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Supply System of CC2640

Vishal Algure
Prodigy 185 points
Other Parts Discussed in Thread: CC2640, TPS62740, TPS62730

Hi,

I have to use internal DC to DC switcher of CC2640 and also all IO's of CC2640 on 1V8 supply voltage. I am planning to implement this as datasheet suggest that use DCDC for lowest power consumption and 1.8V for external peripherals to consume less power.

Datasheet mention that VDDS is the highest potential in the system, so can I configure CC2640 in above configuration? 

Please find the below connections which I have done for same,

VDDS_DCDC= 3V

VDDS=VDDS2= 1.8V externally generated

VDDR=VDDR_RF= 1.8V output of internal dc to dc(connected to DCDC_SW through 10 uH inductor and 4.7 uF capacitor)  

 

Thanks and regards,

Vishal

  • 0
    TI__Mastermind 18780 points

    Hi,
    We have not tested different voltage levels for the different power domains yet, so the configuration you suggest is not supported at current time. For your system, I would recommend you to use external regulator mode (thus not the internal DCDC). With an effiecient external DCDC (like the TPS62740), the current consumption will approximately the same ( since that regulator does not switch to bypass in LPM due to the ability to maintaining high efficiency for uA loads, you will increase the sleep current by a little) .See for insant this thread on how to configure this set-up:
    e2e.ti.com/.../419186
    Note that if using the internal DCDC, the cap should be 10 uF. (4.7 uF were pre-RTM values. These were changed to 10 uF last year to be able to adjust the recharge cycle in standby and improve the sleep current. )

  • 0 in reply to CHS
    Prodigy 185 points

    Hi,

    Thanks for updated value for DCDC cap.

    Can you please let me know how much i will save power when I operate CC2640 over externally generated 1.8V using TPS62740(Core current and Radio TX/RX current).

    I found only current for VDDS=3V and using internal DCDC. Let me know if i missing it in datasheet or in any document.

    Thanks and regards,

    Vishal 

  • 0 in reply to Vishal Algure
    TI__Mastermind 18780 points

    Hi,

    I am working with an application report using CC2640 with the TPS62740, so stay tuned for more details. We have thus compared the efficiency of the internal DCDC and the TPS62740 and found it to be approximately the same (given that both output 1.8 V). So the current consumption will as said be approximately the same for the two set.up, expect that in low power modes (like standby) you will have to add the quiecent current of the TPS62740 (360 nA). Anohter alternative is also the TPS62730. The CC2640 datasheet included graphs showing the current consumption vs voltage supply, see p 22.