PD Controller IC with Staged Switch Drive for USB Slew Rate
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Solution Overview
Problem
Conventional power delivery (PD) controllers struggle to provide a high-level power switch control voltage using a general manufacturing process, as the voltage withstanding range of switch elements is less than the required swing range, necessitating a costly high-voltage manufacturing process.
Innovation Solution
A PD controller IC that generates a power switch control voltage and adjusts its level in stages during the power-on period to gradually turn on the power switch, allowing the use of a normal low-voltage manufacturing process while meeting the USB specification for slew rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a general manufacturing process is used for the PD controller, then manufacturing cost is reduced, but the controller cannot provide high-level power switch control voltage
Solution Approach 1:
The power switch control voltage is divided into multiple stages through sequential switching of first and second switches. The first switch connects the charge pump output to an intermediate node, and the second switch connects the intermediate node to the power switch control terminal, creating a staged voltage delivery mechanism that enables high voltage control using standard process components
Solution Approach 2:
An intermediate node is introduced between the charge pump circuit and the power switch control terminal. This intermediate node serves as a mediator that allows the controller to build up and deliver high voltage in a controlled manner, enabling standard process controllers to achieve high voltage output capability
2Speed
If the power switch is turned on quickly, then power delivery speed is improved, but the slew rate exceeds USB specification limits
Solution Approach 1:
The power switch control voltage is applied in a time-sequence manner through periodic switching actions. The controller first activates the first switch to charge the intermediate node, then activates the second switch to transfer the voltage to the power switch, creating a controlled temporal sequence that limits the rate of voltage change while still achieving rapid power delivery
Solution Approach 2:
The charge pump circuit pre-charges the intermediate node to the required voltage level before the power switch is activated. This preliminary voltage preparation allows the power switch to turn on rapidly once the control voltage is applied, achieving fast power delivery while maintaining compliance with slew rate specifications through the controlled charging sequence
Data Source
AI summary
A power delivery (PD) controller integrated circuit (IC) and a control method for a power switch are provided. A first terminal and a second terminal of the power switch are respectively coupled to a power pin of a universal serial bus (USB) connector and a power input terminal of a functional circuit. The PD controller IC generates a power switch control voltage to control the power switch. The PD controller IC may adjust a level of the power switch control voltage in stages during a power-on period of the functional circuit to gradually turn on the power switch.