QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 763 650MA STANDALONE LI-ION BATTERY CHARGER LTC4065EDC DESCRIPTION Demonstration circuit DC763 is a complete constant- bling the charger (JP1). Placing the jumper to OFF current, constant-voltage battery charger designed to turns off the charger and jumper to ON enables the charge single-cell lithium-ion batteries. DC763 is charger. The full-featured DC763 also includes auto- based on the LTC4065 that is available in a 2mm matic recharge, lowbattery charge conditioning 2mm DFN package featuring an exposed bottom-side (trickle charging), soft-start (to limit inrush current) metal pad for soldering to the PC board. The LTC4065 and a C/10 charge LED indicator. Small surface features an internal MOSFET with thermal feedback mount components are used to minimize board space loop that regulates the charge current to limit the die and height. temperature during high power operation or high am- Design files for this circuit board are available. Call bient thermal conditions. The preset float voltage is the LTC factory. 4.2V with 0.6% accuracy and the constant charge LT is a registered trademark of Linear Technology Corporation current is 650mA. The DC763 has a jumper for ena- Table 1. Performance Summary PARAMETER CONDITION VALUE Input Voltage 3.75-5.25V IBAT (constant current mode) Vin=5V, Vbat=3.6V 650mA +/-5% Float Voltage Vin=5V 4.20V +/-0.6% Trickle Charge Threshold 2.9V +/-0.15V I (trickle current mode) 65mA +/-20mA BAT QUICK START PROCEDURE Demonstration circuit DC763 is easy to set up to charge current should be approximately evaluate the performance of the LTC4065. Refer to 65mA. This is the trickle charge mode for a Figure 1. for proper measurement equipment setup deeply discharged battery. Typically, a bat- and follow the procedure below: tery that has not been charged for a long time. 1. Set jumper JP1 to the ON position. Adjust 5. Starting from 0V, slowly increase the battery the output voltage of the input power supply simulator power supply (VBAT), observing the to 0V and then connect the power supply to chargers output voltage on the DVM. When the Vin and GND pins of the demo board. the chargers output voltage exceeds ap- proximately 2.9V, the charger will enter the 2. Set the battery simulator to 0V, and then con- Constant Current mode of the charge cycle nect it to the BAT and GND pins. with the charge current (IBAT) increased to 3. Connect the digital voltmeters as shown in the the programmed value of approximately setup diagram to measure the input voltage 650mA. This is the Constant Current mode. VIN, charger voltage (VBAT) and the charge 6. Continue to slowly increase the battery simu- current (IBAT). lator power supply, thus simulating a battery 4. Begin increasing the input voltage to 5V and accepting charge. The charge current should keep the battery simulator power supply at remain at the programmed value of 650mA 0V. The CHRG LED should be on, and the until the charger output voltage is within 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 763 650MA STANDALONE LI-ION BATTERY CHARGER 10mV of the preset voltage, at which time the and a new charge cycle begins. This is the charge current will begin to decrease. This is Recharge Threshold Voltage. the beginning of the Constant Voltage mode 8. To verify the shutdown mode, move jumper of the charge cycle. Continue to slowly in- JP1 to the OFF position. This shuts the crease the battery simulator power supply charger down dropping the charge current to while observing the CHRG LED to go out 0mA. when the charge current drops to approxi- 9. To verify battery drain current, remove the in- mately 10% of the programmed charge cur- put supply voltage. The ammeter that was rent. reading charge current now reads the battery 7. After the timer has timed out, slowly decrease drain current. A typical value is less than 1A. the battery simulator power supply. At ap- . proximately 4.1V, the charge current resumes 2