Battery Power Management Circuit for Parasitic Diode Protection

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Solution Overview

Problem

Conventional power management circuits face safety risks when multiple batteries are connected in series, particularly due to the activation of parasitic diodes which can lead to heat generation and potential latch-up effects.

Innovation Solution

The proposed power management circuit includes a voltage conversion controller, a battery monitor, and a charger detector that dynamically control the operation of switches based on over-discharge signals and charger presence, preventing damage by ensuring the second switch is not turned off when the battery is over-discharged.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second switch is turned off during over-discharge protection, then the battery voltage is protected from dropping further, but parasitic diode activation occurs causing heat generation and potential latch-up effects

Engineering Contradiction:

Improvebattery protectionVSAvoidparasitic diode activation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of turning off the second switch during over-discharge protection, the patent inverts the conventional approach by turning on the second switch while turning off the first switch. This reversal prevents parasitic diode activation in the second switch while still achieving battery protection, eliminating the harmful thermal effects and latch-up risks associated with the conventional method.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent converts the potentially harmful situation of switch operation during over-discharge into a beneficial configuration. By strategically selecting which switch to turn off (first switch) and which to turn on (second switch), the patent transforms what would normally be a harmful parasitic diode activation into a safe operational state that maintains protection while avoiding thermal issues.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If the first switch is turned off during over-discharge, then parasitic diode activation is prevented, but the circuit configuration becomes complex requiring coordinated control of multiple switches

Engineering Contradiction:

Improveparasitic diode activationVSAvoidswitch control configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent simplifies the control logic by inverting the conventional switch operation strategy. Rather than attempting to keep both switches off or managing complex coordination, the patent establishes a clear inverted rule: turn off the first switch and turn on the second switch during over-discharge. This inversion creates a straightforward control algorithm that reduces computational complexity while maintaining effective protection.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If conventional over-discharge protection is implemented by turning off both switches, then battery protection is achieved, but load current flows through parasitic diode causing heat generation

Engineering Contradiction:

Improveover-discharge protectionVSAvoidheat generation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent inverts the conventional protection strategy of turning off both switches. Instead, it turns off only the first switch while turning on the second switch during over-discharge conditions. This inverted configuration maintains battery protection functionality while eliminating the parasitic diode conduction path that causes heat generation, thereby solving the thermal management issue.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent converts the harmful heat generation effect into a beneficial cool operation state. By strategically configuring the switch states (first switch off, second switch on), the patent eliminates parasitic diode conduction and its associated thermal problems, transforming a potentially dangerous thermal situation into a safe, cool operating condition while maintaining protection.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20250125638A1Power Management Circuit

Publication Date: 2025.04.17 WUXI ZGMICRO ELECTRONICS CO LTD

AI summary

Power management circuit comprises: positive and negative terminals coupled to a charger or load; a battery having first and second battery terminals, the second battery terminal coupled to the negative terminal; a charger detector coupled between the positive terminal and the first battery terminal; a voltage conversion controller and a battery monitor coupled to the battery, the battery monitor monitoring the battery's voltage during discharging, and sending out an over-discharge signal to the charger detector and the voltage conversion controller; a conversion output circuit, coupled to the battery, having first and second switches, and an inductor, the first battery terminal supplying electric current to the inductor via the first switch, and the negative terminal supplying electric current to the inductor via the second switch. Thus, the risk caused by a parasitic body diode of the second switch can be prevented when multiple batteries are connected in series.