DEMO MANUAL DC2177A-A LT3061 45V V , Micropower, IN Low Noise, 100mA LDO with Output Discharge Description Demonstration circuit 2177A-A features the LT 3061, a polymer capacitor on the input to dampen ringing that micropower, low noise and low dropout voltage linear may occur when the input is hot-plugged using long leads. regulator with output discharge. The input voltage ranges The LT3061 saves energy by being micropower and low from 2.1V to 45V and the maximum output current is dropout. The LT3061 has excellent regulation and fast 100mA. A resistor divider determines the output voltage, response to load transients and also tolerates wide input and a jumper adjusts the divider to set the output voltage voltage variations and discharges its output in a controlled to either 1.2V, 1.5V, 1.8V, 2V, 2.5V, 3.3V, 5V or a voltage manner as required by some image sensor loads. that is user-programmed but requires the installation of The LT3061 targets systems with inputs that are battery- a resistor. The output uses a 10F ceramic capacitor and powered or have multiple sources, especially those with the internal reference is bypassed with a 10nF capacitor sensitive loads. DC2177A-A features the LT3061 in the to reduce output noise and program the soft-start. There 8-lead 2mm 3mm DFN package. The LT3061 data sheet is also a 10nF feedforward capacitor to improve load must be read in conjunction with this demo manual to transient response and decrease noise at higher output properly use or modify demo circuit DC2177A-A. voltages. The position of the VOUTEN jumper either pulls up the SHDN pin to the input supply through a 100k re- Design files for this circuit board are available at sistor, shorts SHDN to ground or floats the SHDN pin so DEMO MANUAL DC2177A-A Quick s p D To use DC2177A-A to evaluate the performance of the 3. Increase the load to the desired output current. Verify LT3061, refer to Figure 1 for the proper measurement that the V voltage is as programmed by the jumper. OUT equipment setup and follow the procedure below: Note: If the output voltage is low, temporarily disconnect 1. With the input supply and load off and turned down, the load to make sure that it is not set too high. make all connections according to Figure 1. Make sure 4. Once the proper output voltage is established, adjust the the jumper to set VOUT is in the proper position for the input voltage and load within the operating range and desired output voltage and the VOUTEN jumper is in observe the output voltage regulation, low quiescent the ON position. current, shutdown, output discharge operation and 2. Turn on the input supplies and increase them to the other parameters. desired input voltages. Note When Setting The Input Voltage: An input voltage that is too close to the programmed output voltage (too low) may cause dropout operation and a loss of output voltage regulation. Also, an input voltage that is too high above the output may increase power dissipation to an unacceptable level. dc2177aaf 2 ure roce tart