Multi-Stage High-Side Driver for Smaller Charge Pump Capacitors
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Solution Overview
Problem
Conventional power converters require large capacitors to ensure successful turning on of the high-side switch due to significant voltage drops when switching from off to on, occupying excessive space.
Innovation Solution
A multi-stage high-side driving mechanism is implemented, where the high-side driving circuit pulls up the control terminal voltage in stages, using the input voltage signal initially and then the charge pump, allowing for normal operation of the high-side switch with smaller capacitance capacitors in the charge pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large capacitance capacitors are used in the charge pump to supply high charging voltage to the control terminal of the high-side switch, then the high-side switch can be turned on successfully, but the capacitors occupy a large space in the power converter
Solution Approach 1:
The voltage boosting process is segmented into two stages: first stage uses the input voltage signal to pull up the control terminal voltage to an intermediate level, and the second stage uses the charge pump to boost it to the target voltage. This segmentation allows the charge pump capacitors to only handle the voltage difference from the intermediate level to target voltage, reducing their required capacitance and occupied space.
Solution Approach 2:
The first stage high-side driving signal performs a preliminary action by pre-charging the control terminal of the high-side switch to an intermediate voltage level before the charge pump operates. This preliminary action reduces the voltage swing that the charge pump capacitors must handle, allowing them to be smaller in capacitance and occupy less space.
2Reliability
If the charge pump directly supplies charging voltage from zero to target voltage when the high-side switch turns on, then the high-side switch can be turned on successfully, but the voltage drop causes the high-side switch to fail turning on
Solution Approach 1:
The charging process is divided into two segments: the first stage provides initial voltage boosting from zero to an intermediate level, and the second stage provides the remaining voltage boost to the target level. This segmentation ensures that at any point during switching, the control terminal receives sufficient voltage to maintain proper operation of the high-side switch.
Solution Approach 2:
The first stage driving circuit performs a preliminary voltage boost action before the charge pump operates. This preliminary action ensures that the control terminal already has a elevated voltage level when the high-side switch needs to turn on, preventing voltage drop issues and ensuring reliable switching operation.
Data Source
AI summary
A power converter having a multi-stage high-side driving mechanism is provided. A control circuit outputs a first high-side control signal. A high-side driving circuit, according to the first high-side control signal and a first input voltage signal, outputs a first stage high-side driving signal to a control terminal of a high-side switch. As a result, a voltage of the control terminal of the high-side switch is pulled up to a first stage voltage from zero. Then, the control circuit outputs a second high-side control signal. A charge pump outputs a charging signal. The high-side driving circuit, according to the second high-side control signal and the charging signal, outputs a second stage high-side driving signal to the control terminal of the high-side switch. As a result, the voltage of the control terminal of the high-side switch is pulled up from the first stage voltage to a target voltage.