DEMO MANUAL DC1568A LT3652EDD 2A Monolithic Multichemistry Battery Charger for Solar Power Description Demonstration circuit 1568A is a 2A monolithic multi- a sense resistor. A precondition feature trickle charges a chemistry battery charger for solar power applications low voltage battery, and bad battery detection provides a featuring the LT3652EDD. The LT3652 is a complete signal if the battery does not respond to preconditioning. mid-power Li-Ion battery charger that can operate over The LT3652EDD is available in a 12-lead (3mm 3mm) a wide input voltage range. The charger employs a 3.3V DFN surface mount package with an exposed pad. float voltage feedback reference that allows the battery Design files for this circuit board are available at float voltage to be adjusted up to 14.4V. The LT3652 has DEMO MANUAL DC1568A o perating p maximum charging current to the full programmed value. Once charging is terminated and the LT3652 is not actively DC1568A programs the output voltage to be 8.2V, and the charging, the IC automatically enters a low current standby 5.7V precondition threshold is internally set as a fraction mode where supply bias currents are reduced to < 100A. of the programmed output voltage. If the battery voltage drops 2.5% from the full charge float voltage, the LT3652 engages an automatic charge cycle The LT3652 can use a charge current based C/10 ter- restart. The IC also automatically restarts a new charge mination scheme, which ends a charge cycle when the cycle after a bad battery fault once the failed battery is battery charge current falls to one-tenth the programmed removed and replaced with another battery. maximum charge current. The LT3652 also contains an internal charge cycle control timer, for timer-based termina- The LT3652 includes provisions for a battery tempera- tion. When using the internal timer, the IC combines C/10 ture monitoring circuit. This feature monitors battery detection with a programmable time constraint, during temperature during the charging cycle using a thermistor, which the charging cycle can continue beyond the C/10 and suspends charging and signals a fault condition if the level to top off a battery. The charge cycle terminates battery temperature moves outside a safe charging range when a specific time elapses, typically three hours. When of 0C to 50C. the timer based scheme is used, the IC also supports bad The LT3652 contains two digital open collector outputs, battery detection, which triggers a system fault if a battery which provide charger status and signal fault conditions. stays in precondition mode for more than one-eighth of These binary coded pins signal battery charging, standby the total charge cycle time. or shutdown modes, battery temperature faults and bad battery faults. Quick s tart p D DC1568A is easy to set up to evaluate the performance 4. Increase PS2 until V is 7.2V. Verify that the input BAT of the LT3652EDD. current, I , is between 1.3A and 1.7A, the battery cur- IN rent, I , is between 1.775A and 2.225A and that the BAT Using short twisted-pair leads for any power connections, CHRG LED is on. with all loads and power supplies off, refer to Figure 1 for the proper measurement and equipment setup. 5. Increase PS2 until V is 8.5V. Verify that the battery BAT charging current, I , is less than 5mA and that the BAT Follow the procedure below: CHRG LED is off. 1. Jumper and power supply settings: 6. Decrease PS2 until V is 7.8V. Verify that the battery BAT JP1 = 1 JP4 = 1 current, I , is between 1.775A and 2.225A and that BAT the CHRG LED is on. JP2 = 1 PS1 = OFF 7. Set JP1 to 0. Verify that the charging current, IBAT, is JP3 = C/10 PS2 = OFF less than 5mA and that the FAULT LED and the CHRG 2. Turn on PS2 and slowly increase the voltage until V BAT LED are off. is 5.4V while monitoring the current into the BAT pin. 8. Set JP1 to 1. Connect a jumper from the NTC pin to If the current is less than 5mA, turn on PS1. Increase ground. Verify that the charging current, IBAT, is less PS1 until V is 12V while monitoring the input current. IN than 5mA and that the FAULT LED and the CHRG LED 3. Verify that the battery charging current, I , is between BAT are on. 250mA and 350mA. The CHRG LED should be on and the FAULT LED should be off. dc1568afa 2 ure roce rinciples