QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC708 LITHIUM-ION LINEAR BATTERY CHARGER WITH THERMAL REGULATION LTC4064EMS-4.0 Demonstration circuit DC708 is a complete constant- No isolation diode or current sense resistor required. current, constant-voltage battery charger designed to C/10 Trickle charge for deeply discharged batteries charge one Lithium-Ion cell used in battery backup ap- Auto recharge when battery voltage drops below pre- plications or applications that require greatly increased set threshold cycle life at the expense of battery capacity. The LTC4064EMS-4.0 used on this demo circuit features an Input Power OK LED indicator (ACPR) internal P-channel power MOSFET with a unique thermal C/10 Charge LED indicator (CHRG) feedback loop that reduces the output current under high ambient temperature and/or high power dissipation Fault LED indicator for out of temp range (FAULT) conditions. This feature allows the charger to provide Small surface mount components are used to minimize higher charge currents under normal conditions and still board space and height with the circuitry occupying ap- provide safe charging under abnormal conditions such proximately 0.15 square inches of board space with a as high ambient temperature, high input voltage or low height of 0.054 inches (1.4mm). battery voltage. The IC is available in a 10-pin MSOP thermally enhanced package featuring an exposed bot- Table 1. Typical Demo Board Specifications tom-side metal pad for soldering to the PC board. Input Voltage Range V 4.25V to 7V (upper IN Other Features include: range limited by PC board dissipation) Preset float voltage of 4.0V1%. Output Voltage V (constant 4.0V 1% BAT Greatly increased cycle life when used for charging voltage mode) 4.1V or 4.2V batteries. Output Current I (constant 1 A 8%, 0.5A 8% BAT current mode) (se 1A and 0.5A Constant Current selected by a jumper. lected by jumper) Capable of charging directly from USB power. Current Monitor Output 1.5V5% Full Cur- rent 3-hour charge termination timer. This timer can be set Output Current I (trickle 100mA 20%, 50mA BAT for other time periods through a capacitor change. current mode) 20% For instance, you may want to use a much shorter pe- C/10 CHRG LED Threshold Level 100mA 25%. 50Ma riod (on the order of 30 seconds) when evaluating the 25% board with a battery simulator instead of a real Li-Ion Circuit Board Temperature in 60C to 70C battery. Thermal Feedback Mode Charge Current Monitor Output can be used for gas Trickle Charge Threshold 2.457V gauging. Voltage Manual Shutdown Battery Drain Current with <1A V Removed IN Low battery drain current when input supply is re- moved 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC708 LITHIUM-ION LINEAR BATTERY CHARGER WITH THERMAL REGULATION To save time, we recommend using a battery simulator 4. Set the battery simulator to 0V, and then connect it to (described in Table 2 and Figure 1) If an actual re- the BAT and GND pins. chargeable Li-Ion battery is used, keep the DC resistance 5. Connect the digital voltmeters as shown in the setup between the charger and the battery to a minimum, as diagram to measure VIN, V(current monitor), charge this will affect the charge current in the constant voltage voltage (VBAT) and the charge current (IBAT). mode. EVALUATION Table 2. Test Equipment Required for Demo Board Evaluation Lab Power supply for input power 0 to 7V, 1.2A Undervoltage Lockout Feature Digital voltmeter for measuring 3 1/2 digits Increase the input power supply to approximately input voltage (VIN) 3.8V (battery simulator power supply set for 0V). Digital voltmeter for measuring 4 1/2 digits, resolution to 1mV battery voltage (VBAT) The charger output voltage and charge current should Digital voltmeter for measuring 3 1/2 digits, resolution to 1mV be 0. All three LEDs should be off. The charger is in PROG pin voltage (current moni- shutdown due to the undervoltage lockout feature. tor) Digital voltmeter for measuring 100mV range Trickle Charge Current voltage across current sense resis- Increase the input voltage to 5V and keep the battery tor (IBAT) simulator power supply at 0V. 4.2V Rechargeable Li-Ion Cell or 600mA/Hr to 1.3A/Hr Battery Simulator The CHRG and ACPR LEDs should now be on, and the Battery Simulator Consists of: FAULT LED should be off. The charger output voltage (VBAT) should be approximately 240mV, and the Power supply with coarse and fine 0 to 5V, 2.5A charge current should be about 100mA (10mV on the output voltage adjust controls charge current DVM). This is the trickle charge mode Power resistor (preload for power 2W, 10W for a deeply discharged battery. Typically, a battery supply) that has not been charged for a long time. Current sense resistor for measur- 0.1W, 1%, 1W ing charge current Constant Current Charge Current sense resistor for measur- 1k, 1%, 0.5W Starting at 0V, slowly increase the battery simulator ing battery drain current power supply (VBAT), observing the chargers output voltage on the DVM. SETUP When the chargers output voltage exceeds approxi- Refer to Table 2 and Figure 1 for equipment require- mately 2.45V, the charger will suddenly enter the con- ments and proper setup. stant current portion of the charge cycle, resulting in 1. Set jumper JP1 to the RUN position (lower posi- an abrupt jump in the charge current to the pro- tion). grammed value of approximately 1.0A (100mV on the charge current DVM). This is constant current mode. 2. Set jumper JP2 to the lower position, which programs the constant charge current to 1A. Move jumper JP2 to the upper position (0.5A) to re- duce the charge current (IBAT) to 500mA, resulting in 3. Set the input power supply to 0V, and then connect it a reading of approximately 50mV on the charge cur- to the VIN and GND pins of the demo board. 2