8-bit PIC® MCU Power-Up Timer (PWRT)

Last modified by Microchip on 2023/11/09 09:02

The Power-up Timer (PWRT) provides a nominal 72-millisecond delay after a Power On Reset (POR), Brown Out Reset (BOR), or after the Master, Clear Pin External Reset (MCLR) pin reset is initiated. The PWRT operates on a dedicated internal RC oscillator. The device is kept in reset as long as the PWRT has not timed out. The PWRT allows the Vdd voltage of the PIC® MCU to rise to an acceptable level before operating. The PWRT delay may vary from device to device due to Vdd, temperature, and process variations. The DC parameters section of the device datasheet will specify the details.

For most applications, we recommend enabling the PWRT, especially when the Brown Out Reset (BOR) is enabled since the voltage level of brownout may be just below the trigger point and the extra PWRT delay will guarantee a stable return from reset.

PWRT Configuration

The PWRT has an enable/disable bit in the configuration registers for the device. For newer devices, the PWRTE bit is set to zero (0) to enable the PWRT. On older devices, the enable is set to one (1). Refer to the device datasheet to confirm the proper setting.

The PIC16F1713/6 datasheet shows the PWRTE bit in the CONFIG1 register.

pwrt config