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CGE Power Consumption

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Cisco Employee

High Level Calculation of CGE power consumption:

STM32: 72mA @ 3.3V (Run mode, all periperals enabled, 120MHz fHCLK, TA=105degC)

CC1200: 46mA @ 3.3V (RF TX)

SKY65313: 826mA @ 4.3V (RF TX)

38.88MHz TCXO: ~2mA

+ additional couple mA for pull-up/downs, LEDs, etc.

Some basic test of the power consumption has been performed, with below as reference:

Essentially there are 3 main power consumers in the reference design:

  1. 3.3V supply to STM32 MCU

  2. 3.3V supply to RF chipset

  3. 5V supply to RF chipset (regulated down to 4.3V via LDO)

First I performed some RMS current measurements on each supply during idle, receive, and transmit using the “RFTest” firmware.

3.3V MCU

3.3V RF

5V RF

Idle

43mA

16mA

2.7mA

Receive

43mA

39mA

2.7mA

Transmit (mode 1)

43mA

62mA

710mA

In demo mode, the current profile on the 5V RF supply during the transmission is measured,  the current transient lasts 535.8ms and the RMS current consumed 668.8mA during the transmission.

test1.png

Below is the current profile for the 3.3V RF supply during the transmission of the same packets.  About 60mA RMS during transmission, and about 38mA RMS while not transmitting (i.e. receive mode).

test2.png

And here’s the current profile for the 3.3V MCU over a 10s period running the same firmware.  It’s about 42mA RMS on average.

test3.png

current consumed by other mesh data transmissions will be highly dependent upon the # of packets, packet length, transmission duty cycle, sync schedule, etc, current consumed by other mesh data transmissions will be highly dependent upon the # of packets, packet length, transmission duty cycle, sync schedule, etc,

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