I have a problem to power i.MX287 using notebook usb

young_future · ‎12-26-2013

I try to power my own i.MX287 board using USB.

The i.MX287 is running well when I use the wall power with the usb power cable which is used for Nexus 5 phone.

But, i.MX287 does not run when I use notebook power with the same usb power cable.

I assume that the problem is occurred because of the current shortage.

But I don't know how to solve this problem.

Does anyone have a idea to solve this problem?

Thank you

Yuri · ‎02-05-2014

Perhaps the problem concerns with the low available current from internal i.MX28

regulators in default (start) configuration. This may take place when external parts

(say, DDR) are fed from i.MX28 PMU.

According to app note AN4199 : “The 5-V source can be taken from a

universal serial bus (USB) connection […]. There is a 100-mA input current

limit when the system is powering up from the Power-Off state. Product designers

should pay attention to ensure the 100 mA is sufficient for the total system

consumption during cold-boot or reboot.”

For 5V only configuration, first please refer to section 4.1.2.1 (VDD5V source only: hardware

configuration) of AN4199. Please pay attention on the schematic, shown on Figure 9 (Hardware

connections for VDD5V-only applications). As for software, please use the recent official Freescale

Linux BSP on the Web. Next, according to section 4.1.2.2 (VDD5V source only: software configuration) :

"For an application that uses the VDD5V source only, NO_DCDC_BATT_SOURCE must be defined on

power_prep.c in the bootlet codes. Additionally, the programmer should ensure that

NO_VDD5V_SOURCE is not defined. For more details, see to the Linux BSP User’s Guide."

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