SPRADO2A November 2024 – December 2024 AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62D-Q1
An important requirement is 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 (2.5V or 3.3V) is recommended for the LDO to compensate for the voltage drop through the 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.
Powering VPP from a supply rail with a ±5% variation using a load switch or FET can be problematic due to high load current transients and the requirement for the VPP power rail to match the supply range. Load switch or FET topology does not account for the voltage drop going through the load switch. The load switch can 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 [FAQ] AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 Custom board hardware design – Queries regarding VPP eFuse programming power supply selection and application. The FAQ is generic and can also be used for AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62D-Q1 processor families.