Each MCU also has a 4 MHz on-chip RC-oscillator that can be used as the main clock, via PLL, to drive the chip without an external crystal. The IRC is trimmed to 1% accuracy over the entire voltage and temperature range. The MCUs have great flexibility with four 32-bit general purpose timers each with four capture, four compare, and four external outputs. The MCUs also have a watchdog timer that can be generated from multiple clock source options as well as a PWM block that supports 3 phase motor control with “dead time” generation and a low power RTC with 2 KB SRAM for data storage during power down and battery back up.