Abstract: Embodiments of a multi-mode transition circuit for a DC-DC converter and a DC-DC converter are disclosed. In an embodiment, a multi-mode transition circuit for a DC-DC converter includes a transconductance amplifier operably connected to a first resistor-capacitor (RC) network and switches, a comparator operably connected to a second RC network, where the first and second RC networks are operably connected to a reference voltage, a multiplexer operably connected to the transconductance amplifier and the comparator, and an operation mode selector configured to enable or disable the transconductance amplifier and turn on or off the switches in a sequence when transitioning between a pulse-frequency modulation (PFM) mode and a pulse-width modulation (PWM) mode.

Abstract: One example discloses an open-circuit detector, comprising: a first current source configured to inject a current at an output of a closed-loop circuit; a detector configured to monitor a voltage of the closed-loop circuit; wherein the detector is configured to indicate whether the voltage monitored exceeds a predetermined threshold voltage; a controller configured to regulate the current injected by the first current source; wherein the controller is configured to set an open-circuit flag if the current injected caused the voltage to exceed the predetermined threshold voltage.

Abstract: One example discloses an open-circuit detector, comprising: a first current source configured to inject a current at an output of a closed-loop circuit; a detector configured to monitor a voltage of the closed-loop circuit; wherein the detector is configured to indicate whether the voltage monitored exceeds a predetermined threshold voltage; a controller configured to regulate the current injected by the first current source; wherein the controller is configured to set an open-circuit flag if the current injected caused the voltage to exceed the predetermined threshold voltage.

Abstract: Embodiments of a multi-mode transition circuit for a DC-DC converter and a DC-DC converter are disclosed. In an embodiment, a multi-mode transition circuit for a DC-DC converter includes a transconductance amplifier operably connected to a first resistor-capacitor (RC) network and switches, a comparator operably connected to a second RC network, where the first and second RC networks are operably connected to a reference voltage, a multiplexer operably connected to the transconductance amplifier and the comparator, and an operation mode selector configured to enable or disable the transconductance amplifier and turn on or off the switches in a sequence when transitioning between a pulse-frequency modulation (PFM) mode and a pulse-width modulation (PWM) mode.

Abstract: A method for current limiting an operational amplifier includes sensing a first current through a first branch of the operational amplifier. The first branch conducts the first current from a limited current supply connected to an operational amplifier output. The first current is compared to a reference current to generate a regulation signal. A variable current source is controlled with the regulation signal. An output current of a transconductance amplifier is limited with the variable current source to limit the first current in response thereto.

Abstract: A method for current limiting an operational amplifier includes sensing a first current through a first branch of the operational amplifier. The first branch conducts the first current from a limited current supply connected to an operational amplifier output. The first current is compared to a reference current to generate a regulation signal. A variable current source is controlled with the regulation signal. An output current of a transconductance amplifier is limited with the variable current source to limit the first current in response thereto.