National Semiconductor Corporation

Barry James Culpepper

Kwok-Fu Chiu

Michael Jon Wurtz

Faruk Jose Nome Silva

Michael Eugene Broach

Hidehiko Suzuki

Chunping Song

Jeff Lee Nilles

A synchronous switching voltage regulator circuit is provided. After the first PWM pulse or at the end of a soft-start, a gradual transition is made from asynchronous rectification to fully synchronous rectification. The gradual transition to synchronous rectification is made by gradually increasing the time that the synchronous switch is enabled to be on.

Apparatus and method for start-up for a synchronous switching regulator

A hysteretic regulator is provided. The hysteretic regulator includes a delay compensation circuit that adds a delay to the output of the hysteretic comparator. The delay is dependent on the input voltage. For low duty cycles, the slope of the inductor current is much greater for the rising edge than it is for the falling edge. The delay compensation circuit adds sufficient delay to the falling edge so that the undershoot cancels the overshoot.

Apparatus and method for switching regulator with compensation delay for output voltage error correction

A controller for a synchronous switching regulator is arranged to control a switch with a control signal, and to control a synchronous switch with a synchronous switch control signal. The controller disables the synchronous switch control signal at power-up so that the regulator operates with asynchronous rectification. Also, the controller is arranged to detect whether the regulator is in discontinuous or continuous conduction mode by determining whether a switch node voltage at the switch node a switch node stays negative. The regulator keeps operating with asynchronous rectification until the switch node voltage stays negative for the entire off period of the switch, which indicates the regulator is operating in continuous conduction mode. At this point, the controller enables assertion of the synchronous switch control signal, so that the regulator operates with synchronous rectification. The controller is arranged to enable the output voltage to rise monotonically when driving a prebiased load.

Apparatus and method for monotonic start up of a synchronous switching regulator

Optimization of a parameter can be achieved by a servo loop having a temperature sensor, a temperature change detector, and a parameter adjuster. The temperature sensor monitors the temperature of an electronic device while the parameter is varied. The temperature change detector detects whether the electronic device temperature is increasing or decreasing. The parameter has a value associated with minimum power consumption when the monitored temperature reaches a minimum. The parameter is adjusted dynamically to a new preferred value as operating conditions of the electronic device change.

Apparatus and method for efficiency optimization of integrated circuits by temperature sensor and servo loop

A switching DC-to-DC converter having at least one power channel including an inductor and a controller which generates at least one power switch control signal for at least one power switch of each power channel. The converter is configured to operate in a continuous mode when the inductor current remains above zero, to enter a discontinuous pulse skipping mode of operation when the inductor current falls to zero (which occurs when the load current is below a threshold value), and to leave the discontinuous pulse skipping mode and resume continuous mode operation when the inductor current rises above zero. The main difference between the continuous and discontinuous pulse skipping modes is that in the continuous mode, a power switch has a duty cycle determined by a feedback signal indicative of the converter's output potential V (so that the duty cycle is independent of the current drawn from the converter by the load), and in the discontinuous pulse skipping mode the power switch has a duty cycle which is the longer of a minimum duty cycle and a discontinuous (non-pulse-skipping) mode duty cycle. The discontinuous pulse skipping mode is more efficient than the continuous mode under conditions of low load current. Preferably, the controller includes cycle-skipping circuitry operable in the discontinuous pulse skipping mode and optionally also the continuous mode to cause the power switch to remain off for at least one cycle under the condition that the converter's output potential rises above a threshold. Preferably, the cycle-skipping circuitry includes a comparator which compares an error amplifier output (indicative of the converter output potential) with a threshold potential, and logic circuitry (e.g., an AND gate coupled to the comparator output) which asserts a latch-clearing signal once per switching cycle when the comparator output indicates that the converter's output has risen above the threshold. Other aspects of the invention are a switching controller for use in such a converter and a method for generating power switch control signals for such a converter in a discontinuous pulse skipping mode of operation.

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Sunnyvale, CA, United States of America

Barry James Culpepper