QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 735 LITHIUM-ION LINEAR BATTERY CHARGER WITH LDO REGULATOR LTC4063EDD DESCRIPTION Demonstration circuit 735 is a complete constant- regulator, monitoring charge current and program- current, constant-voltage battery charger for one ming the minimum charge current level for termina- tion (I ). An LED indicates when the charge cur- Lithium-Ion cell and includes a 3 Volt low dropout DETECT linear regulator. The LTC 4063EDD used on this rent has dropped below the minimum charge current demo circuit features an internal P-channel power termination level. MOSFET with a unique thermal feedback loop that The IC is available in a 10-pin (3X3) DFN thermally reduces the output current under high ambient tem- enhanced package featuring an exposed bottom-side perature and/or high power dissipation conditions. metal pad for soldering to the pc board. This feature allows the charger to provide higher charge currents under normal conditions and still provide safe charging under abnormal conditions such as high ambient temperature, high input voltage Design files for this circuit board are available. Call or low battery voltage. the LTC factory. Jumpers on the board allow charge currents from LTC is a registered trademark of Linear Technology Corporation 250mA to 1A to be programmed and several charge termination methods to be used. Terminals are pro- vided for shutting down the charger and/or the linear Table 1. Performance Summary (T = 25C) A Input Voltage Range V 4.3 to 8V (upper range limited by PC board dissipation) IN Input Undervoltage Lockout 3.8V Output Float Voltage V (constant voltage mode) 4.2V 0.5% BAT Output Current I (constant current mode) 1 A, 0.5A, 0.25A 8% (selected by jumpers) BAT Current Monitor Output 1V 5% Full Current Charge Termination Timer 3 Hours 10% 50mA, 25mA 10% Charge Termination Threshold Current (I ) DETECT Low Dropout Regulator Output Voltage 3.00V 5% Low Dropout Regulator Rated Output Current 100mA Input Voltage Range VIN 4.3 to 8V (upper range limited by PC board dissipation) Input Undervoltage Lockout 3.8V 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 735 LITHIUM-ION LINEAR BATTERY CHARGER WITH LDO REGULATOR OPERATION When minimum charge current termination (I ) DETECT DC735 allows three methods of charge termination is used, the charge cycle ends when the Charge cur- which are selected using jumper JP2. In the upper rent drops below the I level. The CHRG LED DETECT Timer position, the charge cycle terminates at the also goes off. end of the timer period as set by capacitor C2. The 3 hour timer is sufficient time to fully charge a depleted NOTE: The current monitor terminal can be used to battery when charging at a current level of C/2 to 1C. indicate charge current level at all times during the charge cycle with 1 Volt indicating 100% of the pro- The lower Iterm position selects minimum charge grammed current level. This terminal can also be current termination (I ). This method terminates DETECT used to program other charge currents by removing the charge cycle when the charge current drops to a jumper JP5 and connecting an external programming programmed threshold level after the battery has resistor from the current monitor pin to ground. See reached the constant voltage portion of the charge data sheet for details. cycle. Placing the jumper (JP3) in the middle position defeats the on board termination thus allowing exter- The charger can be evaluated using an actual Lithium nal user termination. Ion battery or a battery simulator. The battery simula- tor is faster because all battery state-of-charge condi- The charge current and the termination current are tions can be quickly simulated. selected using a combination of jumpers JP4 and JP5. (See table 2) Table 2. Jumper Positions for Charge Current and Termination QUICK START PROCEDURE Current. A battery simulator consists of an adjustable power Charge Current / Termination Current supply with a load resistor across the power supply ICHG Iterm Select (JP4) output. The resistor value is selected that will provide Select approximately 1A when the power supply is set for C/10 Fixed 50mA (JP5) 2.5V and the power supply must provide at least 1.7A when adjusted for 4.2V. For this battery simulator, a HIGH 500mA / 50mA 1A / 50mA 2.5 Ohm, 10 Watt power resistor connected to the LOW 250mA / 25mA 500mA / 50mA output of a 5V, 2A bench supply will work fine. The power supply can now sink and source current, simi- lar to a battery, and by changing the power supply The 3 Volt LDO Regulator is powered from the battery output voltage, any battery state-of-charge condition and requires approximately 2.6V to become active, can be quickly simulated. although the output will not be regulated until the bat- Begin circuit evaluation by moving the jumpers to the tery exceeds 3V. appropriate positions. JP1 and JP3 should be in the The CHRG LED always indicates the presence of ON position. Move the Termination Method jumper charge current that is greater than the I current DETECT (JP2) to the Iterm (lower) position to select minimum level that is selected by the Iterm jumper (JP4). The charge current termination. Move jumper JP4 to the LED is on for charge current greater than Iterm, re- 50mA (lower) position and JP5 to the HIGH (upper) gardless of the termination method used as set by position. The charger is now set to charge at 1A and jumper JP2. use minimum charge current (Iterm = 50mA) for charge termination. 2