QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR LTC3410 DESCRIPTION Demonstration circuit 870A-A is a high efficiency, high frequency buck converter, incorporating the LTC3410 monolithic synchronous regulator. The DC870 has an input voltage range of 2.25V to 5.5V, and is capable of delivering up to 300mA of output current. It has an output voltage range from 0.8V to 5V, and an operating frequency of 2.25MHz (allowing the exclusive use of low profile surface mount components). In Burst Mode operation, which is the mode of low load current operation offered by the LTC3410, the DC supply current is typically only 26uA at no load, and less than 1uA in shutdown The DC870 is a very efficient circuit: up to 96%. These features, plus the LTC3410 coming in a tiny, lowprofile 6-pin SC70 package, make the DC870 demo board an ideal circuit for use in battery-powered, hand-held applications. Design files for this circuit board are available. Call the LTC factory. LTC and Burst Mode are trademarks of Linear Technology Corporation Table 1. Performance Summary (TA = 25°C) PARAMETER Minimum Input Voltage CONDITION VALUE 2.25V Maximum Input Voltage Output Voltage VOUT Typical Output Ripple VOUT Output Regulation 5.5V VIN = 2.25V to 5.5V, IOUT = 0A to 0.3A 1.8V ±4% VIN = 5V, IOUT = 0.3A (20 MHz BW) 20mVP–P Line ±1% Load ±1% Nominal Switching Frequency 2.25 MHz QUICK START PROCEDURE The DC870A-A is easy to set up to evaluate the performance of the LTC3410. For proper measurement equipment configuration, set up the circuit according to the diagram in Figure 1. Before proceeding to test, insert shunt on jumper JP1 into the off position, connecting the RUN pin to ground (GND), which shuts down the circuit. NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. 1. Connect the input power supply and the load to the board. Do not hot-plug Vin or increase Vin over the rated maximum supply voltage of 5.5V, or the part may be damaged. Refer to figure 1 for proper measurement equipment setup. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR 2. 3. 4. Apply 3.3V at Vin. Measure Vout; it should read 0V. If desired, one can measure the shutdown supply current at this point. The supply current will be approximately 1uA in shutdown. Turn on the circuit by inserting the shunt in jumper JP1 into the ON position. The output voltage should be regulating. Measure Vout; it should measure 1.8V +/- 2%. Vary the input voltage from 2.25V to 5.5V and adjust the load current from 0 to 0.3A. Vout should read 1.8V +/- 3%. 5. Measure the output ripple voltage at any output current level; it should measure less than 20mVAC. 6. Observe the voltage waveform at the switch node (one pin of the inductor). Verify the switching frequency is between 1.8MHz and 2.7MHz (T = 0.56us and 0.37us), and that the switch node waveform is rectangular in shape. TM The Burst-Mode capability of the LTC3410 can be observed now by reducing load current. When finished, turn off the circuit by inserting the shunt in jumper JP1 into the OFF position. Figure 1. Proper Measurement Equipment Setup 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR Figure 2. Measuring Input or Output Ripple Figure 3. Load Step Response Vin = 3.3V, Vout = 1.8V, Iout Step = 0.2A Trace 1: Output Voltage (50 mV/div AC) Trace 2: Output Current (0.1A/div) 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 870A-A HIGH EFFICIENCY MONOLITHIC SYNCHRONOUS BUCK REGULATOR 4 Bill Of Material Demo Bd. # 870A-A Linear Technology Corporation LTC3410ESC6 1/18/2006 2:59 PM Qty Reference Part Description Manufacture / Part # REQUIRED CIRCUIT COMPONENTS: 1 2 3 4 5 6 7 1 1 1 1 1 1 1 C1 C2 C4 L1 R2 R3 U1 1 2 1 1 C3 R1 CAP., X5R, 2.2uF, 6.3V, 10% 0603 CAP., X5R, 4.7uF, 6.3V, 20% 0603 CAP., C0G, 10pF, 50V, 5% 0402 INDUCTOR, 4.7uH, LQH32CN RES., CHIP, 374K, 1/16W, 1% 0402 RES., CHIP, 301K, 1/16W, 1% 0402 IC.,LTC3410ESC6, SC70 Taiyo Yuden, JMK107BJ225KA Taiyo Yuden, JMK107BJ475MA AVX, 04025A100JAT2A MURATA, LQH32CN4R7M53L AAC, CR05-3743FM Vishay CRCW0402301KFKTD LINEAR TECH., LTC3410ESC6 ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS: CAP., X5R, 0.1uF, 6.3V, 10% 0402 RES., CHIP, 4.7M, 1/16W, 5%, 0402 Page 1 - of - 1 AVX, 04026D104KAT2A AAC, CR05-475JM