Perfect combination of multiple functions to create a robust system design for linear chargers - News - Global IC Trade Starts Here.

As portable devices become more demanding, portable end users will continue to face challenges in terms of robustness and stability. The main difference between a certain type of product and other products is reflected in various harsh environments, and the stability, reliability and robustness of the equipment are different. The bq2406X product family features a unique input overvoltage protection, thermal regulation, and DTC functionality for a robust system design.

Modern portable devices are quite popular, and more and more A and portable media players have begun to use lithium-ion (Li-Ion) batteries. The high demand for such rechargeable batteries has prompted many third-party manufacturers to continuously develop accessories such as charging docks and charging adapters. Although such charging adapters are not expensive, their charging characteristics and protection functions are often inferior and reliable with the adapters produced by the original OEMs. If you keep the following features in mind during the charger-level design process, you can implement a robust system for all external AC adapters:

1. Suppress the protection of transient voltage peaks;

2. Unregulated adapters;

3. An example of a thermal management and fault protection product line that demonstrates a range of linear chargers designed to meet these requirements.

A wide variety of AC adapters

One of the major issues in today's portable system design is the need to accommodate a wide range of input power sources, such as AC adapters, USB cables, or on-board/no-load DC outputs. The introduction of adapters to the market at a low price has replaced expensive adapters manufactured by original equipment manufacturers (OEMs), which has led to the development of numerous manufacturers and the success of rechargeable portable devices. The most popular power supplies of this type, such as AC adapters, can usually be divided into two types according to their characteristics: voltage regulator adapters (original accessories) and unregulated adapters (common accessory adapters).

The output voltage of the regulator adapter provides excellent line and load regulation through the internal circuitry. The output voltage provided by the non-regulated adapter is dependent on the load. The line load regulation capability is not strong, and the behavior of the adapter under overcurrent conditions is also different. Regulated adapters typically have a steeper transition region when entering an overcurrent region.

Input transient and overvoltage conditions

Today, portable devices powered by these adapters must be designed with integrated protection to minimize the risk of overvoltage damage to the terminal. Overvoltage can be in two modes: DC overvoltage and transient overvoltage.

Typically, DC overvoltage results from the wrong output voltage on the inserted accessory or non-standard adapter. On the other hand, when the adapter is hot-inserted into the terminal device, a transient overvoltage occurs. Transient overvoltage can easily reach twice the normal adapter output voltage, as shown in Figure 1.