Leakage Current Issue with STM32F103R8T6 in Standby Mode

[chiranjeeva]

Hello everyone,

I'm encountering an issue with a circuit that incorporates an STM32F103R8T6 microcontroller. In my design, the MCU's VDD domain is powered by a battery, while an external supply is used for the analog reference (VDDA). When the circuit is in standby mode with both power supplies connected, the current draw is approximately 2.8 µA. However, if I disconnect the external supply (i.e., the one powering VDDA), the battery current consumption increases to nearly 200 µA.

This behavior leads me to suspect that there might be a leakage current from the VDDA domain into the rest of the circuit. Has anyone experienced something similar or can offer insights on potential causes for this discrepancy? I’m wondering if this could be due to a design oversight, an unintended leakage path, or perhaps an inherent characteristic of the STM32F103R8T6 when operating in standby mode.

Below, I have attached the code that I used for testing standby mode with CubeIDE, along with the schematic of the circuit.

Any help or suggestions would be greatly appreciated!

Thanks in advance.

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file           : main.c
 * @brief          : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2025 STMicroelectronics.
 * All rights reserved.
 *
 * This software is licensed under terms that can be found in the LICENSE file
 * in the root directory of this software component.
 * If no LICENSE file comes with this software, it is provided AS-IS.
 *
 ******************************************************************************
 */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
RTC_HandleTypeDef hrtc;

/* USER CODE BEGIN PV */
uint8_t x;
uint64_t count = 0;
uint8_t w = 0;
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_RTC_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
 * @brief  The application entry point.
 * @retval int
 */
int main(void) {

	/* USER CODE BEGIN 1 */

	/* USER CODE END 1 */

	/* MCU Configuration--------------------------------------------------------*/

	/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
	HAL_Init();

	/* USER CODE BEGIN Init */

	/* USER CODE END Init */

	/* Configure the system clock */
	SystemClock_Config();

	/* USER CODE BEGIN SysInit */

	/* USER CODE END SysInit */

	/* Initialize all configured peripherals */
	MX_GPIO_Init();
	MX_RTC_Init();
	/* USER CODE BEGIN 2 */
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);

	/* USER CODE END 2 */

	/* Infinite loop */
	/* USER CODE BEGIN WHILE */
	while (1) {
		x = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_9);
		if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_9)) {
			count++;
			HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN1);

		}
		HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_1);
		HAL_Delay(100);
		w++;
		/* USER CODE END WHILE */

		/* USER CODE BEGIN 3 */
	}
	/* USER CODE END 3 */
}

/**
 * @brief System Clock Configuration
 * @retval None
 */
void SystemClock_Config(void) {
	RCC_OscInitTypeDef RCC_OscInitStruct = { 0 };
	RCC_ClkInitTypeDef RCC_ClkInitStruct = { 0 };
	RCC_PeriphCLKInitTypeDef PeriphClkInit = { 0 };

	/** Initializes the RCC Oscillators according to the specified parameters
	 * in the RCC_OscInitTypeDef structure.
	 */
	RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI
			| RCC_OSCILLATORTYPE_HSE;
	RCC_OscInitStruct.HSEState = RCC_HSE_ON;
	RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
	RCC_OscInitStruct.HSIState = RCC_HSI_ON;
	RCC_OscInitStruct.LSIState = RCC_LSI_ON;
	RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
	RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
	RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
	if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
		Error_Handler();
	}

	/** Initializes the CPU, AHB and APB buses clocks
	 */
	RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
			| RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
	RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
	RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
	RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
	RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

	if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) {
		Error_Handler();
	}
	PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
	PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
	if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
		Error_Handler();
	}
}

/**
 * @brief RTC Initialization Function
 *  None
 * @retval None
 */
static void MX_RTC_Init(void) {

	/* USER CODE BEGIN RTC_Init 0 */

	/* USER CODE END RTC_Init 0 */

	/* USER CODE BEGIN RTC_Init 1 */

	/* USER CODE END RTC_Init 1 */

	/** Initialize RTC Only
	 */
	hrtc.Instance = RTC;
	hrtc.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
	hrtc.Init.OutPut = RTC_OUTPUTSOURCE_ALARM;
	if (HAL_RTC_Init(&hrtc) != HAL_OK) {
		Error_Handler();
	}
	/* USER CODE BEGIN RTC_Init 2 */

	/* USER CODE END RTC_Init 2 */

}

/**
 * @brief GPIO Initialization Function
 *  None
 * @retval None
 */
static void MX_GPIO_Init(void) {
	GPIO_InitTypeDef GPIO_InitStruct = { 0 };
	/* USER CODE BEGIN MX_GPIO_Init_1 */
	/* USER CODE END MX_GPIO_Init_1 */

	/* GPIO Ports Clock Enable */
	__HAL_RCC_GPIOC_CLK_ENABLE();
	__HAL_RCC_GPIOD_CLK_ENABLE();
	__HAL_RCC_GPIOA_CLK_ENABLE();

	/*Configure GPIO pin Output Level */
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET);

	/*Configure GPIO pins : PC13 PC14 PC15 */
	GPIO_InitStruct.Pin = GPIO_PIN_13 | GPIO_PIN_14 | GPIO_PIN_15;
	GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
	HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

	/*Configure GPIO pin : PA1 */
	GPIO_InitStruct.Pin = GPIO_PIN_1;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
	HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

	/*Configure GPIO pin : PA9 */
	GPIO_InitStruct.Pin = GPIO_PIN_9;
	GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
	GPIO_InitStruct.Pull = GPIO_PULLDOWN;
	HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

	/* USER CODE BEGIN MX_GPIO_Init_2 */
	/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
 * @brief  This function is executed in case of error occurrence.
 * @retval None
 */
void Error_Handler(void) {
	/* USER CODE BEGIN Error_Handler_Debug */
	/* User can add his own implementation to report the HAL error return state */
	__disable_irq();
	while (1) {
	}
	/* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  *   file: pointer to the source file name
  *   line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

[Andrew Neil]

---

@chiranjeeva wrote:

a circuit that incorporates an STM32F103R8T6 microcontroller

---

Are you sure it's a genuine ST chip ?

[chiranjeeva]

Yes,I ordered it from the LCSC and ST is the manufacturer.

[Andrew Neil]

Here: https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU-SOC_STMicroelectronics-STM32F103R8T6_C46034.html?s_z=n_stm32 ?

Not sure they're an Official Distributor?

https://www.st.com/content/st_com/en/contact-us.html

[chiranjeeva]

Ya ,I use original chip.The reason I designed the circuit this way is that I want the MCU to run in low-power mode to periodically check and update the status of a pin when the main power supply is switched off. When the main power is available, it powers both VDD and VDDA, but when there is a power outage, only VDD remains powered from the battery.Given this requirement, what would be the best approach to ensure proper operation in low-power mode when the main power supply is switched off?

[Andrew Neil]

https://wiki.st.com/stm32mcu/wiki/Introduction_to_Low_power_with_STM32

AN4899, STM32 microcontroller GPIO hardware settings and low-power consumption:
https://www.st.com/resource/en/application_note/an4899-stm32-microcontroller-gpio-hardware-settings-and-lowpower-consumption-stmicroelectronics.pdf

AN2586, Getting started with STM32F10xxx hardware development:

https://www.st.com/resource/en/application_note/an2586-getting-started-with-stm32f10xxx-hardware-development-stmicroelectronics.pdf

via: https://www.st.com/en/microcontrollers-microprocessors/stm32f103r8.html#documentation

The STM32CubeF1 package includes examples demonstrating low-power modes.

And remember that low-power is not just about the microcontroller - it includes the firmware, and the rest of the hardware.