APB1 peripheral clock enable in low power mode register
| TIM2LPEN | TIM2 clock enable during Sleep mode |
| TIM3LPEN | TIM3 clock enable during Sleep mode |
| TIM4LPEN | TIM4 clock enable during Sleep mode |
| TIM5LPEN | TIM5 clock enable during Sleep mode |
| WWDGLPEN | Window watchdog clock enable during Sleep mode |
| SPI2LPEN | SPI2 clock enable during Sleep mode |
| SPI3LPEN | SPI3 clock enable during Sleep mode |
| USART2LPEN | USART2 clock enable during Sleep mode |
| I2C1LPEN | I2C1 clock enable during Sleep mode |
| I2C2LPEN | I2C2 clock enable during Sleep mode |
| I2C3LPEN | I2C3 clock enable during Sleep mode |
| PWRLPEN | Power interface clock enable during Sleep mode |