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MPC8260A(Hip4) startup problem?

Question asked by meng junling on Oct 27, 2015
Latest reply on Nov 5, 2015 by meng junling

Hi:

Now I buy MPC8260ACZUMHBB chips from RS,  and assembly on my board.

I read the PVR and IMMR, the values indicates Hip4 revision, the package marking (4K25A QQDK1036 MALAYSIA) is identical to PVR/IMMR.

 

Now I have a new problem, when I power up my board, the UART(from SMC1) can't output anything, but keep powering on after about several minutes, I reset my board or recycle the power,

UART can output correctly, I don't know why?

 

But another board assembled MPC8260(Hip3) device boots correctly everytime, and the only difference between two board is different CPU revisions(one is Hip3, another is Hip4).

 

In my design I don't control the power sequence,VDD_Core(1.8V) and VDDH(3.3V) power up at the same time, but the VDD_Core powers quickly,

In AN2290, I find the following states, I want to know if the power sequence affect the MPC8260 boot and cause my problem?

 

2.3 Power Sequencing

One consequence of multiple power supplies is that when power is initially applied the voltage rails ramp

up at different rates. The rates depend on the nature of the power supply, the type of load on each power

supply, and the manner in which different voltages are derived. The following restrictions apply:

• VDD/VCCSYN—Must not exceed VDDH by more than 0.4 V at any time, including during

power-on reset.

• VDDH—Can exceed VDD/VCCSYN by 3.3 V during power on reset by no more than 100 msec.

During normal operation, should not exceed VDD/VCCSYN by more than 2.0 V (HiP3) or 2.5V

(HiP4).

• VIN—Must not exceed VDDH by more than 2.5 V at any time, including during power-on reset.

 

I

On my board, the spare pins U5, V4, and AE11 (on PCI devices, AE11 is CLKIN2) is grouded.

and the AF25(PCI_MODE#) pin is pulled up. XFC pin capacitor is 1200pF.  Clocking setting is 200/133/66Mhz(0101_111, Local mode), clock input is 66Mhz

The Local bus interface is not used, so I left it floating, only fewer pins is connected.

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