Battery Pack Current Mirror Bypasses PMIC FET
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mobile computing devices face challenges in reducing the cost, size, and impedance of battery charging circuitry, as existing systems rely on a battery field effect transistor (FET) within the power management integrated circuit (PMIC) that consumes space, raises costs, and adds series resistance, reducing battery life and generating heat.
Innovation Solution
The solution involves reusing battery pack-side current and voltage sensing elements to eliminate or bypass the battery FET in the PMIC, using a current mirror and voltage sensor to capture and output current and voltage data to the PMIC for regulating the buck charger, thereby reducing impedance and saving space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery FET is used in the PMIC for charging path control, then battery charging protection and control are achieved, but impedance increases and power is lost
Solution Approach 1:
The patent extracts the battery FET from the PMIC charging path and relocates its functionality to the battery pack side. The battery pack includes protection circuitry with FETs (first FET and second FET arranged back-to-back) that perform the charging protection function, allowing the PMIC to eliminate the battery FET entirely. This extraction removes the impedance and power loss associated with the PMIC's battery FET while maintaining charging protection through the battery pack's protection circuitry.
2Adaptability or versatility
If a battery FET is included in the PMIC, then charging control functionality is provided, but device size and cost increase
Solution Approach 1:
The battery FET and its associated control logic are extracted from the PMIC and placed in the battery pack. The battery pack's protection circuitry now contains the first FET, second FET, and current mirror, which together provide the charging control functionality previously handled by the PMIC's battery FET. This extraction reduces the PMIC's area requirements while maintaining full charging control capability through the battery pack's protection circuitry.
3Loss of energy
If battery pack-side sensing elements are reused, then impedance and cost are reduced, but additional circuitry is required in the battery pack
Solution Approach 1:
The battery pack's protection circuitry is designed to perform multiple functions: the first FET and second FET arranged back-to-back provide both overcharge protection and current limiting, while the current mirror simultaneously senses charging current and provides feedback control. The voltage sensor and current mirror work together to regulate the buck charger. This multi-functionality allows the battery pack circuitry to compensate for the removed PMIC battery FET while actually reducing overall system impedance.
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 approach reduces impedance, leading to power savings, faster charging, less heat generation, and a more compact, cost-effective PMIC, while maintaining efficient battery management.
Implementation Method 1
a current mirror is coupled to a charge protection circuit in the battery pack to capture a sensed current
Implementation Method 2
a voltage sensor captures a voltage level for the charging path
Implementation Method 3
a buck charging circuit, a charge controller, and a battery field effect transistor (FET)
Data Source
AI summary
Systems and methods for reuse of battery pack-side current and voltage sensing are disclosed. By reusing elements within a battery pack, a battery field effect transistor (FET) within a power management integrated circuit (PMIC) may be eliminated or at least bypassed. In a first aspect, a current mirror is coupled to a charge protection circuit in the battery pack to capture a sensed current. Likewise, a voltage sensor captures a voltage level for a charging path. Current and voltage are output to the PMIC for use in regulating a buck charger. In a second aspect, current data and voltage data are collected and digitized before being sent to the PMIC for use in regulating the buck charger.