Supply Requirements¶
The MitySOM-335x SoM is powered by an external 3.3 Volt to 5.0 Volt power supply. This power supply is used to derive additional voltages on the module. Actual power utilization of these modules is highly dependent on the application and factors such as:
- CPU clock rates
- Peripherals powered up or down
- Utilization of CPU
- Graphical Usage
The supply information provided is the maximum possible given the on-board power supply design on the module. This information is provided for designers sizing an external power supply. In the majority of applications the module will draw far less than the design maximums provided here.
| Supply (V) | Max Current (mA) | Max Power (mW) |
| 3.3 | 4050 | 13,450 |
Note: There are 8 VIN input pins on a MitySOM-335x SoM with a limit of 500mA each making total current draw limited to 4.0A.
Measured 3.3V power draw for various uses¶
This section attempts to give you a better feel for module power draw under various configurations. The power consumption here includes the entire module, not just the AM335x. It includes the on-board DC to DC converters, power good LED status, the AM335x, the NAND FLASH, SPI FLASH, and miscellaneous crystals, etc.
100% CPU load achieved by running the following command from the serial port: dd if=/dev/zero of=/dev/null &
MitySOM-3359-GX-226 (DDR2 256MB RAM/256MB NAND modules)¶
Frequency Testing (Same module):
Please visit the http://support.criticallink.com/redmine/projects/armc8-platforms/wiki/MityARM-335x_Frequency_Scaling page for information on modifying the clock speed of a module.
| Module | CPU Clock | Peripherals | ARM Load (%) | Notes | I (mA) | Power (mW) |
| MitySOM-3359 | 720 MHz | Booted only into UBoot | N/A | Uboot Only no OS running | 240 | 792 |
| MitySOM-3359 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP | 0 | Linux Only (No Demo, Monitor or Mouse) | 300 | 990 |
| MitySOM-3359 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, | 100 | Linux Only (No Demo, Monitor or Mouse) | 430 | 1420 |
| MitySOM-3359 | 600 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP | 0 | Linux Only (No Demo, Monitor or Mouse) | 295 | 975 |
| MitySOM-3359 | 600 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, | 100 | Linux Only (No Demo, Monitor or Mouse) | 390 | 1290 |
| MitySOM-3359 | 275 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP | 0 | Linux Only (No Demo, Monitor or Mouse) | 250 | 830 |
| MitySOM-3359 | 275 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, | 100 | Linux Only (No Demo, Monitor or Mouse) | 290 | 960 |
Matrix GUI Demonstration Running
| Module | CPU Clock | Peripherals | ARM Load (%) | Notes | I (mA) | Power (mW) |
| MitySOM-3359 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 0 | ARM Demo Running w/Monitor and Mouse Connected | 300 | 1000 |
| MitySOM-3359 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 30 | ARM Demo Running w/3D Demo Displayed and Mouse | 480 | 1580 |
| MitySOM-3359 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 100 | ARM Demo Running w/3D Demo Displayed and Mouse | 520 | 1720 |
| MitySOM-3359 | 600 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 0 | ARM Demo Running w/Monitor and Mouse Connected | 280 | 925 |
| MitySOM-3359 | 600 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 30 | ARM Demo Running w/3D Demo Displayed and Mouse | 450 | 1490 |
| MitySOM-3359 | 600 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 100 | ARM Demo Running w/3D Demo Displayed and Mouse | 500 | 1650 |
| MitySOM-3359 | 275 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 0 | ARM Demo Running w/Monitor and Mouse Connected | 254 | 840 |
| MitySOM-3359 | 275 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 30 | ARM Demo Running w/3D Demo Displayed and Mouse | 380 | 1250 |
| MitySOM-3359 | 275 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 100 | ARM Demo Running w/3D Demo Displayed and Mouse | 380* | 1250 |
Note*: It seems that at a lower CPU speed with the 3D demo running increasing the cpu load to 100% with the dd test does not appear to increase load/usage.
MitySOM-3354-GX-X38 (DDR3 512MB RAM/512MB NAND modules)¶
| Module | CPU Clock | Peripherals | ARM Load (%) | Notes | I (mA) | Power (mW) |
| MitySOM-3354 | 720 MHz | Booted only into UBoot | N/A | Uboot Only no OS running | 300 | 990 |
| MitySOM-3354 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP | 0 | Linux Only (No Demo, Monitor or Mouse) | 340 | 1122 |
| MitySOM-3354 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, | 100 | Linux Only (No Demo, Monitor or Mouse) | 450 | 1485 |
| MitySOM-3354 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 0 | ARM Demo Running w/Monitor and Mouse Connected | 338 | 1115 |
| MitySOM-3354 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 30 | ARM Demo Running w/3D Demo Displayed and Mouse | 497 | 1640 |
| MitySOM-3354 | 720 MHz | 3 Uarts, SPI, 1 EMAC, I2C, RTC, EMIFA, 2xUSB, McASP, HDMI Display | 100 | ARM Demo Running w/3D Demo Displayed and Mouse | 520 | 1720 |
Current/Power Measurement HW/SW Information (Using 335x Development Kit Baseboard)¶
Through the use of a gain amplifier, INA145UA (U100), and an I2C Analog to Digital converter, ADS1000A0IDBVT (U101) the module is able to read the voltage across a resistor, R110, which is in series with the power supply to the MitySOM-335x SoM. The amplifier is set with a gain of 27 through the use of R135 and R136 in conjunction with U100.
UBoot Example:¶
Please see the following wiki page for information on using the current monitor IC from UBoot (http://support.criticallink.com/redmine/projects/am335x-devkit/wiki/I2C0_Current_Monitor_IC).
Linux Example:¶
A voltage across R110 of .028V is read by the ADC as 0.769V because of the gain through U100. Included in the root filesystem on the SD card provided with a development kit resides a script called sh_modpwr. The sh_modpwr script reads this ADC value and divides it by 27 which results in the "Voltage across R110" value as shown below. The current is determined to be 10,000 times the voltage across R110.
Output of sh_modpwr script:
Voltage across R110 = 0.028 V
Current through R110 = 284.1 mA
Power used by SOM = 937.4 mW
This script is located in the /usr/bin directory on the SD card and can be viewed/edited at that location.
VBACKUP (PMIC RTC Backup) Current Draw¶
Measurements were taken using a 3V supply in place of a coin cell battery using the MitySOM-335x development kit with an 80-000509RL-1C MitySOM-3359 board (DDR2, 256 MB).
With 3.3VIN applied, current consumption measured was less than 1 micro amp (limited by test equipment).
With 3.3VIN powered down and the PMIC RTC enabled and active, the current consumption of the VBACKUP was measured at 10.2 micro amps.
TiWi-R2 802.11 WiFi Module Current Draw¶
Below are measurements taken for the power draw of ONLY the TiWi-R2 WiFi Expansion Board when used with Critical Link's MitySOM-335x development kit in a streaming video application.
3.3V = 115 mA average
1.8V = 15 mA average
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