Floating Bandgap Reference for Negative Voltage Clamping
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Solution Overview
Problem
High-side load switches face damage due to negative voltage pull when disconnecting from inductive loads, and existing clamping solutions suffer from large voltage variations and component size and cost issues.
Innovation Solution
The implementation of a floating bandgap reference and temperature compensation circuitry for accurate voltage clamping, using a resistor divider and amplifier to control voltage clamping values, enabling the use of lower breakdown voltage transistors and reducing switch size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional clamping solutions are used, then voltage clamping is provided, but voltage variations are large and component size increases
Solution Approach 1:
The patent changes the parameter of voltage reference from conventional fixed references to a floating bandgap reference that dynamically adjusts to negative output voltage conditions. This enables precise voltage clamping (improving measurement precision) while using standard transistor breakdown voltages rather than requiring oversized specialized components (reducing device complexity).
Solution Approach 2:
The patent introduces a floating bandgap reference as an intermediary element that mediates between the negative output voltage and the clamping circuit. This intermediary provides a stable reference voltage that enables precise clamping control without requiring large breakdown voltage transistors, thus improving precision while maintaining compact size.
2Reliability
If higher breakdown voltage transistors are used for clamping, then transistor damage is prevented, but switch size increases
Solution Approach 1:
The patent changes the operating parameter approach by using a floating reference that adapts to negative voltages, allowing standard breakdown voltage transistors to be used effectively. This maintains transistor protection (reliability) while avoiding the need for larger high-breakdown-voltage transistors (reducing switch size).
Solution Approach 2:
The patent makes the voltage reference dynamic rather than fixed, allowing it to track and adapt to negative output voltage conditions. This dynamic approach enables reliable transistor protection through active clamping control while using smaller, standard-voltage transistors instead of larger high-voltage devices.
3Measurement precision
If temperature compensation is not used, then circuit simplicity is maintained, but voltage clamping accuracy deteriorates under temperature variations
Solution Approach 1:
The patent compensates for temperature-induced parameter changes by introducing temperature compensation circuitry that adjusts the voltage reference in response to temperature variations. This maintains voltage clamping accuracy (measurement precision) while adding only moderate circuit complexity through standard compensation techniques.
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture for negative output voltage active clamping using a floating bandgap reference and temperature compensation are disclosed. An example load switch includes a floating bandgap reference circuit to generate a bandgap reference voltage. A resistor divider is to generate a resistor divider voltage. A temperature compensator to apply a temperature compensation current to the resistor divider to create a temperature compensated resistor divider voltage. A power transistor is to be enabled when the temperature compensated resistor divider voltage is less than the bandgap reference voltage. The example load switch can work under negative output voltage clamping and get better accuracy drain to source clamped voltage of power transistor for inductive load condition.