SPRAD21I May 2022 – September 2025 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP , AM62A1-Q1 , AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62D-Q1 , AM62P , AM62P-Q1
VPP (eFuse ROM programming) supply used for programming the processor eFuse is recommended to be sourced (powered) from a separate LDO that support the required (refer processor-specific data sheet) load current, load current transient and active (quick) output discharge. The LDO is recommended to be enabled only during eFuse programming. VPP operating voltage is required to be within the ROC range during eFuse programming. An LDO powered from a higher input voltage (2.5V or 3.3V) is recommended 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 supply rail from a supply rail with a variation outside the ROC (±5%), or using a Load switch or FET based switch can be a concern due to high load current transients and the requirement for the VPP supply rail be within the processor supply ROC. Load switch or FET based switch topology does not account for the voltage drop going through the load switch. The load switch can be an option if the custom board designer uses power source with smaller variation (compared to ROC), such that the supply variation combined with the voltage drop through the load switch never exceeds the VPP recommended operating range. As an alternate approach, an external supply for programming the eFuse can be used. The supply requirements are similar to the on-board LDO and the recommendation is to time the external supply EN (enable) using one of the processor IO. When external VPP supply is used, the recommendation is to provision for the bulk and decoupling capacitor on the processor board near to VPP supply pin.
For more information, see the following FAQ:
The FAQ is generic and can also be used for AM62Ax (AM62A7, AM62A7-Q1, AM62A3, AM62A3-Q1, AM62A1-Q1), AM62D-Q1 and AM62Px (AM62P, AM62P-Q1) processor families.