Application information

is high enough to withstand the largest battery or charger output voltage. In most cases, this will allow the 20V MOSFET switch in the charger path, and the main power path is used to use the 30V switch. The surge current detection resistor, the RSENSE small value sensing resistor (current diversion) is paired by measuring and restricting flowing through the pouring switch. It should be noted that the excitation surge restriction circuit aims to provide short -circuit protection; however, the design is designed to limit the packaging of capacitors and battery power switching conversion periods that restrict inflows or large -capacity. The maximum DC/DC input current required to be set at about 2 × or 3 × should be set at this excitation surge limit. For example, if the DC/DC converter is 2A, the excitation surge is limited to 6A by selecting a sensor RSENSE of 0.033

Note that the voltage on the resistance is only 66 millivol to fall under normal working conditions. Therefore, the power small (132MW) and 1/4W surface -consuming resistance consumed in the resistor can be used for this application. Some small values, the surface stickers are designed and applied for high -efficiency current influenza.

DC input monitoring resistor division

DCDIV input continuous monitoring DC power supply through dual -resistance compressor network, RDC1 and RDC2, as shown in Figure 5 Show. The threshold voltage DC comparator rises at 1.215V input voltage when power supply. Provide a lag current of about -35mV to ensure that the switch of the comparator is clean when the DC power supply voltage is reduced. Reduce comparators with good errors caused by DC input bias current. Set RDC1 12.1K so that when needed, 100μA flows through the resistor separator to reach the threshold. Then according to the following formula:

Battery monitoring resistor division

Connect two batteries from the battery input control to connect to the VBAT pin, so the connection is connected The top is shown in Figure 6. The threshold voltage of this low battery comparator is 1.215V when the battery voltage drops. About+35MV provides magnetic stagnation to ensure that when the battery voltage rises again. Try to minimize the low error battery comparator of the input bias current, assuming RB1 121K, so the threshold is reached. RB2 According to the following formulas:

VGG regulator electrical sensor and capacitor

The power supply voltage provided by the VGG regulator is significantly higher than any of the three main power supply. A voltage switch that controls the n guts MOSFET. The 36.5V micro -power booster regulator consists of three main power supply to achieve the maximum regulator efficiency. Because three input power diode and regulator

built -in output diode, onlyThere are three external VGG regulators require components: L1, C1, and C2, as shown in Figure 7. L1 is a small, low -current 1mh surface installation of electromators. C1 provides filtering at the top of the 1MH switch and should be 1 μF to filter the switch transient. The VGG output capacitor C2 is VGG output, which should be 1 μF and the rated voltage is 50V. C1 and C2 can be electric containers or ceramic capacitors. VCC and VCCP regulating capacitors VCCP logic power supply is about 5V, and provides power supply for most internal logic circuits. Wet the output with a 0.1 μF capacitor.

VCC power supply is about 3.60V, providing VGG switching regulator control circuit and gate driver. Wet the output capacitor with 2.2 μF 该. The capacitor is used for VCC's stability regulator output.

System -level precautions

The complete power management system LTC1479 is the heart of the complete power management system, which is responsible for switching the main power road recharger. Supporting power management μP provides a comprehensive control system for power management and LTC1479 and auxiliary power management systems. The typical dual -lithium -ion battery power management system is shown in Figure 8. If the good power supply is entered in DCIN (from the AC adapter), the switch is turned on for SW A/B, and the input of LTC1538-AUX DC/DC converter is provided for the current. The switching agency is disconnected from the switch, SW C/D, and SW E/F to block the current from the DC current back to the two battery packs. In this case, the LT1510 constant voltage/constant current (CC/CV) battery charger circuit is alternately used to charge two lithium ion battery packs. μP Decision by query which battery needs to charging the smart battery directly or through more indirect ways. After confirmation, the switch is switched to SWG or SW H, and opens it to pass the charger output current to 1 battery. At the same time, the selected battery voltage returns the voltage feedback of the LT1510 via LTC1479. After charging the first battery, charging from another pair of switches and the second battery after charging the charger circuit and the battery. The spare power supply provides the LT1304 circuit to ensure that the DC/DC input voltage will not decrease below 6 volts.

high -power DC/DC converter. As shown in Figure 9, the LT1304 monitoring input power supply voltage and activated when the voltage drops below 6 volt. DCIN and battery monitor and logic power supply LTC1479 subsequently increased the voltage regulator from the LT1304.

Charger system interface

LTC1479 is designed to directly use constant voltage (CV), constant current (CC) battery charger, such as as LT1510 and LT1511. LT1510 battery charger interface is shown in Figure 10. LT1510 CV/CC battery charger, from DCThe adapter input via the Schottky diode D1. The output of the charger points

Application information

Charging the battery with one of the N channel switches, SW G or SW H. The voltage of the rechargeable battery is connected to the top of the top parts, R4 and R5 to the top of the top of the LTC1479 to the charger voltage resistor at the same time, and for constant voltage charging. (See the LT1510 data table to learn more about more details.) The LT1511 battery charger interface LT1511, 3A CC/CV input current battery charger limit connection method and LT1510, as shown in Figure 11.

LT1511 has the third control loop to adjust the current from the AC adapter. Therefore, the input of DCLTC1479 and the host system via SWA/B, from the LT1511 adapter sensor sensor, RS4, is not directly from the DC input connector as the LT1510. This allows the host system to run a battery without overloading adapter at the same time. Reduce the current to keep the adapter current at the specified level. However, like the LT1510, the output of the LT1511 is charged to the R6 and R7 voltage of the R6 and R7 voltage of the charging battery H, charging battery voltage to the charging battery H, charging battery voltage. (For more information, see the LT1511 data table for detailed introduction of battery charging technology and application prompts.)

] CHGMON output capacitance load

In most applications, there is almost no capacitance load on the CHGMON output, only a simple resistor separator. It should be noted that the CHGMON output to the ground capacitor is less than 100. If more capacitors are needed, it may become a shield LobAT output display when charging. (BAT1 and BAT2 input and the internal resistance monitor switches between the input and charge may be output during the conversion periodIt may be that the error is interpreted by μP as insufficient battery battery. )

Power management microprocessor

and the LTC1479 interface LTC1479 can be regarded as it uses power management logic directly from μP, and changes under high current and the high voltage level in the power path Essence In addition, it directly provides μP with relevant AC adapters, battery and charging systems. LTC1479 logical input is compatible with TTL levels, and therefore, directly with the standard power management equipment μPS interface. In addition, due to the five logical inputs and two logical outputs, there is actually no delay between μP and LTC1479 (time delay). In this way, the μP can make a key type of time -type decision -making does not have the inherent delay related to the bus agreement, and so on. These delays in the power management system, but it is important that path switching control can be easily connected to μP through serial interface by direct connection to the power manager μP.

Select the power management microprocessor

The power management μP is the entire power system, and it is programmed as a customized requirement for each individual system. The power management μP must meet the requirements of the entire power management system, including the LTC1479 controller, the battery (and interface), and the backup system, charging system and host program. There are many cheap processors to choose from to meet these requirements.

Connecting the battery pack

LTC1479 design for almost any battery pack chemical or battery count. As long as the working voltage range of the battery pack is in 6V somewhere in 6V Between 28V. This allows system design. The low battery threshold can be set between 6V and 28V.

Traditional battery pack

Traditional battery packs do not include the battery interface system between the Smart battery pack and the host. Therefore, these battery packs usually only have three terminal sensors (thermistor) to the host system with three terminal sensors that connect batteries and temperatures. NTC THER MISTOR usually has a nominal resistor in the room for 10K temperature and is used to monitor the temperature of the battery pack. Lobat and DCINGOOD Filter/Filter a good approach is to add some good information cycles during low interest rates and DCIN transitions, such as when switching from a battery to DC power when switching the charger from a battery. This technology will eliminate error triggering related μP I/O (please remember that the 3-diode mode may be used during the uncertain period to eliminate instantaneous DCIN and battery status information.)

Intelligent battery pack

Smart battery pack, with smart battery compatibility system specifications, has a five -terminal connector. The negative and positive connection of the two -terminal to the battery. The third terminal is connected to the resistor in the thermistor lithium -ion battery pack in the nickel -cadmium and nickel -hydride battery packEssenceThe SMBDATA and SMBCLK lines in the Fourth and Fifth Terminal Connect to the Intelligent Management Bus (SMBU) integrated circuit are in the battery pack.

Application help

Linear technology application engineer LT1511 charger IC smart battery charger.Contact the factory, seek application help, and develop a complete smart battery system using LTC1479 for PowerPath control.