AnsweredAssumed Answered

STM32L152VC: LCD segments not all 5V tolerant

Question asked by patterson.sheldon on Oct 21, 2014
Latest reply on Oct 22, 2014 by Danish Ali
The STM32L152VC includes an internal voltage regulator with contrast control from 2.60 to 3.51V. Those voltages then get used to drive the individual segments. In my case, I'm running the processor at 2.6V (VD). What I found, however, is that SEG2 (PA3), SEG5 (PB0), and SEG21 (PC3) are only standard 3.3V I/O. Therefore, when these segments are used with an LCD voltage greater than VD, the protection diode on the pin is activated and the processor draws excessive power.

Thankfully I'm not using all possible segments so I can change my segment pins on the next PCB layout to avoid the problem pins. I think this should be listed in the processor errata, otherwise maybe this comment will help someone else avoid the same problem.

Outcomes