IC failure

Hello,

when calculating the failure rate of a microcontroller should the lambda_0_th be simply 0.075, or should every part of the microcontroller be considered and evaluated separately? For example,

• 0.075 for the core,
• 0.053 for the internal SRAM,
• 0.06 for internal Flash and 3x0.021 for the GPIO/PWM and I2C modules.

Obviously the latter results in a much higher failure rate so using that (even if incorrect) would mean an error towards safety but i wonder what the authors had in mind.