Lithium battery management solution for portable equipment

　　Author ：Iflowpower – Portable Power Station Supplier

The importance of battery management has been self-evident. More and more products are moving toward portable directions, using an unprecedented independence. Before dozent years ago, the cordless phone first supplied the freedom of walking in the home.

Now, portable rechargeable products make people stay in contact with their families while people travel. More and more products use rechargeable batteries, and with the decrease of product volume, the complexity of these products is constantly improving. The charging battery itself is also changing, battery manufacturers strive to launch new products that adapt to rapidly changing markets.

The battery voltage is added, the shape specification is changed, and the energy density is also climbing. Consumers' understanding of the battery is also deeply in-depth, they have to have more flexible, longer working hours, lower cost and higher security. Microchip has been working hard to simplify system design with PIC microcontrollers for many years.

At present, Microchip is using this technology to the battery management product line to simplify and better manage the charging system. Method First, a typical battery management system is divided into four modules of charging, protection, electricity measurement, and safety: 1. The battery pack based on the secondary battery is different from a battery pack, and the secondary battery pack is charged after use.

Instead of being discarded like a battery. The types and charging algorithms of the charging circuit are varied, and they are appropriately charged for specific chemical types of batteries. The position of the charger should also be appropriately selected.

The charger is a stand-alone unit: is the direct charge of the converter or through the converter; the charger is integrated within the system or within the battery pack; other important considerations include charging time, temperature range and noise requirements. Microchip supplies a variety of charging management products for linear chargers of single or double lithium ion / polymer battery pack. The output noise of the linear charger is low, which is very important for those who send and receive voice and data.

Designed for high efficiency, PS200 switch mode charging controller up to 1MHz. It includes algorithm for charging of lithium ion batteries, nickel batteries and lead-acid batteries. Since the design of the switch charger is more complicated, Microchip has supplied software tools to guide designers to perform IC configuration and circuit diagrams.

For the standard industry supplied to the charger product, another solution is to use the electricity meter IC with a charging controller. The PS501 has a pulse charging circuit to control universal input / output, which can achieve this requirement. This topology supplies a very compact and cost-effective solution.

The charging portion of the system is separated, and Microchip has the desired algorithm to optimize charging, including maximizing charging capacity, shortening charging time, and makes customers achieve best satisfaction. 2. Protection When using a lithium ion / polymer battery, protection must be supplied because overcharge or overheating can cause fire or explosion.

Lead-acid batteries or nickel batteries do not need to be protected, but they are often supplied to protect circuitry to prevent battery damage or degradation. The main protection circuit is a dedicated circuit to detect whether an unsafe situation has occurred and the battery pack is turned off to prevent damage when detecting an unsafe situation. Secondary protection circuit prevents battery from continuing charging and / or discharge under unsafe status.

In the event of a failure of the main protection circuit, it can supply backup protection for the secondary circuit. The user can also add a new level of protection, such as chemical fuses, and chemical fuses can be permanently closed when the other level protection fails. Dedicated security IC is usually used for main protection circuitry.

With regard to secondary protection and stability protection circuits, battery management IC is ideal, because they do not add costs of solutions. MICORCHIP's electricity meter, such as PS501 and PS810, can monitor the voltage, battery pack voltage, current and temperature of each battery. Universal Input / Output (GPIO) pin has powerful configuration functions, setting up, and reset any possible electric quantitative conditions.

This flexibility allows the electricity meter to meet very complex safety requirements. 3. The amount of electricity metering is not only to monitor the current flowing out of the battery pack.

Accurate power metering should be a system method, comprehensively consider typical ways, environment and customer expectations. Ideally, the battery management IC can supply good working performance to the user, while supplying the required information to the system so that it makes intelligent selection to improve system performance. Intelligent electricity metering algorithms can extend system running time and battery life, and supply additional security by accurately detecting full charge and full discharge point.

They also detect and prevent battery imbalance and overheating. These algorithms can be adjusted according to system conditions and can slow down battery aging. They use the configurable model of battery behavior to ensure that the loss caused by self-discharge and charging correctly.

These algorithms can be customized by customers so that users only accept related information, but don't worry about accidental shutdown that can lead to data loss. Microchip's power meter has enhanced function, making power metering more reliable. System accident shutdown is one of the most unpleasant things when using portable devices, most people should feel the same.

It will reduce customer satisfaction, and it will cause significant data loss and time and money. Unexpected shutdown generally occurs when the battery voltage dropped to the support system below. When the load is added, the battery voltage will decrease, especially when the discharge line will end, the slope of the discharge curve is added.

In order to prevent accidental shutdown, Microchip uses an algorithm based on energy demand information when shutdown, as shown below. The power meter automatically selects the appropriate shutdown point to ensure that sufficient residual energy issues alert and saves data to the user. Over time, shutdown points will also change.

With the aging of the battery, the full capacity is lowered, the voltage of the discharge curve also changes. The aging algorithm can adjust the shutdown point to ensure that the energy will be wasted with battery aging. 4.

The system with the detachable battery pack should use safety measures to prevent the system works under the design of unreasonable battery. If the system adopts non-organized chemical cells, excessive or overlapping may cause unsafe states. If you do not use steady-state chemical cells in accordance with the manufacturer's requirements, it may result in a decrease in performance and shortened life.

The current simple mechanical barrier is currently used, such as a unique shape specification or connector, and a sign-read sign from the battery. But unfortunately, these security measures are easily broken. Users really want is a flexible system-level solution that ensures user security, improve system performance, and supply long-term reliability.

Microchip supplies a good solution for battery verification, KeeloQ°Encryption algorithm, this compressed 64-bit encoding algorithm can provide the Hardware of the KEELOQ algorithm for various applications supplied by the industry, host and peripherals. Today, the KeeloQ algorithm has been applied to various safety systems, such as key access control systems (important applications in the automotive industry). When using KeeloQ technology for battery verification, the system is a host, and the battery is peripheral.

The system stores the manufacturer code and a random number generator. When the battery is made, a unique serial number and key are generated and stored in memory, and will not be changed. When the battery is connected to the system, the system requests a serial number and sends a 32-bit champion.

The battery will supply the corresponding serial number and give a 32-bit response. Due to a wide variety of battery management systems, Microchip uses KeelOQ technology in its battery management products and many PIC microcontrollers. When using Microchip power timings in the battery pack, there is no need for additional hardware to make the system security function.

If there is no power meter in the battery pack, you can use the PIC microcontroller as a KeeloQ peripheral hardware. Host hardware supporting KeeloQ technology includes processors, electric quantitures, and chargers. .