i.MX ProcessorsのトピックRe: NVCC_LVDS_2P5 current consumption

NVCC_LVDS_2P5 current consumption

gavinjones — Mon, 30 Sep 2013 15:56:22 GMT

Dear Community,

In my iMX6Q application I am not using the LVDS interface. However, the datasheet states that the NVCC_LVDS_2P5 supply must be provided, as it also powers the DDR I/O pre-drivers. What is the maximum current consumption from this supply when LVDS is not used (the DDR will be used extensively)?

Thanks,

Gavin.

Re: NVCC_LVDS_2P5 current consumption

SergioSolis — Tue, 01 Oct 2013 19:38:54 GMT

Hello Gavin,

You can calculate power measurements using the following application note:

http://cache.freescale.com/files/32bit/doc/app_note/AN4509.pdf

Let me know if you have any questions.

Re: NVCC_LVDS_2P5 current consumption

gavinjones — Wed, 02 Oct 2013 09:01:54 GMT

Hello SerchMX,

AN4509 gives me a typical value for the current consumption into the VDDHIGH_IN pin. However, it does not break this figure down between the direct internal loads (PLLs) and the loads externally connected to the VDDHIGH_CAP pin (including NVCC_LVDS_2P5). Maximum values for a number of the loads are given in the data sheet, section 4.1.5, but NVCC_LVDS_2P5 is not included.

My application already has a 2.5V switching regulator supplying some of the iMX6 IOs. Therefore, for improved power efficiency, I plan to connect all the iMX6 2V5 loads (including NVCC_LVDS_2P5) directly to this rail, rather than to the VDDHIGH_CAP pin. However, I need to know the maximum current consumption of the NVCC_LVDS_2P5 load so as to ensure the switching regulator is rated high enough.

Please can you provide an upper bound for the maximum current consumption of the NVCC_LVDS_2P5 load?

Best regards,

Gavin.

Re: NVCC_LVDS_2P5 current consumption

AnsonHuang — Tue, 15 Oct 2013 06:21:20 GMT

Hi, Gavin

I think you can just use the max VDDHIGH_IN power consumption to be the number you want, although it includes the PLL's power consumption. So ideally this VDDHIGH_IN's power consumption is higher than the actually max power of NVCC_LVDS_2P5. The typical max power of VDDHIGH_IN is around 85mA, so this 85mA exceed your platform's 2p5 power rail's capability? If you really want to get the real max power of NVCC_LVDS_2P5, then you may need to measure the power consumption on our SabreSD board, remove r600 and connect a current meter, then run the max power test case.

Re: NVCC_LVDS_2P5 current consumption

gavinjones — Tue, 15 Oct 2013 08:40:38 GMT

Hi Yongcai,

Thanks for the response. I was hoping for a lower figure, but I can budget for the full 85mA for now. I will make the measurement when we get the board busy.

Best regards,

Gavin.