Consumer battery-powered handheld devices small, low-cost, as well as through the acceptance of a variety of input power to achieve the demand for ease of use of the system design engineer has brought many challenges. The use of battery PowerPath Manager series can be an effective solution to these challenges, it has to operate their own independent identity, to a wide range of power (such as car adapters, FireWire input, AC adapter, USB port and the battery itself) to switch seamlessly between the The implementation of efficient management.

For today’s battery-powered handheld devices the system design engineers, they face some major challenges, including minimizing power consumption to maximize efficiency, simplify design and reduce costs.

Many of today’s battery-powered portable electronic products from the AC adapter, car adapter, USB port or lithium-ion / polymer battery to obtain power. However, these different power between the power path for autonomous control of the management of the great technical challenge. All along, the designers are trying to adopt a “separation” approach to the completion of the function, that is, using a large number of MOSFET, operational amplifiers and other discrete components, but it encountered a system could trigger a major problem and the influx of hot-swappable Current problems, and so on. Recently, even the separation of IC solutions also require the use of multiple chips to achieve a practical solution, and integrated power management IC devices are easily able to solve these problems. In addition, IC autonomy to operate independently and also from the realization of an additional charge for the termination of the need for an external microprocessor, which further simplifies the design.

When used, such as FireWire, not the high-voltage regulator (> 5.5V) AC adapter and car adapter, the adapter voltage and handheld devices in the battery voltage difference between the very large. As a result, the linear charger may not be able to solve the problem of high power consumption, and the use of switch mode topology of the IC have been able to improve efficiency and reduce heat management problems. It is worth noting that when using USB, lithium-ion / polymer battery or the importation of lower than 5.5V power supply to the adapter, the linear charger / power management is a more appropriate choice.

PowerPath control

With PowerPath control device from the USB VBUS or AC adapter to power its own power supply, and single lithium-ion rechargeable batteries. In order to ensure a full battery charge in the bus when the connection has not been used in the state of the IC directly through the USB bus to the power load, rather than access to power from the battery. Once the power off, the current through an internal low loss ideal diode from the battery to the load flow, thus minimizing the pressure drop and power consumption.

PowerPath control features:

1. From the USB power supply, battery or AC adapter access to power;

2. To the OUT pin with a connected, as well as the application circuits with a BAT pin connected to the battery power transmission (assuming access to an external power supply rather than batteries);

3. Battery charge current will be adjusted to ensure that the charge current and load current and is no more than set the USB input current limit;

4. AC adapter current through an external device (such as power Schottky diode, or FET) connected to the output (load side);

5. Have a unique feature can be used by the AC adapter to provide power output in the electricity supply to the load for charging the battery at the same time;

6. OUT pin on the load to give priority to USB input current.

Ideal diode

When the output / load current exceeds the input current limit of input power or be removed, a low loss ideal diode from the battery to provide power. Through the ideal diode (rather than directly connected to a load cell) to enable the power supply to load a full battery charge in the external power supply to keep out before the full state of charge. Once the external power supply is removed, the output voltage drop, until the ideal diode forward bias was imposed so far. Plus there is bias toward the ideal diode battery will then provide power to the load. Ideal diode forward voltage drop much lower than traditional diode, and the reverse leakage current is also smaller. The small forward and power consumption reduced the pressure drop from the heat, thus extending battery life.

The article was first published at http://www.batteriesshop.co.uk/