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CC2340R5: Power Draw Comparison, DC-DC to GLDO

Cole Mehring
Prodigy 30 points
Part Number: CC2340R5

Hello,

I am comparing power states on the CC2340R5 between the DC-DC converter and GDLO. DCDC source voltage would be 3.0V, GLDO source voltage would be 1.8V. This is the best table I can generate from the datasheet:

CC2340R5 DCDC Voltage 3   CC2340R5 GLDO Voltage 1.8  
Mode Current (uA)

Power (uW)

   Mode Current (uA)

Power (uW)

   Mode % difference CC2340R5 GLDO to DCDC
Standby LFOSC 0.71 2.13   Standby LFOSC 1.1 1.98   Standby LFOSC -8%
Transmit 0dBm 5100 15300   Transmit 0dBM 8800 15840   Transmit 0dBM 3%
Transmit 8dBm 10700 32100   Transmit 8dBm 19000 34200   Transmit 8dBm 6%
Receive 5300 15900   Receive 9000 16200   Receive 2%
UART 24.5 73.5   UART 24.5 44.1   UART -67%
SPI 3.4 10.2   SPI 3.4 6.12   SPI -67%
Processor Running 2600 7800   Processor Running 4100 7380   Processor Running -6%

Is it accurate to consider GLDO in this way? In the datasheet, GLDO is specified at 3.0V, but given it is an LDO, one can assume the same current draw at 1.8V.

  • 0
    TI__Expert 6520 points

    Hi Cole,

    In DCDC mode, the voltage range is 2.2 to 3.8V, but when it is below 2.2V it will dynamically switch to GLDO. In GLDO mode, the voltage range is 1.71 to 3.8 and can operate independently of DCDC mode.

    To answer your question directly - yes, GLDO can use 3V but do expect a higher overall current draw as you have demonstrated in your table.

    Best regards,

    Bun

  • 0 in reply to Bun Kuch
    Prodigy 30 points

    Thanks Bun, that is exactly how DCDC and GLDO mode work, and their voltage ranges.

    You will recognize, I am focused especially on power draw, not necessarily current draw. When comparing power of DCDC at 3V and GLDO at 1.8V, it appears GLDO is more power efficient in some cases. BUT: the GLDO current draw #'s I have used are from the datasheet when measured at 3.0V supplied. Is it fair to use these same measurements when 1.8V is supplied because an LDO operates this way?

    Cole

  • +1 in reply to Cole Mehring
    TI__Expert 6520 points

    Hi Cole,

    I apologize for the misunderstanding. The answer is yes. For a given mode, power draw/efficiency stays the same regardless of voltage so the results for 3V can be used for 1.8V.

    As for GLDO at 1.8V vs DCDC at 3V, it may be more power efficient for certain individual peripherals, but when the radio is turned on you will notice it accounts for a majority of the power draw and GLDO will be overall less efficient.

    Best regards,

    Bun