Freescale Semiconductor,inc.

Northrop Grumman Systems Corporation

Fairchild Semiconductor Corporation

Nxp Usa, Inc.

Victor K Lee

Bin Zhao

Jack Cornish

Andrew Kameya

Brian Horng

Kenneth C Kwok

Timothy T Hsia

Jan Krellner

Weizhuang Wayne Xin

Andrew M Kameya

One example includes a power supply system. The system includes a voltage-limit power regulator to generate an output voltage and an instantaneous overvoltage sensor configured to detect an overvoltage condition associated with the output voltage. The system further includes an overvoltage latch-off timer system configured to initiate a latch-off timer in response to detecting the overvoltage condition. The latch-off timer can be uninterrupted by an amplitude of the output voltage. The overvoltage latch-off timer system can further be configured to detect a persistent overvoltage fault in response to detecting the overvoltage condition after expiration of the latch-off timer. The overvoltage latch-off timer system can be configured to generate a fault signal to disable the voltage-limit power regulator in response to detecting the persistent overvoltage fault.

Output impedance and load independent latch-off timer for voltage-limit mode protection

A circuit includes a regulation module having a threshold input to receive a clamp threshold voltage and a feedback input to monitor a swing-limited output voltage. The regulation module generates a difference signal that indicates a difference between the clamp threshold voltage and the swing-limited output voltage. A current compensation module includes a clamp port and an input port. The clamp port to controls the swing-limited output voltage and the input port receives the difference signal. The clamp port generates an adjustment current to control the swing-limited output voltage based on the difference signal. An adjustment network receives an input voltage and the adjustment current from the clamp port. The adjustment current to generate a voltage across the adjustment network such that the swing-limited output voltage at the clamp port is adjusted within a voltage range of the input voltage.

Dynamic tracking regulator to protect radiation-hardened devices

A circuit includes a tracking control module that receives an input voltage and a dynamic reference voltage. The tracking control module generates a swing-limited output voltage to mitigate over-voltage swings of the input voltage. The tracking control module includes a bias tracker that receives the dynamic reference voltage and generates a reference tracking control signal that tracks voltage changes in the dynamic reference voltage. A swing-limiter receives the reference tracking control signal and the input voltage. The swing-limiter limits the magnitude of the received input voltage based on a threshold and adjusts the swing-limited output voltage in response to the reference tracking control signal.

Open-loop tracking control module to control input range swing for radiation-hardened devices

Generally, this disclosure provides methods and systems for improved startup for DC-DC converters that reduce input voltage droop, in-rush current and output voltage jumps. The system may include a power stage circuitry including a plurality of power segments coupled in parallel, the power stage circuitry is coupled between an input voltage and output stage circuitry and configured to deliver power to a load coupled to the output stage circuitry. The system may further include PWM and power stage controller circuitry configured to sequentially and progressively activate the plurality of power segments to limit an input in-rush current from the input voltage during a ramp up period and output voltage at the output stage circuitry.

Startup of DC-DC converters utilizing multiple power segments

In one general aspect, a power supply circuit can include a power stage configured to be coupled to a power source and configured to deliver an output voltage to a load circuit, and can include a comparator coupled to the power stage and configured to receive a reference voltage. The power supply circuit can also include a hysteresis control circuit configured to receive at least one of a feedback voltage or a reference voltage and configured to change a hysteresis of the comparator in response to the at least one of the feedback voltage or the reference voltage during a soft-start of the power supply circuit.

Apparatus and methods of soft-start in a hysteretic power converter

In one general aspect, an apparatus can include a controller, and a power stage coupled to the controller and configured to be coupled to a power source. The power stage is configured to deliver an output voltage to a load module in response to the controller. The apparatus also includes a reference voltage circuit coupled to the controller and configured to be grounded to a first ground voltage different from a second ground voltage associated with the load module.

Differential sensing for voltage control in a power supply circuit

A PWM generation module generates a PWM data signal used to control a light emitting diode (LED) driver for one or more strings of LEDs of a display device. The PWM data signal is synchronized with the frame boundaries of the video content being displayed. The PWM generation module can configure the PWM data signal such that a new PWM cycle is initiated at the start of each successive frame, and further whereby those PWM cycles that would be prematurely terminated at frame boundaries are instead driven at a constant reference level until the frame boundary. With this configuration, a substantially linear average light intensity can be achieved across frames, thereby reducing or eliminating display distortion that is often present in other PWM cycle synchronization techniques. The PWM generation module can use a self-learning process to make adjustments to the expected number of completeable PWM cycles per frame in response to dynamic changes in the frame rate, PWM frequency, or other related display parameters.

Frequency synthesis and synchronization for LED drivers

Disclosed are example techniques for frame-based power management in a light emitting diode (LED) system having a plurality of LED strings. A voltage source provides an output voltage to drive the LED strings. An LED driver generates a frame timing reference representative of the frame rate or display timing of a series of image frames to be displayed via the LED system. An update reference is generated from the frame timing reference. The LED driver monitors one or more operating parameters of the LED system. In response to update triggers marked by the update reference, the LED driver adjusts the output voltage of the voltage source based on the status of each of the one or more monitored operating parameters (either from the previous update period or determined in response to the update trigger), thereby synchronizing the updating of the output voltage to the frame rate (or a virtual approximation of the frame rate) of the video being displayed.

LED driver with frame-based dynamic power management

A pulse width modulation (PWM) frequency converter converts an input PWM signal to an output PWM signal having a different frequency while maintaining a substantially equal duty ratio. The PWM frequency converter samples the input PWM signal for a PWM cycle using a sampling clock. A filter module filters the resulting set of one or more PWM parameters to compensate for noise introduced by potential clock mismatch, clock jitter, ambient variations, and other non-deterministic issues, thereby generating filtered PWM parameters. The sampling employed by the filter module compares a difference between the one or more current PWM parameters and previous (or historical) PWM parameters from an earlier sampled PWM cycle to a predetermined change threshold in determining a filtered set of one or more PWM parameters. The filtered set of one or more PWM parameters then is used to generate one or more corresponding PWM cycles of the output signal.

Pulse width modulation frequency conversion

Techniques for dynamic headroom control in a light emitting diode (LED) system are disclosed. An output voltage is provided to drive a plurality of LED strings. A feedback controller monitors the tail voltages of the LED strings to identify the minimum tail voltage and adjusts the output voltage based on the lowest tail voltage. The LED strings grouped into subsets and the feedback controller is segmented such that, for a certain duration, a minimum tail voltage is determined for each subset. The minimum tail voltages of the subsets are used to determine the overall minimum tail voltage of the plurality of LED strings for the certain duration so as to control the output voltage in the following duration. The segments of the feedback controller can be implemented in separate integrated circuit (IC) packages, thereby facilitating adaptation to different numbers of LED strings by integrating the corresponding number of IC packages.

LED driver with segmented dynamic headroom control

A light emitting diode (LED) system implements a LED driver to drive a set of one or more LED strings. The LED driver includes a voltage source to provide an adjustable output voltage to a head end of each LED string of the set for a first duration and a second duration following the first duration. The LED driver further includes a feedback controller to control the voltage source to adjust the output voltage for the second duration based on a digital code value generated from a minimum tail voltage of one or more tail voltages of the set at a sample point of the first duration. The LED driver further includes a power controller to temporarily enable one or more components of the feedback controller for a sample period of the first duration, the sample period comprising the sample point.

LED driver with dynamic power management

A voltage source provides an output voltage to drive a plurality of light emitting diode (LED) strings. A LED driver adjusts the level of the output voltage so as to maintain the lowest tail voltage of the LED strings at or near a predetermined threshold voltage so as provide sufficient headroom voltages for current regulators for the LED strings. The LED driver operates in an operational mode and a calibration mode, which can be implemented in parallel with, or part of, the operational mode. During the calibration mode, the LED driver determines, for each LED string, a code value representative of the level of the output voltage necessary to maintain the tail voltage of the corresponding LED string at or near the predetermined threshold voltage. In the operational mode, the code values from the calibration mode are used to control the voltage source to provide an appropriate level for the output voltage.

LED driver with dynamic headroom control

Power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed. A voltage source provides an output voltage to drive a plurality of LED strings. An LED driver implements a feedback mechanism to monitor the tail voltages of the active LED strings to identify the minimum tail voltage and adjust the output voltage of the voltage source based on the lowest tail voltage. A loop calibration module of the LED driver calibrates the feedback mechanism of the LED driver based on a relationship between a digital code value used to generate a particular output voltage and another digital code value generated based on the minimum tail voltage resulting from the particular output voltage.

LED driver with feedback calibration

Power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed. A voltage source provides an output voltage to drive the LED strings. An LED driver monitors the tail voltages of the active LED strings to identify the minimum, or lowest, tail voltage and adjusts the output voltage of the voltage source based on the lowest tail voltage. The LED driver can adjust the output voltage so as to maintain the lowest tail voltage at or near a predetermined threshold voltage so as to ensure that the output voltage is sufficient to properly drive each active LED string with a regulated current in view of pulse width modulation (PWM) performance requirements without excessive power consumption.

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Irvine, CA, United States of America

Victor K Lee