Charge-Pump Control Circuit for Battery Gate Voltage Regulation
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Solution Overview
Problem
Conventional battery control circuits fail to maintain the gate voltage of charging and discharging transistors at a predetermined level due to impedance variations in protective elements, leading to inadequate charging or discharging currents.
Innovation Solution
A charge-pump control circuit that includes separate drivers for charging and discharging transistors, with an oscillator and drive control circuit to set a control target voltage and adjust the clock frequency based on the lower of the two gate voltages, ensuring the gate voltage of the transistor with lower impedance reaches the predetermined level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single oscillator generates clock for both charge pump circuits, then device complexity is reduced, but manufacturing precision deteriorates due to process variation causing impedance differences in protective elements
Solution Approach 1:
The patent divides the single oscillator into two separate oscillators, one dedicated to each charge pump circuit. This segmentation allows each oscillator to independently control its respective charge pump, compensating for impedance variations in protective elements and ensuring both gate voltages reach the predetermined level despite manufacturing variations.
2Reliability
If protective elements are added to prevent dielectric breakdown, then reliability is improved, but manufacturing precision deteriorates due to impedance variation in protective elements
Solution Approach 1:
The patent applies different control strategies to each charge pump circuit based on their individual protective element characteristics. By providing separate oscillators and independent control, each charge pump can be optimized for its specific impedance conditions, allowing protective elements to function reliably without compromising gate voltage precision.
3Device complexity
If combined sense currents are used to generate clock frequency, then device complexity is reduced, but manufacturing precision deteriorates due to averaged current not reflecting individual transistor requirements
Solution Approach 1:
The patent segments the combined sense current approach into separate sense current paths for each charge pump circuit. Each sense current independently controls its dedicated oscillator, eliminating the averaging effect that caused gate voltage inaccuracy while maintaining reasonable device complexity through modular design.
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 ensures consistent and necessary charging and discharging currents are supplied by maintaining the gate voltage of transistors above the threshold voltage, even with impedance differences in protective elements, and allows for power-saving by stopping clock generation when voltages exceed the threshold.
Implementation Method 1
The battery control device 1200 hence includes a charge-pump control circuit 1300 which controls each of charge pump circuits 910 and 1110. The charge pump circuit 910 boosts the gate voltage of the discharging transistor 218, and the charge pump circuit 1110 boosts the gate voltage of the charging transistor 216.
Implementation Method 2
a protective element (not illustrated) is typically provided between the source and gate of each of the charging transistor 216 and the discharging transistor 218 to prevent dielectric breakdown due to an excessive rise in gate voltage
Implementation Method 3
A V/I conversion circuit 1130 converts the gate voltage of the charging transistor 216 into a sense current and outputs the sense current to an oscillator 906 through the transistor 1106. A conversion circuit 904 converts the gate voltage of the discharging transistor 218 into a sense current and outputs the sense current to the oscillator 906 through the transistor 1106.
Implementation Method 4
The oscillator 906 adjusts the clock frequency to drive each of the charge pump circuits 910, 1110 according to a current obtained by combining the respective sense currents of the V/I conversion circuits 904 and 1130 to keep the gate voltage of each of the charging transistor 216 and the discharging transistor 218 at a predetermined voltage.
Data Source
AI summary
A charge-pump control circuit includes an oscillator which supplies a clock for driving a charge pump driver to supply a first gate voltage to a discharging transistor in order to control discharge from a battery, and driving a charge pump driver to supply a second gate voltage to a charging transistor in order to control charge to the battery, respectively; and a drive control circuit which sets a control target voltage as one of the first gate voltage and the second gate voltage having a lower voltage in order to control generation of the clock by the oscillator according to the control target voltage.