SMART TECH & IOT
device battery protection devices, such as GLF Integrated Power’s GLF73xxx series products shown in Figure 3, to provide both overcharge and overdischarge protection. When a battery is charged past the overvoltage detection level, the IC’s charging switch opens at a preset delay time. If battery voltage decreases below its overdischarge level, the switch cuts off the battery’s power rail, resulting in ultra-low battery consumption. And when the load current reaches the short-circuit protection level, the IC switches and remains off to avoid potential system damage. The short circuit delay time also prevents false triggers that might open the switch.
Key Advantages of Advanced Smart IoT Battery-Protection
Figure 3: Advanced integrated power switch and battery-protection system
current drawing during short-circuit conditions. Figure 2 describes a traditional portable battery-protection system. It utilises discrete N-channel power MOSFETs and a separate control chip to handle large current and power requirements. In Figure 2, even though one of battery positive or negative terminals is disconnected from the load, the battery
remains connected across the VCC and VSS pins of the control circuit thereby constantly drawing current.
New Approach to ultra-Portable Battery-Protection Systems
The latest ultra-portable smart IoT devices for the consumer, medical device, industrial, asset tracking and other evolving electronic markets, are using different types of batteries that deliver signifi cantly less current to the device. These ultra-portable battery systems require ultra-low current consumption to extend the useful life of the device before needing to be recharged.
A new type of battery-protection system has been developed to meet the need for extended battery life in ultra-portable devices. The completely integrated power switch and battery-protection system, as shown in Figure 3, draws 1 µA -2µA during its
Figure 4: The fi gure 4 shows the moment when a battery cell is attached to the traditional battery pro- tection system in Figure 2. When a battery cell is attached, the battery pack supplies power to system immediately
operating mode and < 10nA leakage current when the device turns off.
This new approach utilises an ultra-low leakage P-channel MOSFET as the main switch element operating in series with the positive terminal of the battery and directly monitoring the load current through the switch.
Essential to this approach is using the industry’s most advanced smart IoT
connected medical devices, and other size constrained applications.
Three benefi cial characteristics of this new design approach:
1) This new battery protection system is very simple to use with almost no extra components, therefore reducing board space and manufacturing costs. It can be ready to work after a battery cell is attached.
APRIL 2024 | ELECTRONICS FOR ENGINEERS 33
The key advantage of this integrated battery-protection approach is that the battery on the input side can be completely protected through the high-side switch both from over discharging, as well as from overcharging by having the battery charger connected on the switch output side. As a result, this battery-protection system reduces component count and saves a signifi cant amount of space. This new IC with the accurate protection is in 1 mm x 1 mm WLCSP package. Its compact form factor makes it ideal for advanced wearables,
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