QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1158A MONOLITHIC SYNCHRONOUS BUCK REGULATOR LTC3564 DESCRIPTION Demonstration circuit DC1158A is a high efficiency makes the LTC3564 ideally suited for single Li-Ion monolithic synchronous buck regulator using a battery-powered or 3.3V to 5V input voltage appli- constant frequency, current mode architecture fea- cations. 100% duty cycle provides low dropout turing LTC3564. Its high switching frequency of operation, extending battery life in portable sys- 2.25MHz allows the use of small surface mount tems. Automatic Burst Mode operation increases inductors and capacitors. Supply current during efficiency at light loads, further extending battery operation is only 20uA dropping to below 1uA in runtime. Gerber files for this circuit are avail- shutdown. The 2.5V to 5.5V input voltage range able. Call the LTC Factory. Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE Input Voltage 2.5V to 5.5V Output Voltage V I =0A to 1.25A V 0.5% OUT OUT OUT Maximum Output Current 1.25A DC Supply Current V = 0.5V or V = 90%, I = 0A 300A FB OUT OUT Nominal Switching Frequency V = 0.6V or V = 100% 2.25MHz FB OUT QUICK START PROCEDURE The DC1158A is easy to set up to evaluate the the V and GND terminals. Refer to Figure 2 OUT performance of the LTC3564. For a proper for the proper measurement equipment setup. measurement equipment configuration, set up 2. Before proceeding to operation, insert the circuit according to the diagram in Figure 2. jumper shunt XJP1 into the OFF position and NOTE: When measuring the input or output volt- insert jumper shunt into XJP2, XJP3 or XJP4 age ripple, care must be taken to avoid a long for voltages of 1.2V, 1.5V or 1.8V respectively. ground lead on the oscilloscope probe. Measure Set the load output current to less than 1.25A. the input or output voltage ripple by touching the An optional output voltage can be set by popu- probe tip directly across the V or V and GND lating resistor RFB6, removing RFB5 and mov- IN OUT terminals. See the Measurement Equipment Set- ing the shunt jumper to JP5. up diagram in Figure 1 for proper scope probe 3. Apply 5V at V . Measure V it should IN OUT technique. read 0V. If desired, one can measure the shut- Please follow the procedure outlined below for down supply current at this point. The supply cur- proper operation. rent will be about 1 A in shutdown. 1. Connect the input power supply to the V 4. Turn on V by changing shunt XJP1 from IN OUT and GND terminals. Connect the load between the OFF position to the ON position. The out- put voltage should measure according to the 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1158A MONOLITHIC SYNCHRONOUS BUCK REGULATOR voltage set by the shunt jumper in XJP2, XJP3 6. Vary the V load current from 0 to 1.25A, OUT or XJP4. and the output voltage should be within a toler- ance of +/- 0.5%. 5. Vary the input voltage between 2.5V and 5.5V and the output voltage should be within +/- 0.4% tolerance. Warning - If the power for the demo board is car- small tantalum capacitor (for instance, AVX part ried in long leads, the input voltage at the part TAJW686M010) on the pads between the in- could ring, which could affect the operation of put power and return terminals on the bottom of the circuit or even exceed the maximum voltage the demo board. The (greater) ESR of the tanta- rating of the IC. To eliminate the ringing, insert a lum will dampen the (possible) ringing voltage due to the use of long input leads. On a normal, typical PCB, with short traces, the capacitor is not needed. Figure 1. Measuring Input or Output Ripple + A A V + V + + VIN + VOUT LOAD + Figure 2. Equipment setup to test LTC3564 2