QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 516 LOW OUTPUT VOLTAGE, SYNCHRONOUS BOOST CONVERTER LTC3423 and LTC3424 DESCRIPTION Demonstration circuit 516 is a low 1.8V. For 1V minimum battery voltage, output voltage, synchronous boost the LTC3423 can provide up to 350mA, converter featuring LTC3423 (DC516A- and the LTC3424 can provide up to A) or LTC3424 (DC516A-B). 600mA. The LTC3423/LTC3424 is ideal for ap- The switching frequency is set at plications that require an output 1MHz, which gives a good trade-off voltage between 1.5V to 2.6V from a between efficiency and size. See data single alkaline or NiCd/NiMH cell. A sheet for efficiency data at differ- bias voltage of 2.7V to 5.5V is re- ent frequencies. quired to power the internal cir- Design files for this circuit board cuitry. The output voltage is set at are available. Call the LTC factory. Table 1. Performance Summary PARAMETER CONDITION VALUE Maximum Load Current, Min (LTC3423) V = 1V 350mA IN Maximum Load Current, Min (LTC3424) V = 1V 600mA IN Typical Output Ripple V (LTC3423) V = 1V, I = 350mA 18mV OUT IN OUT PP Typical Output Ripple V (LTC3424) V = 1V, I = 600mA 34mV OUT IN OUT PP Nominal Switching Frequency 1MHz Typical Efficiency (LTC3423) V = 1.5V, I = 300mA 90% IN OUT Typical Efficiency (LTC3424) V = 1.5V, I = 600mA 85% IN OUT QUICK START PROCEDURE Demonstration circuit 516 is easy to nals. See Figure 2 for proper scope set up to evaluate the performance of probe technique. the LTC3423 and LTC3424. Refer to NOTE: The board should be connected to Figure 1 for proper measurement the bench power supply with short, equipment setup and follow the proce- thick wires. If long connection wires dure below: are used, electrolytic capacitors are NOTE: When measuring the input or out- recommended between VIN and GND, also put voltage ripple, care must be VDD and GND to damp the voltage over- taken to avoid a long ground lead on shoot during plug-in. Refer to appli- the oscilloscope probe. Measure the cation note 88 for details. input or output voltage ripple by 1. Place jumper JP2 in the FIXED FREQ. touching the probe tip directly position. across the Vin or Vout and GND termi- 1 GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 516 LOW OUTPUT VOLTAGE, SYNCHRONOUS BOOST CONVERTER 2. With power off, connect the input 5. Place jumper JP1 in the RUN posi- power supply to VIN and GND. This tion. voltage is less than 1.8V. 6. Check for the proper output volt- 3. With power off, connect the bias age. Vout = 1.746V to 1.854V. voltage to VDD and GND. This volt- 7. Once the proper output voltage is age is between 2.7V to 5.5V. established, adjust the load within 4. Turn on both power supplies. The the operating range and observe the voltage applied at VDD has to be output voltage regulation, ripple higher than VIN and VOUT. voltage, efficiency and other pa- rameters. + + + + + + LOAD BENCH BENCH SUPPLY SUPPLY Figure 1. Proper Measurement Equipment Setup Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2 + + +