DC1144A-B Analog Devices

DEMO MANUAL DC1144A LT3580EDD Boost/ Inverting Regulator DESCRIPTION Demonstration circuits 1144A-A and 1144A-B feature the linear regulator built into the board that will allow the IC LT 3580EDD in Boost/Inverting Regulator configurations. to be powered from a lower voltage. If this option is used, The demo circuits demonstrate small size and low com- just cut the trace as shown in Figure 6 and install the op- ponent count. The boost is designed to convert a 3V to tional emitter follower regulator on the back of the board. 10V source to 12V at 300mA while the inverter converts The DC1144A-B can easily be configured into a SEPIC a 5V to 12V source to 12V at 350mA. Both converters converter, just switch the positions of L2 and D2 as shown use only one feedback resistor to set the output voltage. in Figure 6. The LT3580 operates with inputs as high as 32V but in The LT3580 includes many other features such as Synchro- these demo boards the input is limited by the voltage nization to external clock, User Configurable Undervoltage rating of the input capacitors and the magnitude of the Lockout, Soft-start, Frequency Foldback, and it is easily boost output. In a boost converter the input needs to be configured as boost or inverting converter. less than the output. These circuits are intended for space-conscious applica- Care must be taken when operating the LT3580 at high tions such as Local Bias Supplies, TFT-LCD Bias Supplies, input voltages as the junction temperature increases due GPS Receivers, VFD Bias Supplies and DSL Modems. to higher internal dissipation. Higher switching frequencies Design files for this circuit board are available at also increase the internal dissipation. DEMO MANUAL DC1144A QUICK START PROCEDURE Demonstration circuit 1144A is easy to set up to evaluate the 1. Place jumpers in the following positions: performance of the LT3580EDD. Refer to Error Reference JP1 ON source not found. and Figure 2 for proper measurement 2. With power off, connect the input power supply to V equipment setup and follow the procedure below: IN and GND. NOTE: When measuring the input or output voltage ripple, 3. Turn on the power at the input. care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage 4. Check for the proper output voltages. ripple by touching the probe tip directly across the VIN or NOTE: If there is no output, temporarily disconnect the VOUT and GND terminals. See Error Reference source load to make sure that the load is not set too high. not found. for proper scope probe technique. 5. Once the proper output voltage is established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Figure1. Proper Measurement Equipment for DC1144A-A dc1144af 2