2008-01-05 07:58 AM
Is it possible co leave Vref+ pin unpowered in Standby ?
2011-05-17 03:20 AM
Hello
I'm going to use STM32 Standby mode (Vdd & Vdda = 3V from battery) but ADC will be working only in Run mode, when main supply (3.3V) will be operating and then Vref+ pin will be powered through LM431C reference at the level of 2,5V. But when main supply will be switched off then conseqently Vref+ will be left unpowered ... I cannot supply Vref+ directly from Vdda because of 2,5V reference requirement. I do not want to do any ADC conwersions when main supply is not working. The question is: Is it a safe / possible solution ? Can be Vref+ left unpowered (but connected to LM431C) in Standby ? I'm afraid of possible current leaks from Vdd/Vdda to Vref+ in this situation.2011-05-17 03:20 AM
Hi,
According to AN2629 : STM32F101xx and STM32F103xx low-power modes and the Reference Manual, It seems that Vref is only available in 100 pins package . In smaller packages, this Power supply ref is bounded internally to VDDA. So, in my understanding you should left it not powered in standby ( where all blocks are Powered off except the VBAT domain)without risks of leakage current, I assume that ST has a good analog design in their rails powers and I/O ring in Low power. You can try it at your end and inform me if you observe additional leaks. Magigimix ;)