lithium battery pack--- presented along Abstract: This application note presents to the lithium battery pack reader a complete Li-Ion battery pack solution supporting fuel gauging, charge control, battery protection, timekeeping, power management, and pack identification. All functionality is provided with three Dallas Semiconductor battery management components, namely the DS2770 lithium battery packbattery monitor and charge controller, DS2720 Li-Ion battery protection IC, and DS2415 real-time clock, along with supporting circuitry. The circuit diagram islithium battery pack presented along with details on each separate function.
With the addition of the DS2770 and DS2720 to the Dallas lithium battery pack Semiconductor product line, it is now possible to design an affordable cell pack that supports charge control, power control, fuel gauging, cell protection, time keeping, and pack identification. The circuit shown in Figure 1 is designed to accomplish all this by replacing an existing protection or protection/charge control circuit in a cell pack.
The Circuit
In Figure 1, the DS2720 is a protector for the cell, the DS2415 is a real-time clock (RTC), and the lithium battery pack DS2770 is a charge controller/fuel gauge. All three devices share a common ground, supply, and communication line. All external capacitors and resistors shown are for signal filtering and ESD lithium battery packprotection. The host device is powered from the PACK+ and PACK- pins on the left-hand side of the circuit. Communication to the pack takes place over the standard Dallas 1-Wire?nbsp;interface lithium battery pack labeled as DATA. The optional PS connection is an active low pack enable input designed to be connected to the system’s ON/OFF switch. The CHARGE SOURCE pin can handle an input of up to 15V that is current limited to the charge rating of the cell. The entire circuit draws less than 100�nbsp;typical when in active mode and less than 3�nbsp;typical when thelithium battery pack is disconnected.
|
