Boost DC/DC Converter Load Switch Control for Overvoltage Suppression
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Solution Overview
Problem
Boost DC/DC converters face challenges in preventing overvoltage and overcurrent issues, particularly when input voltage fluctuations exceed target levels, making it difficult to maintain stable output voltage and manage overcurrent situations effectively.
Innovation Solution
A control circuit comprising a pulse modulator, logic circuit, and load switch drive circuit, which includes a PMOS transistor, error amplifiers, and hysteresis threshold voltage settings, allows for switching between modes to stabilize output voltage and limit currents, preventing overvoltage and overcurrent by forming a linear regulator and implementing overcurrent protection mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the boost DC/DC converter is stopped, then power consumption is reduced, but voltage continues to be supplied to the load causing overcurrent
Solution Approach 1:
The load switch is dynamically controlled based on the operating state of the boost converter. When the converter stops, the load switch transitions from ON to OFF state, dynamically adjusting the circuit configuration to prevent overcurrent while maintaining low power consumption
Solution Approach 2:
The control circuit monitors the operating state of the boost converter and provides feedback control to the load switch. This feedback mechanism ensures the load switch is properly controlled based on converter status, preventing overcurrent when the converter stops
2Ease of operation
If the duty cycle minimum value is set, then switching control is simplified, but overcurrent cannot be reduced below minimum duty cycle
Solution Approach 1:
The load switch acts as an intermediary between the boost converter and the load. It provides an additional control layer that can independently limit current to the load, working in conjunction with the PWM duty cycle control to prevent overcurrent even when minimum duty cycle is enforced
3Power
If input voltage exceeds target level, then power supply capability is improved, but overvoltage and overcurrent occur in output line
Solution Approach 1:
The control circuit incorporates voltage feedback monitoring that detects when output voltage exceeds the target level. This feedback triggers appropriate control actions including adjusting the load switch state to prevent overvoltage and overcurrent conditions while maintaining power supply capability
Data Source
AI summary
A control circuit of a boost DC/DC converter including a high side transistor and a low side transistor, includes a pulse modulator including a first error amplifier that amplifies an error between a reference voltage and a feedback signal corresponding to an output voltage of the converter, the pulse modulator being configured to generate a pulse signal with a pulse modulated, a logic circuit that generates a high side control signal and a low side control signal, and a load switch drive circuit that drives a load switch that is a PMOS transistor connected between the high side transistor and a load. The load switch drive circuit can make a switch between a first mode for fully turning on the PMOS transistor and a second mode for supplying a drive voltage corresponding to the output signal of the first error amplifier to a gate of the PMOS transistor.