ETRA SOM/ETRA Hardware/Electrical Thermal and Mechanical Features/Operational characteristics

History
Issue Date	Notes
2020/12/31	First release
2022/09/07	Added power consumption measures
2023/08/03	Update minimum supply voltage

Operational characteristics

Maximum ratings

Parameter	Min	Typ	Max	Unit
Main power supply voltage	-0.5	5	6	V

Recommended ratings

Parameter	Min	Typ	Max	Unit
Main power supply voltage	3.5	5	5.25	V

Output Rails

The ETRA SOM generates internally some power rails that can be used to power the carrier board peripherals.

VDD

Voltage for CPU I/O. It has a typical value of 3.3V. This rail powers the CPU I/O and internal memories.

The maximum ouput current is 500mA from which has to be subtracted the CPU and memories consumptions.

PMIC_3V3

Spare buck converter output. It has a typical value of 3.3V.

The maximum output current is 2A.

BST_OUT

Boost converter output. It has a typical value of 5V. From this rail derives the VBUS_OTG_OUT and VBUS_SW rails.

Thge maximum output current is 1.1A from wich has to be subtracted the VBUS_OTG_OUT and VBUS_SW consumptions

VBUS_OTG_OUT

USB power output switch from PMIC, intended to power the OTG port when configured in HOST mode.

The power switch has an overcurrent protection that switch off this rail over 550mA drain current.

VBUS_SW

USB power output switch from PMIC, intended to power the HOST port.

The power switch has a programmable overcurrent protection that switch off this rail over 600mA (default) or 1.1A drain current.

LDO2

Spare LDO converter output. It can be programmed to source from 1.7V to 3.3V. The default value is 1.8V

The maximum output current is 350mA.

LDO5

Spare LDO converter output. It can be programmed to source from 1.7V to 3.9V. The default value is 2.9V

The maximum output current is 350mA.

1V8

Spare LDO converter output. It can be programmed to source from 0.8V to 3.3V. The default value is 1.8V

The maximum output current is 150mA.

Power consumption

Providing theoretical maximum power consumption value would be useless for the majority of system designers building their application upon ETRA module. Practically speaking, these figures would be of no help when it comes to size power supply unit or to perform thermal design of real systems.

Instead, several configurations have been tested in order to provide figures that are measured on real-world use cases.

Please note that ETRA platform is so flexible that it is virtually impossible to test for all possible configurations and applications on the market. The use cases here presented should cover most of real-world scenarios. However actual customer's application might require more power than values reported here or customer's use case may be differ significantly with respect to the ones here considered.

Therefore, application-specific requirements have always to be taken into consideration in order to size power supply unit and to implement thermal management properly.

Use cases results

Measurements have been performed on the ETRA SOM under test is equipped with:

• STM32MP157 Dual Core A7 3D GPU (p.n. STM32MP157AAB3)
• 512 MB DDR3L
• 8 GB eMMC

Ethernet link has been always disconnected during the test.

The table below reports the power consumption measurements for the considered use cases.

Checkpoint	Power (mW)
SOM under reset	375
Linux prompt	975
Standby (*)	200
Suspend to RAM (**)	50

(*) wakeup from GPIO

(**) wakeup from RTC or GPIO

Wakeup

For RTC wakeup it is possible to use this simple commands:

wakeuptime=`date -d "1 minute" +%s`

rtcwake -lt$wakeuptime

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