Difference between Different Mask Number and also VDD to GND measurement for MPC755CPX350LE

[236855]

Recently I received a new batch of MPC755CPX350LE with different Mask Number (49K76D). Anyone know what is the difference between 49K76D vs 48K76D.

There is no such information in the component datasheet.

Besides that, I also found the measurement between VDD to GND is different for both mask number, the measurement less than 100 Ohm is Accepted?

49K76D = Less Than 100 Ohm
48K76D = More Than 1K Ohm

[Oswalag]

Hello,

You can find the difference in the MPC755 RISC Microprocessor Hardware Specifications table 21, 22 and 23.

Let's talk about the 'B' spec devices first. The 48K76D mask with the thicker gate oxide would be used for these devices. These devices are expected to have a lower power consumption and to be slower devices, but it is not until they are actually tested for power consumption, that it is determined if they are marked as a 'B' or 'C' part.
- If they are indeed low power devices, they become 'B' spec devices with a 48K76D mask code.
- If they consume too much power and do not pass the 'B' spec power test, they are tested to the higher power 'C' spec devices and if they pass that slightly higher (0.7W) power spec they become 'C' spec devices with a 48K76D mask code.

Similarly for the 'C' spec devices ... The 49K76D mask with the thinner gate oxide would be used for these devices. These devices are expected to have a slightly higher (0.7W) power consumption and to be faster devices, but when they are actually tested for power consumption, that is when it will be determined if they are marked as a 'C' or 'B' part.
- If they are indeed higher power, faster devices, they become 'C' spec devices with a 49K76D mask code.
- If they happen to consume lower power and pass the lower 'B' spec power test, they become 'B' spec devices with a 49K76D mask code.

Have a nice day!

[236855]

Hi Oswalag,

Thank you for explaining the difference in Mask Number.

How about the resistance measurement between the VDD to GND?

Is less than 100 Ohm acceptable?

Or what is the actual specification that is consider as acceptable?

[Oswalag]

Hello,

It's not recommend measuring DC resistance between VDD and GND as manufacturing criteria. Attached application note explains why this measurement is highly suspect in today's technologies.

Unless you have reason to think it got damaged during assembly,you have just proven what is normal DC resistance for that particular part. As the app note explains, other parts may exhibit a different value so taking the measurement is not so useful.

[236855]

Hello,

Thank you for the explanation.