QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC929A-A/B USB POWER SOLUTION IN DFN 6X3 LTC4089/-5 DESCRIPTION Demonstration circuit DC929A-A/B is a monolithic high termediate bus voltage topology that results in faster voltage (6V-36V) switching buck regulator, USB Power- charging and lower power loss than the charger fed to- 2 path controller, and Li-Ion battery charger. It is based pology. All this functionality consumes less than 2cm on the LTC4089/-5 and provides the following functions: of PCB area with all components on one side of the PCB. 1.2A monolithic buck regulator with output voltage Design files for this circuit board are available. Call tracking battery voltage V , a 700mA CC/CV timer ter- BAT the LTC factory. minated temperature qualified charger suitable for Li-Ion , LTC , LT, and Powerpath are registered trademarks of Linear Technology cells, a USB power manager that insures compliance Corporation. with the USB power specification and Powerpath man- agement for the battery. The LTC4089/-5 uses the in- Table 1. Performance Summary PARAMETER CONDITION VALUE HVIN Input Voltage 6V - 36V HVOUT/VOUT V = 6V - 36V = V +0.3V (for LTC4089) HVIN BAT = 5V (for LTC4089-5) Battery Charger I V = 5V, Vbat=3.6V 700mA +/- 7% BAT USB Float Voltage V = 5V, battery disconnected from BATT pin 4.20V +/- 35mV USB Trickle Charge Threshold V = 5V 2.9V +/- 0.1V USB Recharge Threshold V = 5V (Vfloat 130mV) to (Vfloat-60mV) USB USB Current I - 500mA Mode V = 5V, USB Active 500mA Mode 475mA typical, 500mA max USB USB I - 100mA Mode V = 5V, USB Active 100mA Mode 93mA typical, 100mA max USB USB I - Suspend Mode V =5V, USB Suspend 50uA typical , 100uA max USB USB OPERATING PRINCIPLES DC929A-A is the demo board for LTC4089, while is input from either the USB cable or a high voltage DC929A-B is for LTC4089-5. The only difference is that adapter to an intermediate voltage bus VOUT. The inter- the voltage on HVOUT/VOUT of LTC4089 tracks battery mediate voltage bus is preferentially powered from the voltage (0.3V higher than V , with minimum of 3.46V, adapter, then USB and finally if required from the battery BAT maximum 4.6V), while that of LTC4089-5 is fixed at 5V. via an internal ideal diode and an optional external This chip manages the power supplies that would be MOSFET (Q2). The battery charger is a CC/CV timer ter- typical for a USB powered device and/or a high voltage minated type capable of charge currents of up to 1.2A. source, such as fire wire or automotive battery. Power QUICK START PROCEDURE 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC929A-A/B USB POWER SOLUTION IN DFN 6X3 Demonstration circuit DC929A-A/B is easy to set up to Adapter Charging evaluate the performance of the LTC4089/-5. Refer to 6. Ramp up the wall adapter voltage. When the wall Figure 1 for proper measurement equipment setup and adapter exceeds 5.9 volts the LTC4089 will cease follow the procedure below: drawing current from the USB and switch over to the 1. Connect input power supply, meters and output load wall adapter. Both the AC-present LED (D3, red) and as shown in Figure 1, with the following initial values: charge LED (D4, green) are on. PS1 = 0V 7. Note that the V of DC929A-A is about 0.3V above OUT V , indicating the adaptive feature of V to mini- BAT OUT PS2 = 5V mize the charging power loss. The V of DC929A-B OUT PS3 = 2.5V is fixed at 5V. I = 0mA USB 8. Note that the charge current to the battery has in- creased to 700mA. USB Charging 9. Increase the battery voltage to 4.2V and note that the 2. Place the USB ON/OFF jumper (JP3) in the ON posi- charge current falls to 0. This illustrates the constant tion. Place the USB Current jumper (JP2) in the voltage portion of the charging characteristic. In the 500mA position. Turn on the power supplies, the mean time, the charge LED (D4) turns off. charger should activate and the charge LED D4 will il- luminate. The battery will be in trickle charge mode, Battery Powered Operation I is around 70mA. Increase the battery voltage to BAT 10. Set Both USB input voltage and the adapter input above 2.9V the battery charge current (I ) will in- BAT voltage to zero. The battery will now power the load crease to 470mA. Note that the input current from on the System Load Output, illustrating the ideal di- the USB (I ) is about 475mA, which does not exceed USB ode function of the LTC4085. Note that the battery is the USB spec of 500mA. now being discharged. 3. Now increase the load on the SYSTEM LOAD OUTPUT Other (I ). Note that as the output load is increased the OUT charging current is decreased and the USB current Frequency at charge timer cap C4 changes with charging remains within the 500mA limit. current, indicating the adaptive feature to ensure the full charge of battery. 4. Place the USB current jumper in the 100mA position and note that USB input current falls to maintain 11. Pins are provided to all control functions in order to compliance with the USB input current spec. Also simplify wiring of the demo circuit into a system note that as the external load is increased the battery board. will start to discharge into the SYSTEM LOAD 12. NTC function provision has been made for connec- OUTPUT, illustrating the ideal diode function of the tion of an external 10k NTC, for temperature qualified LTC4089 charging. To use this feature set the NTC jumper in 5. Place the USB ON/OFF jumper (JP1) in the OFF posi- the external position and connect the external NTC to tion and note that the USB current falls to under the NTC terminal and ground. 100uA to comply with the USB suspend mode cur- rent. 2