LTC3101EUFE DEMO CIRCUIT 1551A Quick Start Guide LTC3113EDHD 3A Low Noise Buck-Boost DC/DC Converter DESCRIPTION Demonstration Circuit 1551A is a wide Vin range, been designed to operate over the full input voltage highly efficient, fixed frequency buck-boost converter. range, with VOUT set to 3.3V and IOUT of 3.0A. For The unique 4-switch, single inductor architecture pro- VIN < 3V, IOUT capability is reduced. Typical demo vides low noise and seamless operation from input board efficiency is shown below. voltages above, below, or equal to the output voltage. Design files for this circuit board are available. Call The LTC3113 features selectable PWM or Burst Mode the LTC factory. operation and an oscillator with a programmable fre- quency from 300kHz to 2MHz. The LTC3113 can de- liver up to 3A of continuous output current to satisfy most demanding applications. Higher output currents are possible in step-down (buck) mode. L, LTC, LTM, LT, Burst Mode, are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LTC3113 operates with a 1.8V to 5.5V input and output voltage range. The demonstration board has Input Voltage Range: V 1.8V to 5.5V CC VOUT 3.3V IOUT 3.0A for VIN > 3.0V Figure 1. Typical Efficiency 1 LTC3113EDHD QUICK START PROCEDURE Using short twisted pair leads for any power con- 5. Verify VOUT is ~3.3V. nections and with all loads and power supplies off, 6. VIN can now be varied between 1.8V and refer to Figure 2 for the proper measurement and 5.5V. VOUT should remain in regulation. equipment setup. The Battery/Power Supply (PS1) 7. IOUT can also be varied from 0 to 3.0A. For should not be connected to the circuit until told to VIN < 3.0V, maximum IOUT is reduced. do so in the procedure below. This reduction is due to Iin increasing as VIN decreases. Once the input current limit When measuring the input or output voltage ripple, is reached, VOUT will drop out of regulation. care must be taken to avoid a long ground lead on the oscilloscope probe. NOTE: If VOUT drops out of regulation, check to be sure the maximum load has not been exceeded, or that VIN is not below the 1. Jumper, PS1 and LOAD Settings to start: minimum value (1.8V). PS1= OFF 8. For operation in BURST Mode move Jumper JP1 (PWM) = FIXED FREQ JP1 to BURST. IOUT is limited in BURST JP2 = OFF MODE. See the datasheet for more LOAD = 1.0A / 3.32 10W resistor information. 2. With power OFF connect the power supply (PS1) as shown in Figure 2. If accurate current measurements are desired (for NOTE: For applications with large output efficiency calculations for example) then current steps, such as GSM applications, connect an ammeter in series with the additional output capacitance can be added supply as shown. The ammeter is not to the demo board. The capacitor footprints required however. at C4 and C10 are provided for additional output capacitors. 3. Connect the load to VOUT as shown in Figure 2. Again, connect an ammeter if accurate current measurement or monitoring is desired. 4. Turn on PS1 and slowly increase voltage until the voltage at VIN is 3.0V. Move Jumper JP2 to ON. 2