LTC3109EUF DEMO CIRCUIT 1664A QUICK START GUIDE LTC3109EUF Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager DESCRIPTION Demonstration Circuit 1664A featuring the LTC3109 is the average source power integrated over the accumula- a highly integrated DC/DC converter optimized for tion time between bursts. harvesting and managing energy from extremely low The Demonstration Circuit has been set up with a storage input voltage sources such as thermoelectric genera- capacitor that makes it easy to evaluate the general func- tors (TEG). Its unique, proprietary auto-polarity to- tionality of the circuit. The lower value capacitor allows pology allows it to operate from input voltages as low for a fast charge time but limits the pulsed energy that as 30mV, regardless of polarity. can be drawn from it. Space is provided, and alternate The DC 1664A Demonstration Circuit has been optimized part footprints have been built into the PCB to allow ex- for low start-up voltage with a 100:1 turns ratio trans- perimentation with larger capacitors for more energy former. For application where it is desirable to trade-off storage. In a typical application, the larger output capaci- a higher start-up voltage for higher current, a lower turns tors may be used. Refer to the datasheet for more in- ratio transformer can be used. Refer to the LTC3109 formation including equations to properly size the output datasheet for more information. capacitors for a given application. The LTC3109 is designed to accumulate and manage Design files for this circuit board are available. Call energy over a long period of time to enable short bursts the LTC factory. of power to be used to acquire and transmit data. The L, LTC, LTM, LT, Burst Mode, are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. burst must occur at a low enough duty cycle such that the total output energy during the burst does not exceed TABLE 1. Typical Specifications (25C) 50mV-400mV (Typical no load start-up = 30mV) Input Voltage Range VLDO 2.2V VOUT Jumper Selectable from 2.35 to 5.0V VOUT2 Switched Output, VOUT2=VOUT VSTORE 5.25V 1 LTC3109EUF QUICK START PROCEDURE Using short twisted pair leads for any power connections and with all loads and power supplies off, refer to Fig- ure 1 for the proper measurement and equipment setup. The Power Supply (PS1) should not be connected to the circuit until told to do so in the procedure below. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VOUT and GND termin- als. See Figure 2 for proper scope probe technique. 1. Jumper, Power Supply and LOAD Settings to start: PS1= OFF LOADS = OFF JP1(VOUT2) = PULSED JP2= VAUX JP3 = VAUX 2. Turn on PS1 and connect (+) to VINA and (-) to VINB as shown in Figure 1. Slowly increase voltage until the voltage from VINA to VINB is 100mV. Monitor input current. If input current exceeds 60 mA turn off PS1 and look for shorts. 3. Confirm VLDO = 2.2V 4. Confirm LED D3 is lit and blinking. It may take up to 10 seconds for D3 to start blinking. 5. Turn off PS1 and reverse the connection polarity, i.e. connect PS1 (+) to VINB and PS1 (-) to VINA. 6. Move jumper JP1(VOUT2) to OFF. 7. Turn on PS1 and Increase VINA-VINB = -100mV 8. Set LOAD on VLDO to 50A. Set LOAD on VOUT = 25 A. 9. Verify VLDO = 2.2V, Verify VOUT = 5.0V, Verify VSTORE = 5.2V The board is now ready for operation. The voltage on VOUT and VOUT2 can be modified by changing jumpers JP2 and JP3. The jumper combinations are shown on the demo board. Several variations of this design are possible, including increasing the energy storage by populating C11, or C12. Please refer to the datasheet for design equations. 2