QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 760 BOOST AND INVERTING DC/DC CONVERTERS LT3472EDD DESCRIPTION Demonstration circuit 760 is a Dual, 1.1MHz output voltage. Both circuits are designed to demon- Boost/Inverter in 3mmx 3mm DFN featuring the strate the capacitor programmable Soft-Start feature, LT3472EDD. The demo circuit demonstrates small advantages of the 1.1MHz constant switching fre- size and low component count in a Boost Circuit and quency and the internal 36V switches. Both outputs an Inverting Circuit. The Boost Converter is designed on this demo circuit can be modified for higher volt- to convert a 2.7V-4.2V input to 15V output at 25mA- ages. These circuits are intended for space-conscious 45mA load. The Inverting Circuit generates a -8V out- applications such as CCD Bias, TFT LCD Bias, OLED put at 35mA-65mA from the same input. Since the Bias and +/- Rail Generation for Op Amps. maximum Vin of the LT3472DD is 16V, this demo cir- Design files for this circuit board are available. Call cuit will work well at higher inputs. The only limitation the LTC factory. is the 10V rating of the input capacitor. The LT3472 LT is a trademark of Linear Technology Corporation features integrated Schottky diodes for both outputs and requires only one resistor (per output) to set the Table 1. Performance Summary (T = 25C) A PARAMETERS FOR 15V BOOST CIRCUIT CONDITION VALUE Minimum Input Voltage 2.7v Maximum Input Voltage 4.2V Output Voltage V V = 2.7V, I = 0mA to 25mA 15V 5% OUT IN OUT Output Voltage V V = 4.2V, I = 0mA to 45mA 15V 5% OUT IN OUT Maximum Output Current Vin = 2.7V 25mA Maximum Output Current Vin = 4.2V 45mA Typical Output Ripple V V = 3.3V , I = 35mA 20mV OUT IN OUT PP Typical efficiency V = 4.2V, Vout = 15V 30mA and -8V turned off 82% IN PARAMETERS FOR -8V INVERTING CIRCUIT VALUE Output Voltage V V = 2.7V, I = 0mA to 35mA -8V 5% OUT IN OUT Output Voltage V V = 4.2V, I = 0mA to 65mA -8V 5% OUT IN OUT Maximum Output Current Vin = 2.7V 35mA Maximum Output Current Vin = 4.2V 65mA Typical Output Ripple V V = 3.3V, I = 50mA 10mV OUT IN OUT PP Typical efficiency V = 4.2V, Vout = 15V 0mA and -8V 30mA 71% IN 1 GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 760 BOOST AND INVERTING DC/DC CONVERTERS QUICK START PROCEDURE Demonstration circuit 760A is easy to set up to evalu- 2. With power off, connect the input power supply to ate the performance of the LT3472EDD. Refer to Vin and GND. Figure 1 for proper measurement equipment setup 3. Turn on the power at the input. and follow the procedure below: 4. Check for the proper output voltages. NOTE: When measuring the input or output voltage NOTE: If there is no output, temporarily disconnect ripple, care must be taken to avoid a long ground lead the load to make sure that the load is not set too on the oscilloscope probe. Measure the input or out- high. put voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 5. Once the proper output voltages are established, 2 for proper scope probe technique. adjust the loads within the operating range and ob- serve the output voltage regulation, ripple voltage, 1. Place jumpers in the following positions: efficiency and other parameters. JP1 On Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2