LPC4078 FLASHCFG settings.

[yangyu]

Customer operated at 96 MHz CPU frequency with FLASHCFG register reset value 0x3(0011 Flash accesses use 4 CPU clocks. Use for up to 80 MHz CPU clock with power boost off (see Section 3.12.6).) and PBOOST register reset value 0x3(11 : Boost is on, operation up to 120 MHz is supported.).

Is this correct and safe settings?Thanks.

[xiangjun_rong]

Hi, YuYang,

As the following figure, if you use 96MHz CPU clock, you can set the FLASHTIM bits as 0x100(5 cpu clocks with power boost off).

Power boost off can be set up as:

PBOOST=0x00;

I copy it here:

"0100 Flash accesses use 5 CPU clocks. Use for up to 100 MHz CPU clock with power boost off (see Section 3.12.6)."

Hope it can help you

BR

XiangJun Rong

xiangjun_rong_0-1608516052910.png

Power boost control reg

xiangjun_rong_1-1608516519422.png

[yangyu]

Hi Xiangjun,

Thanks for your reply.

In other word,with default reset value of FLASHTIM&Boost the cpu runs at 96MHz is unsafe?

In general,the designers don't notice these registers settings and just use the default value.Any official documents or sample codes to remind users?

[xiangjun_rong]

Hi, Yuyang,

Firstly, I do not think there is any documentation to remind user of the FLASHTIM&Boost registers.

Regarding your question whether it is safe to use the default FLASHTIM(3) and PBOOST(3) when the LPC4078 runs in 96MHz, I can not say it is safe or not.

I suggest you do a full temperature range test, if the chip runs okay in full temperature range especially in high temperature, it is okay.

BR

XiangJun Rong