QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200 2A 100KHZ HIGH VOLTAGE BUCK CONVERTER LT3430-1 DESCRIPTION Demonstration circuit 1200 is a 60V, 100kHz, 2A load current, monolithic step-down DC/DC switching converter using the LT3430-1. With its wide input voltage range, 3A internal power switch, and thermally enhanced package, the LT3430-1 is a very versatile and powerful IC for DC/DC converters that require compact space and a wide variety of input voltage ranges. The constant 100kHz switching frequency allows the input voltage to be as high as 60V for a 3.3V output without pulse-skipping. The current-mode control topology creates fast transient response and good loop stability with a minimum number of external compensation components and the use of ceramic input and output capacitors if desired. The low resistance internal power switch (0.1Ω) and 100kHz switching frequency give efficiencies up to 90%. The 30µA shutdown current extends battery life. The wide input range allows step-down configurations with input voltages between 5.5V and 60V. The LT3430-1 is synchronizable above 125kHz. Please refer to the datasheet for details. Demonstration Circuit 1200 is a step-down converter using the LT3430-1. The circuit is designed for 5.560V input to 3.3V output at 2A load current for automotive, industrial, portable computers, battery chargers, and distributed power systems. This board was designed for wide input voltage range applications with low component count and up to 2A of load current. The low-ESR tantalum output capacitor reduces output voltage ripple. The LT3430/LT3430-1 datasheet is available at www.linear.com for more details regarding LT3430-1 applications and specifications. Design files for this circuit board are available. Call the LTC factory. LT is a trademark of Linear Technology Corporation Table 1. Typical Performance Summary PARAMETER CONDITION VALUE Steady State Input Voltage Range VOUT = 3.3V, IOUT <= 2A 5.5 – 60V Maximum Transient Input Voltage All Vout (customized) 60V VOUT IOUT <= 2A 3.3V ±3% Maximum Output Current 2A Typical Switching Frequency 100kHz Efficiency VIN = 12V, VOUT = 3.3V, IOUT = 500mA 85% Output Voltage Ripple VIN = 12V, VOUT = 3.3V, IOUT = 2A 25mVPK-PK 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200 2A 100KHZ HIGH VOLTAGE BUCK CONVERTER QUICK START PROCEDURE Demonstration circuit 1200 is easy to set up to evaluate the performance of the LT3430-1. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: NOTE: Make sure that the input voltage does not exceed 60V. NOTE: Do not hotplug the input at voltages above 24V to prevent input overvoltage. load to the Vout and GND terminals on the board. 4. Connect an ammeter in series with output load to measure output current. 5. Connect a voltmeter across the Vin and GND ter- minals to measure input voltage. 6. Connect a voltmeter across the Vout and GND ter- minal to measure output voltage. 1. Connect the 5.5-60V input power supply to the Vin and GND terminals on the board with the power supply turned OFF. 2. Connect an ammeter in series with the input supply to measure input current. 3. Connect either power resistors or an electronic 7. After all connections are made, turn on input power and verify that the output voltage is 3.3V. 8. The synchronization and shutdown functions are optional and their pins can be left floating (disconnected) if their functions are not being used. Figure 1. Proper Measurement Equipment Setup 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200 2A 100KHZ HIGH VOLTAGE BUCK CONVERTER 100% 95% 90% 5 V IN 85% 12 V IN 80% 2 4 V IN 75% 4 8 V IN 70% 65% 60% 55% 50% 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Figure 4. Typical VOUT ripple 12VIN 2A load LOA D CURRENT (A ) Figure 2. Typical shutdown current versus input voltage µ 40 35 30 25 20 15 Figure 5. Typical VOUT ripple 48VIN 2A load 10 5 0 0 10 20 30 40 50 60 INP UT VOLTA GE (V) Figure 3. Typical shutdown current versus input voltage 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200 2A 100KHZ HIGH VOLTAGE BUCK CONVERTER 4