DEMO MANUAL DC2355A LTC3130EUD 25V, 600mA Buck-Boost DC/DC Converter with 1.6A Quiescent Current Description Demonstration Circuit 2355A features the LTC 3130, a threshold. Jumper JP4 is provided to pull this input up to wide input voltage, wide output voltage operating range, V or tie it directly to GND. See the data sheet for details. IN high efficiency, low noise monolithic DC/DC buck-boost Maximum power point control (MPPC) allows for simple converter. optimization of power transfer between the converter and The LTC3130 operates from input voltages of 2.4V to 25V. a non-ideal supply such as a photovoltaic panel or another The demo board has been designed with the output voltage high impedance source. The DC2355A demo board can set to 5V. The LTC3130 incorporates a proprietary low noise be set to operate in MPPC mode by setting jumper JP3 switching algorithm which optimizes efficiency with input to ON, removing R8 and populating R7 and R9. In most voltages above, below or equal to the output voltage and applications this function can also be realized, often with ensures seamless transitions between operating modes. better efficiency, by using the accurate RUN comparator functionality. See the data sheet for details. The DC2355A demo board has two user selectable operat- ing modes: Burst Mode operation and Fixed Frequency The LTC3130 allows the internal V rail to be fed externally CC PWM (JP2). In PWM Mode, the LTC3130 operates at from the EXTV pin. In some applications the efficiency CC 1.2MHz to allow high efficiency while minimizing the of the converter can be improved by allowing V to be CC solution footprint. back-fed from a supply, such as V . Setting the EXTV OUT CC jumper (JP5) on the demo board to EXT back-feeds V CC The LTC3130 features pin selectable 850mA/450mA aver- through EXTV from V . Setting this jumper to internal CC OUT age inductor current limit. To set the current limit to 850mA (INT) powers V from the V input. See the data sheet CC IN set jumper JP1 to HIGH. For 450mA current limit set for additional details. JP1 to LOW. The lower current limit function is useful when operating from weak, or current limited sources. The LTC3130/LTC3130-1 data sheet has detailed informa- tion about the operation, specifications, and applications A PGOOD open drain output is provided and is pulled of the device. The data sheet should be read in conjunction up to V . This output asserts low when V is below OUT OUT with this quick start guide. regulation. Design files for this circuit board are available at An accurate RUN threshold can be set to enable the con- DEMO MANUAL DC2355A Quick s tart p D Using short twisted pair leads for any power connections 3. Connect a 500mA load (10) to V as shown in OUT and with all loads and power supplies off, refer to Figure 4 Figure 4. for the proper measurement and equipment setup. The 4. Turn on PS1 and slowly increase the voltage until the power supply (PS1) should not be connected to the circuit voltage at V is 5V. IN until told to do so in the procedure below. 5. Verify V is ~5V. 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 < 5V for V to loscope probe. Measure the input or output voltage ripple IN OUT 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 func- loscope probe tip jack. tion of V and the device current limit. Consult the IN data sheet for more information on output current vs 1. Jumper and PS1 settings to start: V . IN PS1: OFF 8. For operation in Burst Mode, move jumper JP2 to JP1: ILIM HIGH BURST MODE. See the data sheet for more informa- JP2: MODE FIXED FREQ tion on Burst Mode operation. JP3: MPPC OFF 9. For operation with the lower current limit move jumper JP1 to LOW. Output current capability is reduced JP4: RUN ON with the lower current limit. See the data sheet for JP5: EXTV EXT more information. CC 2. With power OFF connect the power supply (PS1) as 10. For operation with V powered from V , move jumper CC IN shown in Figure 4. If accurate current measurements JP5 to INT. are desired (for efficiency calculation for example) then NOTE: If V drops out of regulation, check to be sure the OUT connect ammeters in series with supplies as shown. maximum load has not been exceeded, and that V is not IN The ammeters are not required however. below the minimum value for regulation (see data sheet). 95 90 85 V OUT 80 200mV/DIV 75 70 I OUT 65 200mA/DIV EXTV , 600mA LOAD, PWM CC 60 INTV , 600mA LOAD, PWM CC EXTV , 50mA LOAD, BURST CC 55 INTV , 50mA LOAD, BURST CC DC2355A F02 200s/DIV 50 0 5 10 15 20 25 V (V) IN DC2355A F01 Figure 1. DC2355A Typical Efficiency vs Load Figure 2. DC2355A Step Load Response, V = 5V. IN with and without Externally Feeding V Load Step Is from 100mA to 400mA CC dc2355af 2 EFFICIENCY (%) ure roce