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STM8L power (current) consumption problem

Question asked by lim.jisoon on Aug 23, 2011
Latest reply on Dec 11, 2013 by kucherov.ivgeni
 I'm developing some applications with STM8L152R8 and STM8L152M8 MCU now, and both applications are battery-used product. The problem is that, I cannot make the MCU consume micro-ampere order current.

 I used every methods described in the reference guide manual, including low power run mode, active halt mode, and halt mode but our current indicator displayed mA order current consumption, from 1mA to 5mA. Of course I have stoped HSI, LSI, all timers and disabled all interrupts. GPIOs are also retested as push-pull low-slow output mode. I was confused, thus I decided to take out the STM8L discovery board and verify with that evaluation board.

 First, I just delivered power into the discovery board with USB cable. Through toggling the power mode, the LCD of discovery board have shown fine current consumption. About 1mA in run mode, and about 7uA in low-power mode, and below 1uA in halt mode ... it seemed fine.

 However, the result changed with my verification method changing. I switched the IDD jumper to 'OFF' mode, and started verification again. With IDD jumper switch off, the current-measuring circuit should be powerless and the MCU will solely consume the power, I expected so. I connected the precise current measuring multimeter (Agilent 34401A) serially in power supply line (3.3V), and started current consumption measuremnt by ourselves. And the multimeter have shown 30mA of current consumption. Unbelievable, but that's what I've seen. Regardless of MCU power mode, the current consumption was 30mA.

 This is my current situation. Now I cannot be certain of our current consumption method neither the firmware code we've written for MCU low power mode. I want to run our device in active-halt mode with RTC, and the power consumption matter is very important. 

 Little help here, please?

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