QUICK START GUIDE FOR DC1140A LTC3567EUF: High Efficiency USB Power Manager Plus 1A 2 Buck-Boost Converter with I C Control DESCRIPTION L, LTC, Burst Mode, Bat-Track are registered trademarks of Linear Technology Corporation. Demonstration Circuit 1140A is a high efficiency USB PowerPath and SwitcherCAD are trademarks of Linear Technology Corporation. Other product Power/Li-Ion battery manager plus a 1A Buck-Boost names may be trademarks of the companies that manufacture the products. regulator. The LTC3567EUF is available in a 24-pin (4mm 4mm) QFN surface mount package. PERFORMANCE SUMMARY Specifications are at T = 25C A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VBUS Bus Input Voltage Range 4.35 5.5 V LDO3V3 3.3V LDO Output Voltage Range 3.1 3.4 V VBAT Battery Float Voltage Constant Voltage Mode 4.15 4.23 V I Battery Charge Current Constant Current Mode, R = 2.00k 485 515 mA BAT PROG VOUT1 Regulator 1 Output Voltage IOUT1 1000mA 3.15 3.45 V OPERATING PRINCIPLES The LTC3567EUF is a full featured USB Power Manager and Li-Ion battery charger with a 1A Buck-Boost DC/DC 2 Buck-Boost Regulator Efficiency regulator. The LTC3567EUF has an I C interface that al- lows adjustment of the Buck-Boost output voltage, oper- ating mode, and USB power management control. The Bat-Track battery charger pre-regulator ensures the charger operates at the highest possible efficiency. The LTC3567EUF is composed of 6 functional blocks, all working together: USB Power Manager, Pre-regulator, Battery Charger, Ideal Diode, 1A Buck-Boost DC/DC regu- 2 lator, and I C. USB Power Manager The USB Power Manager is used to manage the load that the LTC3567EUF system presents to the USB interface. The load current can be programmed by changing the CLPROG resistor (R2), and by setting the operating mode 2 to 1X, 5X or 10X with the I C interface. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1140A HIGH EFFICIENCY USB POWER MANAGER PLUS 1A BUCK-BOOST CONVERTER LTC3567EUF 2 Pre-Regulator I C Interface 2 The pre-regulator is a high efficiency buck regulator that The I C interface is a 100kHz, write only serial interface produces a voltage at VOUT equal to the battery voltage that allows control of the USB input current limit, battery plus 0.3V. By reducing the voltage across the charger to charger on/off, Buck-Boost regulator (VOUT1) on/off, 0.3V the dissipation in the charger is greatly reduced, as Buck-Boost regulator operating mode, and Buck-Boost compared with a linear charger. output voltage via an internal 4 bit DAC. Battery Charger The battery charger operates in constant current mode, VOUT1 until the battery voltage rises to approximately the FLOAT voltage, of 4.2V, and then the charger switches to con- EN1 stant voltage mode. The charge current is programmed by the PROG resistor (R3), and has been set to 500mA, on DC1140A, with a 2.00k resistor. The battery charger implements trickle charging, for initial battery voltages less than 2.85V. It also implements a charge termination timeout of 4 hours, and a bad cell charging timeout of 30 minutes. An NTC Figure 1. VOUT1 startup input is used to determine if the battery temperature is suitable for charging, too hot or too cold. The statuses of the charger, as well as any faults, are sig- naled with the CHRG pin. Ideal Diode The Ideal Diode block is composed of an internal Ideal IOUT1 = 100mA Diode implemented with an on die MOSFET, as well as a MOSFET gate driver that allows the use of a parallel ex- ternal MOSFET. When the voltage on VOUT drops more than 15mV below Figure 2. SWAB1 switching waveform the voltage at BAT, the Ideal Diode becomes active. This will happen when VBUS is not present, or the load on VOUT exceeds the power available from VBUS. 1A Buck-Boost DC/DC regulator The Buck-Boost DC/DC regulator provides a regulated IOUT1 = 100mA output that can be above and below the input voltage. The battery voltage will vary from VFLOAT (4.2V) to as low as 2.5V. The Buck-Boost regulator can supply a regulated 3.3V output over this entire battery voltage range. The Buck-Boost is implemented with a full H-bridge switch, and proprietary control algorithm. Figure3. SWCD1 switching waveform 2