DEMO CIRCUIT 879 LTC3525-3.3 AND LTC3525-5 QUICK START GUIDE DESCRIPTION LTC3525-3.3 and LTC3525-5 Micropower Synchronous Step-Up Converter with Output Disconnect Demonstration circuit 879 is a Micropower Synchronous Step-Up Converter with Output Disconnect featuring the LTC3525-3.3 and LTC3525-5. The LTC3525 is a high performance Burst Mode operation only, synchronous boost converter. The LTC3525 incorporates a feature that maximizes efficiency by adjusting the peak and valley of the inductor current as a function of load. The demo board has two assembly versions: DC879A-A and DC879A-B. The DC879A-A offers fixed 3.3V output. The DC879A-B offers fixed 5V output. They offer a compact, high efficiency solution in single cell or dual cell alkaline or Li-ion applications. Only three small external components are required. The LTC3525 datasheet gives a complete description of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for demo circuit 879. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT and PowerPath are trademarks of Linear Technology Corporation. PERFORMANCE SUMMARY Specification s are at TA = 25°C SYMBOL VIN VIN VOUT PARAMETER Input Supply Range Input Supply Range Output Voltage Range VOUT VOUT Output Voltage Range Output Voltage Range VOUT IQ IQ η η Output Voltage Range Quiescent Current at No Load Quiescent Current at No Load Efficiency Efficiency CONDITIONS DC879A-A DC879A-B 1.8V < VIN < 3.2V, ILOAD < 140mA (DC879A-A) 1V < VIN < 3.2V, ILOAD < 60mA (DC879A-A) 3V < VIN < 4.5V, ILOAD < 175mA (DC879AB) 1V < VIN < 4.5V, ILOAD < 40mA (DC879A-B) VIN = 2.4V (DC879A-A) VIN = 3V (DC879A-B) VIN = 2.4V, ILOAD = 100mA VIN = 3V, ILOAD = 175mA MIN 1 1 3.168 TYP 3.3 MAX 3.2 4.5 3.432 UNITS V V V 3.168 4.8 3.3 5 3.432 5.2 V V 4.8 5 16 21 83 86 5.2 V µA µA % % QUICK START PROCEDURE Demonstration circuit 879 is easy to set up to evaluate the performance of the LTC3525-3.3 and LTC3525-5. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: NOTE. 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 VIN or VOUT and GND terminals. See Figure 2 for proper scope probe technique. 1. Verify the jumper in the following position: JP1 ON 1 LTC3525-3.3 AND LTC3525-5 2. With power off, connect the input power supply to Vin and GND. NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 5. Once the proper output voltages are established, ad- 3. Turn on the power at the input. NOTE. Make sure that the input voltage does not exceed 6V. 4. Check for the proper output voltages. VOUT = 3.3V for just the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. DC879A-A and VOUT = 5V for DC879A-B. Figure 1. Proper Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 2 LTC3525-3.3 AND LTC3525-5 3