DEMO MANUAL DC2397A LTC3130EUD-1 25V, 600mA Buck-Boost DC/DC Converter with 1.6A Quiescent Current DESCRIPTION Demonstration circuit 2397A features the LTC 3130-1, a Maximum power point control (MPPC) allows for simple wide input voltage, wide output voltage operating range, optimization of power transfer between the converter high efficiency, low noise monolithic DC/DC buck-boost and a non-ideal supply such as a photovoltaic panel or converter. another high impedance source. The DC2397A demo board can be set to operate in MPPC mode by setting jumper The LTC3130-1 has 4-pin selectable output voltages JP4 to ON, removing R4 and populating R5 and R6. In and operates from input voltages of 2.4V to 25V. The most applications this function can be realized, often with LTC3130-1 incorporates a proprietary low noise switching better efficiency, by using the accurate RUN comparator algorithm which optimizes efficiency with input voltages functionality. See the data sheet for details. above, below, or equal to the output voltage and ensures seamless transitions between operating modes. A PGOOD open-drain output is provided and is pulled up to V . This output asserts low when V is below OUT OUT The LTC3130-1s user selectable output voltages are 1.8V, regulation. 3.3V, 5.0V and 12V. To set the desired output voltage on the DC2397A, use the V JUMPER CONFIGURATION The LTC3130-1 allows the internal V rail to be fed OUT CC table on the front of the board to determine the jumper externally from the EXTV pin. In some applications the CC settings for JP2 and JP3. efficiency of the converter can be improved by allowing V to be back-fed from a supply, such as V . Setting CC OUT The DC2397A demo board has two user selectable oper- the EXTV jumper (JP6) on the demo board to EXT CC ating modes: Burst Mode operation and fixed frequency back-feeds V through EXTV from V . Setting this CC CC OUT PWM (JP1). In PWM Mode, the LTC3130-1 operates at jumper to internal (INT) powers V off the V input. CC IN 1.2MHz to allow high efficiency while minimizing the See the data sheet for additional details. solution footprint. The LTC3130/LTC3130-1 data sheet has detailed informa- Internal compensation reduces footprint size by reducing tion about the operation, specifications, and applications of the number of external components. This also simplifies the device. The data sheet should be read in conjunction the design process and reduces external component cost. with this quick start guide. An accurate RUN threshold can be set to enable the Design files for this circuit board are available at converter at a desired input voltage. The DC2397A demo DEMO MANUAL DC2397A QUICK START PROCEDURE Using short twisted pair leads for any power connections 3. Connect a 50mA load (240) to V as shown in OUT and with all loads and power supplies off, refer to Figure4 Figure 4. for the proper measurement and equipment setup. The 4. Turn on PS1 and slowly increase the voltage until power supply (PS1) should not be connected to the circuit the voltage at V is 3V. IN until told to do so in the procedure below. 5. Verify V is ~12V. OUT When measuring the input or output voltage ripple, care 6. V can now be varied between 2.4V and 25V. The must be taken to avoid a long ground lead on the oscil- IN load may need to be reduced for V < 3V for V loscope probe. Measure the input or output voltage ripple IN OUT to remain in regulation. by touching the probe tip directly across the V or V IN OUT and GND terminals (see Figure 5), or by using an oscil- 7. The load can be varied. The maximum load is a loscope probe tip jack. function of V and the device current limit. Consult IN the data sheet for more information on output cur- 1. Jumper and PS1 settings to start: rentvsV . IN PS1: OFF 8. V can be varied by setting jumpers JP2 and JP3 OUT JP1: MODE FIXED FREQ in accordance with the V JUMPER CONFIGU- OUT JP2: VS1 V CC RATION table on the front of the DC2397A demo JP3: VS2 V board. CC JP4: MPPC OFF 9. For operation in Burst Mode, move jumper JP1 to JP5: RUN ON Burst Mode position. See the data sheet for more information on Burst Mode operation. JP6: EXTV INT CC 10. For operation with V powered from V , move 2. With power OFF connect the power supply (PS1) as CC OUT JP6 to EXT. shown in Figure 4. If accurate current measurements are desired (for efficiency calculation for example) NOTE: If V drops out of regulation, check to be OUT then connect ammeters in series with supplies as sure the maximum load has not been exceeded, and shown. The ammeters are not required however. that V is not below the minimum value for regula- IN tion (see data sheet). 100 90 80 70 V : 500mV/DIV OUT 60 50 40 30 I : 200mA/DIV OUT 20 10 0 1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 LOAD CURRENT (A) DC2397A F01 V = 5V, PWM MODE IN 200s/DIV V = 5V, Burst Mode OPERATION IN V = 24V, Burst Mode OPERATION IN V = 24V, PWM MODE IN Figure2. DC2397A Step Load Response. V = 12V, IN V = 12V, Load Step is from 100mA to 400mA. Figure 1: DC2397A Typical Efficiency vs Load. V = 12V. OUT OUT dc2397af 2 EFFICIENCY (%)