QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801 INVERTING DC/DC CONVERTER LT3483ES6 DESCRIPTION Demonstration circuit 801 is a general purpose posi- value of R2 to 1.21M and for a -5V, change R2 to 511K. Both circuits demonstrate low component tive to negative converter featuring the LT 3483ES6. count and are intended for space-conscious applica- The demo board demonstrates two separate DC/DC tions such as LCD bias, Handheld Computers, Battery converters. One converter generates a -8V at 20mA to Backup, Digital Cameras and OLED Bias. 30mA from a 2.7V-4.2V input using a step up invert- ing charge pump topology. The other uses a dual coupled inductor in an inverting flyback topology to Design files for this circuit board are available. Call generate a -15V at 8mA to 40mA from a 2.7-12V in- the LTC factory. put. This topology is useful to generate output volt- LTC is a registered trademark of Linear Technology Corporation ages of lower, equal or higher magnitude than the input. For example, for a -12V supply just change the Table 1. Performance Summary (T = 25C) A PARAMETERS FOR -8V INVERTER CONDITION VALUE Minimum Input Voltage 2.7V Maximum Input Voltage 4.2V Output Voltage V Vin = 2.5V to 4.2V, Iout = 20mA to 30mA -8V 3% OUT Typical efficiency V =3.3V, Iout =25mA 67% IN Typical Output Ripple V = 3.3V, I = 25mA 60mV IN OUT PP PARAMETERS FOR -15V INVERTER VALUE Minimum Input Voltage 2.7V Maximum Input Voltage 12V Output Voltage V V = 2.7V to 12V, I = 8mA to 40mA -15V 3% OUT IN OUT Typical efficiency V = 6V, I = 20mA 75% IN OUT Typical Output Ripple V V = 6V, I = 20mA 80mV OUT IN OUT PP QUICK START PROCEDURE Demonstration circuit 801 is easy to set up to evalu- on the oscilloscope probe. Measure the input or out- ate the performance of the LT3483ES6. Refer to Fig- put voltage ripple by touching the probe tip directly ure 1 for proper measurement equipment setup and across the Vin or Vout and GND terminals. See Figure follow the procedure below: 2 for proper scope probe technique. NOTE: When measuring the input or output voltage 1. Place jumper in the following positions for testing ripple, care must be taken to avoid a long ground lead of -15V inverter: 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 801 INVERTING DC/DC CONVERTER JP1 On 5. Once the proper output voltages are established, adjust the loads within the operating range and ob- 2. With power off, connect the input power supply to serve the output voltage regulation, ripple voltage, Vin and GND. efficiency and other parameters. 3. Turn on the power at the input. 6. For testing of -8V Inverter repeat steps 1-5 placing 4. Check for the proper output voltages. JP2 in the ON position. NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. Figure 1. Proper Measurement Equipment Setup 2