DC2049A Analog Devices

DEMO MANUAL DC2049A LT3999EMSE Low Noise Isolated Power Supply DESCRIPTION The DC2049A demonstrates how a power supply regulates The DC2049A produces an isolated 12V and 12V at OUT OUT two output voltage by using the LT 3999 and low dropout up to 200mA each from a 10V ~ 15.5V input voltage range. (LDO) regulators. This board can be modified, by changing the transformer (and duty cycle), to produce other output voltages. The LT3999 is a monolithic push-pull DC/DC driver which features wide input range and small external passive The DC2049A features a small transformer, small inductors components. and capacitors that work at a 1MHz switching frequency. The LT3999 has duty circle control for V compensa- The LT3999 data sheet gives a complete description of the IN tion, which allows for a wide input voltage range and low part, operation and applications information. The data sheet LDO losses. must be read in conjunction with this demo manual. The LT3999EMSE is assembled in a 10-lead plastic MSE pack- The DC2049A employs a push-pull topology that inherently age with a thermally enhanced ground pad. Proper board provides a low-noise solution. The design is well suited layout is essential for maximum thermal performance. See to noise sensitive systems such as medical instruments, the data sheet section Layout Consideration Check List. industrial sensing and control, data conversion and wide band communications. The post regulator LDOs reduce Design files for this circuit board are available at output noise further. For more details about the LDOs, DEMO MANUAL DC2049A QUICK START PROCEDURE DC2049A is easy to set up to evaluate the performance of 3. Turn the input power supply on and make sure the the LT3999EMSE. Refer to Figure 1 for proper measure- voltage is between 10V and 15.5V. ment equipment setup and follow the procedure below: 4. To measure the output noise, connect one end of a BNC 1. Connect Load 1 (positive) between the VOUT1 and GND connector J1. Connect the other end of the BNC cable terminals and another Load 2 (negative) between the to an oscilloscope with a 50 input impedance. Refer VOUT2 and GND terminals. to Application Note 70 for more precise techniques for measuring the output noise. 2. With power off, connect the input power supply to the +VIN and VIN terminals. *J1 is the BNC connector to coaxial cable for noise measurement, please refer to AN70 Appendix B for details. Figure 1. Test Procedure Setup Drawing for DC2049A dc2049af 2