they help extend batteries life by having very high efficiency even for very light load (1-10uA).

    So if you tell us more about your application (used power supply or type of battery, what load do you need...) I can give you more support.

    Regards,
    Amjad
  • 0 in reply to Amjad EL HILALI
    Expert 2570 points
    Dear Mr Amjad,Thanks for your kind response.
    well, I understood so far is, we can use the voltage regulator for two purposes....1) If we want we can get the ADC reference from it (normally use internal reference). 2) Additional power saving by using TPS62730/40. Is this correct?
    Also, before using the voltage regulator TPS62730/40 in my hardware, I want to try a dummy experiment to check the power saving operation. How can I do that? Pelase suggest.
    Thanks n Regards,/Ash
  • 0 in reply to Hsa S
    TI__Intellectual 1915 points

    Hi Ash,

    1) Well I wouldn't recommend using a DCDC buck converter to provide an ADC reference as the output voltage has some ripple due to the switching topology of the converter. It's recommended in order to get an ADC reference to use either external voltage references or use CC254x internal reference.

    2) Concerning the power saving I would recommend to first supply your CC254x directly and measure the output current ( you can use a variable voltage supply and test different voltage from 2.1 to 3.4V for example), and then use the TPS62740 with a 2.1V output and vary your input voltage. You will see that the drawn current is decreased significantly using the buck converter. comparing to direct supply.

    Also note that a battery's life is reduced when using higher current peaks even is the same amount of power is used.

    If my post answers your question, please click on "Verify Answer" button to benefit others who have the same issue.

    Amjad

     

  • 0 in reply to Amjad EL HILALI
    Expert 2570 points
    Dear Amjad,Thanks for your well explanation~
    I got the point and try to do the experiment.Thanks n Regards,/Ash
  • 0 in reply to Hsa S
    Expert 2570 points
    Dear Amjad,This is regarding the discussion I had with you last time.
    well after checking the DS of both the regulators (TPS*****30 and TPS****40), Input voltage range is different, o/p current is diferent and output volatge is fixed in case of TPS****30 (2.1V), TPS****40 (1.8~3.3V). Could you please emphasise, which one is better for power saving in all respect ?
    Thanks n regards,/Ash
  • 0 in reply to Hsa S
    TI__Intellectual 1915 points
    Hi Ash,

    In general way the TPS62740 is much better, as it's a newer design, more flexible, with wider input range and with outstanding low quiescent current.

    But it also depends on your needs. You should know that the TPS62740 is a little bit more expensive than the xxxx30, and if your input voltage if no more than 3.8V and total application average current is more than 50uA I would rather go for the cheaper the TPS62730.

    Regards,
    Amjad
  • 0 in reply to Amjad EL HILALI
    Expert 2570 points
    Dear Amjad,Thanks for your reply~
    well, I found thar at very low output current, the efficienncy of TPS*****30 is around 60%, which is very low for application.
    Also, as I want to use the internal reference for ADC, I selected [#define HAL_ADC_REF_VOLT HAL_ADC_REF_124V]. Is that Ok?
    I am curious to know that, as I am using 3.0 volt coin cell battery and internal reference is VDD/3 which makes it 1.0v, then why it is mentioned the it would be 1.15 volt. Or if it is 1.15 volts then I have to use it as [#define HAL_ADC_REF_VOLT HAL_ADC_REF_115V].
    I am hoping to get clear with this doubt.Thanks n regards,/Ash