I am working a design that incorporates the Microchip RT3 Proasic SOC chip mated up to the TMS320C6727B-SP DSP. To perform in--system programming of the SOC device, I need to have the 1.2V rail switch up to 1.5V during the reprogramming sequence for the SOC device. There is currently only a single 1.2V power rail on this board. The DSP does not need to be operational during this event and I can hold it in reset while reprogramming the RT3 SOC.
The DSP would not be operating during this event but would be powered with 1.5 V on its's core Vcc power inputs. The recommended operating range for the DSP is from 1.14 to 1.32V; nominally 1.2V.
The absolute maximum voltage range for these pins is -0.2 to 1.8V. This would never be performed during tactical operation but would occur when first configuring the device in the factory or when an upgrade needs to be performed on this system. Is this approach acceptable? Or, would it be a risky thing to implement? Any technical support that could be offered in addressing this issue would be greatly appreciated.
