Ideal diode has the following characteristics:

1. When the output / load current input current limit, or more than when the input power was removed, an ideal diode components from the battery to provide power;

2. Ideal diode (rather than directly connected to a battery load) load to the power supply to enable a full charge the battery in the external power supply was removed before the full charge to keep, and make the device even in a fully depleted The battery case was also able to work;

3. Once the external power supply is removed, the output voltage drop, until the ideal diode forward bias was imposed so far. Canada has been a positive bias will be followed by an ideal diode batteries to provide power to the load;

4. If the battery is the only available power supply or load current exceeds the input current limit has been set up, the battery will be laid in a BAT and the OUT pin between the ideal diode circuits automatically transfer power to the load;

5. Ideal diode (as well as the OUT pin on the recommendation of the capacitor) IC can be made without the use of a large body of the capacitor to deal with a large transient load and the AC adapter or USB VBUS connect / disconnect mode;

6. Low loss ideal diode by reducing power and the path of the IR drop extended battery run time.

Linear Technology’s power management devices to address the above-mentioned series of IC design problems. In this area, has two main features of the new product is the LTC4085 USB power management and high-voltage power LTC4089’s battery charger Manager

USB Power Manager - LTC4085

LTC4085 is a portable USB devices for the monolithic autonomous power manager, ideal diode controller and independent-linear battery charger. LTC4085 with PowerPath control feature from the USB VBUS or AC power adapter to power the system load, and single-cell lithium ion / polymer rechargeable batteries. With USB current limit specifications with, LTC4085 will be in the system load current increases automatically reduce the battery charge current. In order to ensure a full battery charge in the bus when the connection has not been used in the state of the IC through the USB bus to transfer power to the load, and the lack of access to power from the battery. Once the power has been removed, the current through an internal low loss ideal diode 200mΩ from the battery to the load flow, thus minimizing the pressure drop and power consumption. Provides for an optional external drive GATE PFET devices to connect the circuit board, so that the application needs to ideal diode impedance, the total fell below 30mΩ.

LTC4085’s unique features is the AC adapter can detect the access and use it as a system to load at the same time the power supply to charge the battery back-up power supply. LTC4085 also provides an AC adapter in the case of access to the value of higher than USB specifications allow (100/500mA) rating of (up to 1.5A) for the battery to charge for the option, which will be able to significantly To increase the speed of the battery charge. The total charge for the termination of the charging time by an external resistor to set up. When the charge current decreases, the charge cycle timer will automatically be extended to ensure that the batteries are always full state of charge. Additional features include automatic recharge, NTC thermistor input, AC adapter input is removed automatically switch to the battery, into current limit, reverse current isolation, and the heat adjustment Undervoltage closed.

LTC4085 floating voltage for the pre-4.2V, 0 ~ 85 ℃ temperature range to ensure the accuracy of 0.8 percent. Charge current can easily use a resistor to set up. For battery pre-charge and temperature appropriate certification will automatically to 10% of the current programming on the full discharge of the battery for trickle charge until the battery voltage exceeds 2.8V up. LTC4085 application circuit shown in Figure 1.

Like GPS navigation devices, PDA, digital cameras, digital photo reader, MP3/MP4 players, and other handheld devices, to provide USB and high input voltage battery charger as well as the ability to have many advantages, such as USB power so you do not have to have On the road to bring the convenience of travel charger installed, from a laptop or other PC with a USB port of your device for power supply equipment. Such as FireWire, 12 ~ 24V AC adapter or car adapter output on-board high-voltage power input can provide higher than the speed of USB charging, and allow in more places (such as motor vehicles), for charging, which is to improve Portable device one of the keys.

Convenience and high-power characteristics

LTC4089 and LTC4089-5 is a portable USB device’s own power manager, ideal diode controller and high-voltage-independent, high-efficiency battery charger. In order to achieve high efficiency charging, their switching topology can adapt to all kinds of input, including up to 36V (max 40V) high-voltage power supply (such as 12V AC adapter, car adapter and FireWire ports). In addition, they accept such as 5V and the USB adapter, and other low-voltage power supply. LTC4089-5 with PowerPath control feature from the bus, or USB AC adapter to power supply equipment, and equipment single lithium-ion rechargeable batteries, but also in a serious shortage of electricity or run out of battery case Under “immediate access” to operate. LTC4089 typical application circuit shown in Figure 2.

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