Programmable Load Transient Circuit for Fast Slew Rate Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing load transient testing methods for power supplies are inefficient in achieving fast transient responses and pulse repetition frequencies due to inductive cable effects and require physical modifications, and conventional circuits depend on variable resistors that slow down validation tests.
Innovation Solution
A programmable load transient circuit using a switchable power device as a voltage-controlled current source with a feedback loop, including a current sense device and level shifter, allows for adjustable pulse signals or DC voltages to control the load current independently of the device under test's output voltage, enabling faster and more flexible testing across multiple voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an off-the-shelf electronic load is used for load transient testing, then the configuration of load step is easy, but the slew rate is limited due to cable inductance
Solution Approach 1:
The patent extracts the load transient generation function from a separate electronic load device and integrates it directly into the DUT output circuitry. By placing the load transient circuit at the output of the DUT, the cable inductance is eliminated, enabling fast slew rates while maintaining easy configuration through programmable control.
Solution Approach 2:
The patent introduces a programmable load transient circuit as an intermediary between the DUT and the measurement system. This intermediate circuit generates the load current step locally at the DUT output, avoiding the need for external cables and electronic loads, thus achieving both ease of configuration and high slew rate performance.
2Speed
If the power supply is physically bolted to the electronic load, then the maximum slew rate of the electronic load can be reached, but it is impractical for most transient load testing
Solution Approach 1:
The patent merges the load transient generation functionality directly into the DUT output stage by integrating the switchable power device and current source circuitry with the DUT. This consolidation eliminates the need for separate electronic load equipment and physical bolting, achieving maximum slew rate while maintaining practicality for routine testing.
Solution Approach 2:
The DUT essentially serves itself by incorporating the load transient generation capability within its own output circuitry. The programmable current source and switchable power device enable the DUT to generate its own load transient test signals, eliminating dependence on external equipment and complex physical connections.
3Speed
If a FET connected in series with a resistor is used for load transient circuit, then faster slew rates can be achieved, but the peak load current varies based on DUT output voltage requiring R value changes
Solution Approach 1:
The patent implements a programmable load transient circuit where the resistance value can be dynamically adjusted based on the DUT output voltage. The microcontroller monitors the voltage and programmably changes the resistance value to maintain constant peak load current across different voltage conditions, enabling fast slew rates without manual intervention.
Solution Approach 2:
The patent changes the resistance parameter programmably based on the operating conditions (DUT output voltage). By dynamically adjusting the resistance value according to the voltage level, the system maintains optimal peak current levels and slew rates across different operating points, eliminating the need for manual resistor changes and accelerating validation testing.
4Adaptability or versatility
If variable resistors are used in conventional load transient circuits, then different peak currents can be obtained, but test execution is slowed down
Solution Approach 1:
The patent replaces the mechanical variable resistor system with an electronically programmable resistance implementation. The microcontroller programmably controls the resistance value through digital means, eliminating the need for manual mechanical adjustment. This substitution maintains the adaptability to achieve different peak currents while dramatically increasing test execution speed through automated control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables faster and more efficient load transient testing by maintaining high slew rates and reducing test execution time, independent of the device under test's output voltage, and allows for automated testing across a wide range of frequencies and voltages without physical component replacement.
Implementation Method 1
The integrator provides an output drive voltage that is coupled to an input of a level shifter
Implementation Method 2
The level shifter provides an output waveform or DC voltage to the power device's control node that is a function of the IDavg
Data Source
AI summary
A programmable load transient circuit includes a switchable power device for coupling a DUT output to its non-control node in series with a current sense device. A feedback loop is between the current sense device and the power device's control node that includes an integrator including an amplifier coupled to receive a signal that is a function of an average load current (IDavg) supplied by the DUT from the current sense device and to receive a reference voltage (Vref). The integrator provides an output drive voltage that is coupled to an input of a level shifter which receives a pulse signal or DC level at another of its inputs. The level shifter provides an output waveform or DC voltage to the power device's control node that is a function of IDavg.