DC1877A Analog Devices

DEMO MANUAL DC1877A LTC3630AEDHC High Efficiency High Voltage 500mA Synchronous Step-Down Converter Description Demonstration circuit 1877A is a 500mA output DC/DC is available to allow multiple boards to be paralleled for power supply featuring LTC 3630A (DFN package), with increasing output current. 4V to 76V input range. The LTC3630A operates in a high Output voltage between 800mV and V can be programmed IN efficiency Burst Mode operation and includes internal using optional resistors. (Higher voltage output capacitors high and low side switches. The board provides jumper may be required.) selected output voltages of 1.8V, 3.3V, 5V and an option The LTC3630A data sheet gives a complete description of for additional voltages. LTC3630A has internal soft-start the operation and application information. The data sheet and a provision for increasing soft-start time. must be read in conjunction with this demo manual. Included on the board is an ON/OFF jumper that can Design files for this circuit board are available at also be configured as a precision undervoltage lockout. DEMO MANUAL DC1877A Quick s p D This demonstration circuit 1877A can be evaluated using 5. Once the proper output voltages are established, adjust the setup shown in Figure 1. the load and input voltage within the operating range and observe the output voltage regulation, ripple voltage 1. Connect the DVMs to the input and output. Select 5V and other parameters. setting using jumper JP1 (B position) and JP2 (A posi- tion), select ON position for JP3. Notes: 2. With input power supply set for 0V, connect the supply to 1. IMPORTANT: 60V or higher voltage can result in an V and GND terminals using short (less than 10 inches) electric shock if care is not taken. Also, hot plugging IN leads, preferably twisted leads. Connect a suitable load the circuit to a power supply that has more than 40V to V and GND terminals. present at its output can produce a high voltage transient OUT exceeding the absolute maximum input voltage which 3. Slowly increase the input power supply to 10V. Observe can damage the LTC3630A. output voltage and verify that it meets the specifications in Table 1. Measure output voltage with and without the 2. When measuring the input or output voltage ripple, load. care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage 4. Move jumpers JP1 and JP2 to the other two fixed volt- ripple by touching the probe tip directly across the V IN age settings and verify that each output voltage meets or V and GND terminals. See Figure 2 for proper OUT the values as shown in Table 1. scope probe technique. Load Figure 1. Proper Measurement Equipment Setup dc1877af 2 ure roce tart