QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 883 LI-ION TO 25V STEP-UP DC-DC CONVERTER LT3473EDD DESCRIPTION Demonstration circuit DC883 features the LT®3473 micropower step-up DC/DC converters with integrated Schottky diode and output disconnect circuitry. The output on DC883 is 25V at up to 80mA from a 3~4.2V input, while automatic Burst Mode operation maintains efficiency at light load. The lithium ion battery input voltage range, high output voltage, internal NPN power switch, minimal external components and simple design make the LT3473 an excellent solution for OLED and CCD Bias. The DC883 has a jumper for enabling the output (JP2). Placing the jumper to “OFF”, disables the DC- DC converter and jumper to “ON”, enables the DC-DC converter. There is a jumper (JP1) and a control pin (CTRL) for varying the output voltage. Placing the jumper to “VIN” provides 25V output. Placing the jumper to “CTRL” and changing the voltage at CTRL pin can change the output voltage. The voltage of the PGOOD pin is approximately 0V as the output voltage reaches 90% of final value. Design files for this circuit board are available. Call the LTC factory. LT is a registered trademark of Linear Technology Corporation Table 1. Performance Summary ( TA = 25°C ) PARAMETER CONDITION VALUE Minimum Input Voltage 3V Maximum Input Voltage 4.2V Maximum Output Current Vin = 3 − 4.2V Typical Switching Frequency 80mA 1.2MHz QUICK START PROCEDURE Demonstration circuit 883 is easy to set up to evaluate the performance of the LT3473. Refer to Figure 1. for proper measurement equipment setup and follow the procedure below: 1. Set the input supply between 3V to 4.2V. With power off, connect the input power supply to VIN and GND. Make sure JP2 is set to “ON” and JP1 is set to “VIN”. 5. The output voltage can be controlled by DC voltage at the CTRL terminal. With JP2 placed at “ON” and JP1 placed at “CTRL”, observe the output voltage change with DC voltage applied to the CTRL terminal. The DC voltage range recommended is 200mV ~ 1.5V. The maximum DC voltage is 10V. Refer to the datasheet for further details. 2. Turn on the power at the input. 3. The output voltage should measure about 25V across the “VOUT” terminal to “GND” terminal and the voltage across the PGOOD pin and “GND” terminal should measure about 0V. 4. Test the shutdown function by placing JP2 to “OFF”. Observe the output voltage is about 0.7V lower than the input voltage. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 883 LI-ION TO 25V STEP-UP DC-DC CONVERTER _ + + A _ _ V + V + _ + A_ + + _ Load _ Figure 1. Proper Measurement Equipment Setup Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 883 LI-ION TO 25V STEP-UP DC-DC CONVERTER 3