PMU at AM3352-SOM

Started by vinifr, March 22, 2015, 08:19:54 pm

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Hi Olimex,

In product descrition said: "AM3352-SOM is System on Chip module, which contains Sitara AM3352 Cortex-A8 processor, Power managment, 512MB DDR3 memory". But hehopmajieh said: "Removed PMU Code /We do not use PMU at AM3352-SOM/".

So, i'm confused. Is there a PMU in at AM3352-SOM?

Chester Gillon

The TI reference designs for the AM335x use a TPS65217 Power Management IC (PMIC) to regulate the supplies for the AM335x. The TPS65217 has default supply voltages for the AM335x VDD_CORE and VDD_MPU rails, where the supply voltages can be changed by I2C commands. The adjustable supply voltages for VDD_MPU is to support the AM335x "Device operating performance points (OPPs)" which is a combination of supply voltage and maximum ARM Cortex-A8 operating frequency, which allows a selection of either best power consumption or best processing performance.

Instead of using a TPS65217, the AM3352-SOM board revision C uses a set of SY8009AAAC regulators which provide fixed voltages; 1.25V for VDD_MPU and 1.1V for VDD_CORE. The use of a fixed 1.25V for VDD_MPU means the Cortex-A8 in the AM3352 may be operated at a maximum frequency of 800 MHz (aka Turbo OPP) even though an AM3352 with a "1-GHz Cortex-A8" device speed grade is fitted to the AM3352-SOM board.




I have another question. Why they did not use TPS65217?  :o

Chester Gillon

Quote from: vinifr on March 30, 2015, 10:53:27 pmWhy they did not use TPS65217?  :o
According to the TPS65217 wasn't used due to being expensive.

There was also mention of "Linux with cut off vendor locked crap", but not sure if the vendor locked issue was with the TPS65217 support in the Linux Kernel or something else.


TPS65217 alone cost more than quad code SoC from Allwinner
the TI Linus SDK doesn't work if you have no TI PMU on board, you can guess why