SPRAD21E May 2023 – February 2024 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP , AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62P , AM62P-Q1
It is important for the processor VPP (eFuse ROM programming supply) to remain within the ROC range during eFuse programming. An LDO powered from a higher input voltage supply (2.5 V or 3.3 V) is recommended for the LDO to be able to compensate for the voltage drop through its series pass transistor and maintain the correct operating voltage during high load current transients. Local bulk capacitors are recommended near the processor VPP pin to support the LDO transient response.
Using a Load switch or FET configured as a switch to power VPP from another supply rail that has a +/-5% variation could be problematic due to the high load current transient and the VPP power rail having the same supply range requirement. This topology doesn’t account for the voltage drop going through the load switch. The load switch may be an option if the board designer uses power source with smaller variation, such that the supply variation combined with the voltage drop through the load switch never exceeds the VPP recommended operating range.
For more information, see the [FAQ] AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 Custom board hardware design – Queries regarding VPP eFuse programming power supply selection and application. This is a generic FAQ and can also be used for AM62A7 / AM62A3 and AM62P / AM62P-Q1 family of processors.