GreenPAK and GreenFET
6 months ago
Posted byKlaus Moelholm70 points 9 repliesHi
I have a SLG46824 design that seemed to work ok, but because of some power consumption issues, we tried to move the I2C pull-up resistors from the SLG46824 supply to an other 3.3V supply, which is not on when the SLG46824 powers up. This had the effect that the logic in the SLG46824 NVM stopped functioning! Can it really be correct that SDA and SCL must be pulled high during power up, for the SLG46824 to power up correctly and function?
Best regards Klaus Moelholm
6 months ago
Hi Oleh,
的SLG46824 was programmed before the chip start up. I am not using the I2C, it is for future use.
Best regards,
Klaus Moelholm
6 months ago
Klaus,
Thank you for the feedback,
I couldn't replicate this issue using my testbench. Could you please tell if you were using some specific condition like increased temperature, VDD, supply ramp? How many ICs had such behavior, is it a one-time issue or do you observe it all the time? Did you use our development board to program the chip?
Best regards,
Oleh Sapiha
6 months ago
Oleh,
Normal temperature around 25C.
VDD is a 3.3V supply (TPS7A1633DRBR) that rises in 300 us in a single nice flat monotonous slope, with a small overshoot to 3.35 V.
We have only tested this on one board, because it requires manipulating 0201 components, so it is not so easy.
的SLG46824 was non functional all the time when SCL and SDA was connected to the other 3.3V supply. While the SDA and SCL pull-up resistors was connected to the other 3.3V supply, we tried to connect SCL and SDA to VDD during power-up with a wire and then the SLG46824 was functional. Now that we reconnected the SDA and SCL pull-up resistors to VDD again , then the SLG46824 is functional again.
的SLG46824 is actually a custom part with the SLG4BD44950 part number, so it was delivered programmed from the factory to us. But because we found an other issue, where we had to change some of the internal pull-up resistors in the SLG4BD44950 from 1 MOhm to 100 kOhm, it was reprogrammed with the serial debugger.
Best regards,
Klaus Moelholm
5 months ago
Oleh,
I couldn't replicate this issue using the Universal Dev. Board 1, so I guess that the issue only occurs when VDD rises in some specific way or depends on some other conditions?
Best regards,
Klaus Moelholm
5 months ago
You're back-powering the GreenPAK via the external pullups. You are not supposed to be driving their I/Os above VDD or else weird stuff happens (like no POR).
6 months ago
Hi Klaus,
Thank you for your appeal. Could please tell if the NVM in SLG46824 was programmed before the chip start up? Of you are trying to Emulate chip using I2C?
Best regards,
Oleh Sapiha