Abstract: A microcontroller unit comprises a reset controller operably coupled to a plurality of logic elements of the microcontroller unit. Low voltage detection logic is operably coupled to the reset controller and arranged to provide a plurality of low voltage interrupt signals to a number of respective logic elements of the microcontroller unit via the reset controller. A method of operating a microcontroller unit is also described.

Abstract: A microcontroller unit comprises a reset controller operably coupled to a plurality of logic elements of the microcontroller unit. Low voltage detection logic is operably coupled to the reset controller and arranged to provide a plurality of low voltage interrupt signals to a number of respective logic elements of the microcontroller unit via the reset controller. A method of operating a microcontroller unit is also described.

Abstract: An indication that a power supply is ramped up to a threshold level is received. A circuit is woken up in response to receiving the indication if a control field of configuration information is in a first state, and the circuit is not woken up in response to receiving the indication if the control field of configuration information is in a second state.

Abstract: An integrated circuit has an internal oscillator circuit for being connected to an external frequency source such as a crystal or a ceramic resonator. The internal oscillator circuit has an inverting amplifier across the frequency source terminals to establish an oscillation there. One terminal of the frequency source is coupled to one input of the comparator and to a second input of the comparator through a low pass filter. Coupling the output of the low pass filter to the second input of the comparator is for preventing a DC offset from developing between the two inputs of the comparator. The other terminal of the frequency source is coupled to the second input of the comparator through a high pass filter. The high pass filter provides the comparator with a larger voltage differential to increase noise margin. Noise margin is further improved by allowing an increase in hysteresis in the comparator.

Abstract: A reference circuit provides a reference voltage and a reference current that are both temperature and a power supply voltage independent. The reference circuit includes a bandgap reference circuit, a current source, and a resistor. The bandgap reference circuit provides a feedback voltage to control the current source and thereby generate a temperature independent voltage and a PTAT (proportional to absolute temperature) current. A resistor having a positive temperature coefficient is coupled to the feedback controlled current source to provide a CTAT (complementary to absolute temperature) current. The CTAT current is summed directly into the feedback controlled current source to produce a reference current that is substantially constant over a range of temperatures.

Abstract: Power saving method is achieved by weakly holding a signal line in its last in time state, which is responsive to and may be overcome by the state of an external signal. During sleep mode, the weakly held signal line state tracks and holds the external signal using alternatively a controllable weak pull-up or pull-down device, such that weakly held state may be driven to a different state by the external driving signal with slight power consumption. When sleep mode is off, the keeper function is disabled and the signal line maybe driven alternatively internally or externally depending upon the state of an enable line.

Abstract: Circuits in a processor may provide an indication that power supplies are ready when waking from a reduced power state. The processor may include timers to measure a period of time, and may utilize voltage detectors to detect the voltages on the power supplies. A control register in the processor may influence the operation.

Abstract: A circuit includes an input terminal, an output terminal and a latch. The input terminal receives an input signal. The latch is programmable with a value. The latch communicates the input signal to the output terminal in response to the circuit not being in a sleep mode and in response to the circuit being in the sleep mode, furnishes a second signal to the output terminal indicative of the value.

Abstract: A circuit includes an input terminal, an output terminal and a latch. The input terminal receives an input signal. The latch is programmable with a value. The latch communicates the input signal to the output terminal in response to the circuit not being in a sleep mode and in response to the circuit being in the sleep mode, furnishes a second signal to the output terminal indicative of the value.