topic Ls1046 abnormal crash in Layerscape

Ls1046 abnormal crash

411243223 — Mon, 19 Aug 2019 09:32:21 GMT

Hi, I meet a problem: I desigend a board with ls1046(1.2GHz), reffer to ls1046rdb. A simple boot which print i++, runs and abnormally crash with no time regularity, maybe crash in a few seconds or in a few minutes or one hour.

I have measured the power supply & clk , nothing abnormal found.

I found that, the signal "hreset" may drop down a short time, "hreset" I use as input signal,4.7K res pull up, that means I do not drive on the signal . I also found "ifc_clk" change from 50MHz to 12.5MHz, when Ls1046 crash., If not crash ,it will be always 50MHz. So, it seems LS1046'PLL crash.

One mistake is that, I used 1.0v to power the vdd, when I check the datasheet, it should be 0.9v(1.2Ghz), will this destroy the IC? I have correct the vdd to 0.9v, but I cannot find anything abnormal in these days. may somebody help me ?

Thanks a lot.

Re: Ls1046 abnormal crash

411243223 — Thu, 22 Aug 2019 09:00:46 GMT

Problem is solved．

First, 1.0V vdd will not damage ls1046 of 1.2GHz version.

Second, on my board, the "poreset_B" signal is interfered by the board main power, which is DC_12V. I found that, the higher Voltage　of power(like 13V), more possibly LS1046 crash. And when I measured the "poreset_B" signal , Ls1046 can run well.

So, I suggest "poreset_B" have ａresistance pullup and 22pF cap to ground, that will be beneficial.

Re: Ls1046 abnormal crash

411243223 — Tue, 27 Aug 2019 01:29:46 GMT

I have thinking about why "poreset_b" be interfaced these days, And found the vdd power ltc3866 may have some problem . I designed the ltc3866 reffer to the demo, but much high overshoot (p2p 22v max)found on the "sw" pin, that will worsen　the board power supply dc-12v, and the the dc-12v interfaces the "poreset_b".

I check the datasheet of ltc3866, and want to ask why "sgnd"&"gnd" are not one net, but connect them by 0Ω-res(on the bom ,there is no this ０Ω unexpectedly )? Dose anybody have the same problem?

Thanks.