L, LTC, Burst Mode, Bat-Track are registered trademarks of Linear Technology Corporation.

Transcription

1 DEMO CIRCUIT DCA Quick Start Guide : High Efficiency USB Power Manager Plus A BuckBoost Converter DESCRIPTION Demonstration Circuit A is a high efficiency USB Power/LiIon battery manager plus a A BuckBoost regulator. The is available in a 4pin (4mm 4mm) QFN surface mount package. L, LTC, Burst Mode, BatTrack are registered trademarks of Linear Technology Corporation. PowerPath and SwitcherCAD are trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. PERFORMANCE SUMMARY Specifications are at T A = 5 C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V BUS Bus Input Voltage Range V V OUT Output Voltage Range Range is mode and load dependant V V BAT Output Float Voltage Constant voltage mode 4. V I BAT Output Charge Current Constant current mode 0.5 A BuckBoost Output Voltage.5.0 V IOUT BuckBoost Output Current A OPERATING PRINCIPLES The is a full featured USB Power Manager and LiIon battery charger with a A BuckBoost DC/DC regulator. The BatTrack battery charger preregulator ensures the charger operates at the highest possible efficiency. The is composed of 5 functional blocks, all working together: USB Power Manager, Preregulator, Battery Charger, Ideal Diode, and A BuckBoost DC/DC regulator. BuckBoost Regulator Efficiency USB Power Manager The USB Power Manager is used to manage the load that the system presents to the USB interface. The load current can be programmed by changing the CLPROG resistor (R), and by setting the operating mode to X, 5X or 0X with the ILIM, ILIM0 jumpers.

2 PreRegulator The preregulator is a high efficiency buck regulator that produces a voltage at equal to the battery voltage plus 0.V. By reducing the voltage across the charger to 0.V the dissipation in the charger is greatly reduced, as compared with a linear charger. The BuckBoost is implemented with a full Hbridge switch, and proprietary control algorithm. Battery Charger The battery charger operates in constant current mode, until the battery voltage rises to approximately the FLOAT voltage, of 4.V, and then the charger switches to constant voltage mode. The charge current is programmed by the PROG resistor (R), and has been set to 500mA, on DCA, with a.00kω resistor. The battery charger implements trickle charging, for initial battery voltages less than.85v. It also implements a charge termination timeout of 4 hours, and a bad cell charging timeout of 0 minutes. An NTC input is used to determine if the battery temperature is suitable for charging, too hot or too cold. The status of the charger, as well as any faults, are signaled with the CHRG pin. Ideal Diode The Ideal Diode block is composed of an internal Ideal Diode implemented with an on die MOSFET, as well as a MOSFET gate driver that allows the use of a parallel external MOSFET. When the voltage on drops more than 5mV below the voltage at BAT, the Ideal Diode becomes active. This will happen when is not present, or the load on exceeds the power available from. A BuckBoost DC/DC regulator The BuckBoost DC/DC regulator provides a regulated output that can be above and below the input voltage. The battery voltage will vary from VFLOAT (4.V) to as low as.5v. The BuckBoost regulator can supply a regulated.v output over this entire battery voltage range. EN Figure. startup IOUT = 00mA Figure. SWAB switching IOUT = 00mA Figure. SWCD waveform

3 APPLICATIONS INFORMATION The parasitic inductance in some USB cables may cause the VUSB voltage to overshoot at plug in. If this is the case it is recommended that the network of C,R and C be added to the board to damp out this overshoot. While, at first glance, it may appear that C C exceeds the USB specification for capacitive load on VUSB, in fact this is not the case. For most MLCC capacitors, with X7R/X5R dielectric the capacitance will be below 4.7μF, for DC biases of 5V. The battery charger must see low impedance to ground, which is the case when a battery is attached. In the event that a battery emulator is being used, or the impedance to ground is above 0.5Ω, the circuit of C5 and R80 is recommended. The BuckBoost regulator should be compensated with a Type III compensator, as shown on the schematic. The Buck, BuckBoost and pure Boost regions of operation have different poles/zeroes and PWM gains. In particular, the Buck Boost and pure Boost regions have a RHP zero, that must be accommodated. It is recommended that the stabilization be verified in all three regions of operation, with minimum and maximum load.

4 QUICK START PROCEDURE Using short twisted pair leads for any power connections and with all loads and power supplies off, refer to Figures 4 and 5 for the proper measurement and equipment setup. Follow the procedure below:. Set PS to 5V, and PS to.6v.. Observe I (AM). The USB input current limit is programmed for X (00mA), but the battery charge current is programmed to 500mA. So the USB input current limit is activated, and the charger cannot get enough current to charge at 500mA. Consequently, V CLPROG is at ~.5V, but V PROG cannot rise to V.. Set ILIM (JP) to HI and ILIM0 (JP) to HI. Observe I (AM). The USB input current limit is now 5X (500mA), and the charger can get enough current to charge the battery at 500mA. Consequently, V CLPROG is nearly.5v, and V PROG is at V. 4. Set ILIM (JP) to LO. Observe I (AM), V CLPROG (VM6) and V PROG (VM5). The USB input current limit is now 0X (A), and the charger can get enough current to charge the battery at 500mA. Consequently, V CLPROG is at 0.6V (0.5 *.5V), and V PROG is at V. 5. Set PS to 0V, and LOAD to A. Observe (VM) and V (BAT,OUT). Verify that.55v < <.60V, and (V BAT ) < 0.05V. The USB input voltage is off causing to fall. When falls to 5mV below V BAT, the LTC566 activates the ideal diode and supplies current to from the BAT pin. 6. Set LOAD to 400mA and PS to 5V. Observe (VM), V CLPROG (VM6) and V PROG (VM5). The USB input current limit is 0X (A), and the charger can get enough current to charge the battery at 500mA. In addition, is being loaded at 400mA, producing an aggregate load at of nearly 860mA. Consequently, V CLPROG is nearly.5v, and V PROG is at V. 7. Observe (VM) and (VM4). The BuckBoost regulator has been enabled at no load. The nominal output voltage on the BuckBoost regulator is.v. 8. Leave LOAD at 400mA, and set LOAD to 400mA. Observe (VM), (VM4) and V CLPROG (VM6). The USB input current limit is 0X (A), and the charger can get enough current to charge the battery at 500mA. In addition, is being loaded at 400mA, producing an aggregate load at of nearly 860mA. Consequently, V CLPROG is nearly.5v, and V PROG is at V. 9. Set CHRGEN (JP4) to HI. Set LOAD to A. Observe (VM), (VM4), and V CLPROG (VM6). The USB input current limit is 0X (A), and the charger is off. In addition, is being loaded at A, producing an aggregate load at of nearly 860mA. Consequently, V CLPROG is nearly.5v, and V PROG is at V. 0. Set LOAD to 0A, and CHRGEN (JP4) to LO. Set NTC (JP6) to EXT. CHRG LED should flash. The charger is now enabled, but the voltage is indicating that the battery temperature is very cold.. Set NTC (JP6) to INT and EN (JP) to ON. 4

5 VM AM LOAD 0V5V A PS 0V6V supply A AM VM AM VM.6Ω PS 0V5V supply A VM4 AM4 LOAD 0V5V A VM6 VM5 Figure 4. Proper Measurement Equipment Setup for DCA VIN Figure 5. Measuring Input or Output Ripple 5

6 0 4 EN JP EN CHRG 4 ILIM JP ILIM GATE HI JP ILIM0 JP4 CHRGEN L.uH LPS408MLC CLPROG E C6 0pF R 5k C4 0.uF 6V R5 00K R6 0 R7 0 R7 0 R k C uf 0V R 05k D GREEN CHGR R9.0 E5 LDOV.V 5mA E4 E.5V4.6V.5A E0.V A E9 E8 BAT VFLOAT=4.V 500mA E7 USB J TP C D D TP 0uF C D D 6V 0uF ID 4 TP ID 6V 5 U R.0 USBMINIB E 9 VIN LDOV L C.uH uf SW LPS408MLC OFF ON 6 8 LO LO LO JP5 MODE HI HI 8 ILIM0 CHRGEN MODE SWCD SWAB FB VC C7 0pF /0.5pF PROG E4 PWM BURST 5 CLPROG PROG INPUT CURRENT LIMIT SETTINGS ILIM ILIM0 CURRENT LIMIT mA (X) 0 A (0X) 0 SUSPEND (500uA) 500mA (5X) R.0k NTC BAT 9 NTC E5 JP6 NTC R4 00K Unless noted: Resistors: Ohms, 040, %, /6W Capacitors: uf, 040, 0%, 50V INT EXT OPT TP5 C8 pf C0 uf 0% R5 0 TP4 INJ R4 4k R6 k 060 Q SiDS C % R0.0 E E CHRG J BAT NTCEXT DFPDSA OPT E 4.5V5.5V R K E6 C9 uf 0% R8.0 Figure 6. DCA Schematic 6

7 Figure 7. DCA BOM 7