DC606A Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC606 LI-ION BATTERY CHARGER IN SOT-23 LTC4056-4.2 DESCRIPTION Demonstration circuit DC606 is single cell Li-Ion tions. A charge LED illuminates while the charger linear charger in a SOT-23. Charge rates as high is charging the battery. as 700mA can be achieved. The user is provided with two control jumpers to select between Design files for this circuit board are available. ON/OFF and 450mA/700mA charge rates. The Call the LTC factory. reduced charge rate is suitable for USB applica- Table 1. Performance Summary PARAMETER CONDITION VALUE Input Voltage 4.25V - 6.5V Iout 450mA selected Vbat=3.6V 450mA +- 7% Iout 700mA selected Vbat=3.6V 700mA +-7% Float Voltage Vin =5V 4.20v+-1% Trickle Charge Threshold V = 5V 2.9V +-0.05V IN Recharge Threshold Vin 5V 4.05V+-50mV OPERATING PRINCIPLES Demo DC606 is a simple single cell Li-Ion C/50 trickle current until the cell voltage reaches charger. The demo features the LTC4056-4.2 2.9V whereupon full charge current is applied. A charger IC. This charger implements a constant charge LED is provided that illuminates every time current, and constant voltage charge scheme. the charger is charging the battery. The peak Charge termination is based on a timer. A topping- charge current is jumper selectable at either off charge will be applied if the cell voltage falls to 700mA or 450mA. The 450mA rate is intended for 4.05V to insure long-term charge maintenance. USB applications. Deeply discharged cells are conditioned with a low QUICK START PROCEDURE Demonstration circuit 606 is easy to set up to 3. Connect the demo board to the battery simula- evaluate the performance of the LTC4056-4.2. Re- tor as shown in Figure 1. fer to Figure 1 for proper measurement equipment 4. Set the battery simulator voltage to zero, slowly setup and follow the procedure below: increase the input voltage. When the supply 1. Use the jumper provided to select the desired voltage exceeds 4.5V the charger should acti- charge rate 450mA or 700mA. Verify that the vate and the charge LED will illuminate. Charger Enable jumper is set to the ON posi- NOTE: Make sure that the input voltage does tion. not exceed 6.5V. 2. With power off, connect the meters and input 5. Note that so long as the battery voltage is under power supply as shown in Figure 1. the Trickle Charge threshold of 2.9V the charge 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC606 LI-ION BATTERY CHARGER IN SOT-23 current is about 2% of the selected charge cur- 8. Wait 3 hours. The LED will extinguish as the rent charger terminates. The termination timeout can be reduced to 18 minutes by substituting a 6. Increase the battery voltage to about 3V and 100nF cap for C2. note that the charge current has increased to the jumper programmed current, either 450 or 9. Now slowly decrease the battery voltage as the 700mA. This is the constant current region of battery voltage reaches about 4.05V, a new the charging cycle charging cycle should begin. 7. Continue to increase the battery voltage, as the 10. Place the Charger Enable jumper in the OFF battery voltage approaches the float voltage of position. Note that the battery current draw is 4.2V the charge current will begin to drop. This extremely low (approx 1uA) and that the supply is the constant voltage region of operation. current draw is low (approx 35uA). 2