Abstract: A DC-DC converter for generating a DC output voltage includes: a digitally controlled pulse width modulator (DPWM) for controlling a switching power stage to supply a varying voltage to an inductor; and a digital voltage feedback circuit for controlling the DPWM in accordance with a feedback voltage corresponding to the DC output voltage, the digital voltage feedback circuit including: a first voltage controlled oscillator for converting the feedback voltage into a first frequency signal and to supply the first frequency signal to a first frequency discriminator; a second voltage controlled oscillator for converting a reference voltage into a second frequency signal and to supply the second frequency signal to a second frequency discriminator; a digital comparator for comparing digital outputs of the first and second frequency discriminators and for outputting a digital feedback signal; and a controller for controlling the DPWM in accordance with the digital feedback signal.

Abstract: A DC-DC converter for generating a DC output voltage includes: a digitally controlled pulse width modulator (DPWM) for controlling a switching power stage to supply a varying voltage to an inductor; and a digital voltage feedback circuit for controlling the DPWM in accordance with a feedback voltage corresponding to the DC output voltage, the digital voltage feedback circuit including: a first voltage controlled oscillator for converting the feedback voltage into a first frequency signal and to supply the first frequency signal to a first frequency discriminator; a second voltage controlled oscillator for converting a reference voltage into a second frequency signal and to supply the second frequency signal to a second frequency discriminator; a digital comparator for comparing digital outputs of the first and second frequency discriminators and for outputting a digital feedback signal; and a controller for controlling the DPWM in accordance with the digital feedback signal.

Abstract: The solder-joint integrity of digital electronic packages, such as FPGAs or microcontrollers that have internally connected input/output buffers, is evaluated by applying a time-varying voltage through one or more solder-joint networks to charge a charge-storage component. Each network includes an I/O buffer on the die in the package and a solder-joint connection, typically one or more such connections inside the package and between the package and a board. The time constant for charging the component is proportional to the resistance of the solder-joint network, hence the voltage across the charge-storage component is a measurement of the integrity of the solder-joint network.

Abstract: A solder-joint detection circuit uses a resistive bridge and a differential detector to detect faults in the solder-joint network both inside and outside the digital electronic package during operation. The resistive bridge is preferably coupled to a high supply voltage used to power the package. Resistors R1 and R2 are connected in series at a first junction between the high and low supply voltages and a resistor R3 is coupled to the high supply voltage and connected in series with the resistance of the solder-network at a second junction. The network is held at a low voltage on the die. The detector compares the sensitivity and detection voltages and outputs a Pass/Fail signal for the solder-joint network.