DC569B Analog Devices

DEMO MANUAL DC569B LTC4054-4.2 Li-Ion Battery Charger in SOT-23 Description Demonstration circuit 569 is a single cell Li-Ion linear The reduced charge rate is suitable for USB applications. charger in a SOT-23. Charge rates as high as 600mA can A charge LED illuminates while the charger is charging be achieved due to the LTC 4054s internal die temperature the battery. control loop that prevents excessive PCB heating under Design files for this circuit board are available at worst-case conditions. The user is provided with a control DEMO MANUAL DC569B Quick s tart p D Demonstration circuit 569 is easy to set up to evaluate Verify that the LTC4054-4.2 thermal loop is working the performance of the LTC4054-4.2. Refer to Figure 1 the charge current should decrease. Remove the iron for proper measurement equipment setup and follow the and the charge current increases. This demonstrates procedure below: the constant die temperature operating mode. 1. Use the jumper provided to select the desired charge 8. Continue to increase the battery voltage. Note that as rate 450mA or 600mA. the voltage drop across the LTC4054 decreases, the constant die temperature loop is no longer active and 2. With the power off, connect the input power supply to the charge current is the programmed charge current. V and GND. IN 9. Continue to increase the battery voltage as the bat- 3. Connect the demo board to the battery simulator as tery voltage approaches the float voltage of 4.2V, the shown in Figure 1. charge current begins to drop. Note that as the charge 4. Set the battery simulator voltage to zero and then slowly current drops to 10% of the programmed current, the raise the input voltage. charger terminates. Charge current falls to zero and the charge LED extinguishes. When the supply voltage exceeds 4.25V, the charger should activate and the charge LED will illuminate. 10. Slowly decrease the battery voltage to simulate a long term self-discharge of the battery. Note, that as the 5. Note that, so long as the battery voltage is under the battery voltage drops to 4.05V, that another charge Trickle Charge threshold of 2.9V, the charge current cycle is initiated. is 10% of the selected charge current. 11. Place the charge rate selector in the OFF position. Note 6. Increase the battery voltage to about 3V and note that that the battery current draw is extremely low (approx the charge current has increased beyond the trickle 1A). Also note that the supply current draw is low charge current. (approx 20A). 7. Heat up the LTC4054 by touching a soldering iron to the PCB. Figure 1. Proper Measurement Equipment Setup dc569bf 2 ure roce