SP6132 Evaluation Board Manual Easy Evaluation for the SP6132 12V Input, 0 to 10A Output Synchronous Buck Converter Precision 0.80V with 1% High Accuracy Reference. UVIN and Output Dead Short Circuit Shutdown Protection Features. High Efficiency: 94% Feature Rich: UVIN, Programmable Softstart, External VCC Supply and Output Dead Short Circuit Shutdown Protection. SP6132EB SCHEMATIC Rev 09/15/03 SP6132 Evaluation Manual Copyright 2003 Sipex Corporation USING THE EVALUATION BOARD 1) Powering Up the SP6132 Circuit Connect the SP6132 Evaluation Board with an external +12V power supply. Connect with short leads and large diameter wire directly to the VIN and GND posts. Connect a Load between the VOUT and GND posts, again using short leads with large diameter wire to minimize inductance and voltage drops. 2) Measuring Output Load Characteristics Its best to GND reference scope and digital meters using the Star GND post in the center of the board. VOUT ripple can best be seen touching probe tip to the pad for COUT and scope GND collar touching Star GND post avoid a GND lead on the scope which will increase noise pickup. 3) Using the Evaluation Board with Different Output Voltages While the SP6132 Evaluation Board has been tested and delivered with the output set to 3.30V, by simply changing one resistor, R2, the SP6132 can be set to other output voltages. The relationship in the following formula is based on a voltage divider from the output to the feedback pin VFB, which is set to an internal reference voltage of 0.80V. Standard 1% metal film resistors of surface mount size 0603 are recommended. Vout = 0.80V ( R1 / R2 + 1 ) or R2 = R1 / ( Vout / 0.80V ) 1 Where R1 = 68.1K and for Vout = 0.80V setting, simply remove R2 from the board. Furthermore, one could select the value of R1 and R2 combination to meet the exact output voltage setting by restricting R1 resistance range such that 50K R1 100K for overall system loop stability. Note that since the SP6132CU Evaluation Board design was optimized for 12V down conversion to 3.30V, changes of output voltage and/or input voltage will alter performance from the data given in the Power Supply Data section. In addition, the SP6132CU provides short circuit protection by sensing Vout at GND however for a better and robust current limit a comparator circuit could be used as shown on the SP6132EB Schematic. POWER SUPPLY DATA The SP6132 is designed with a very accurate 1.0% reference over line, load and temperature. Figure 1 data shows a typical SP6132CU Evaluation Board Efficiency plot, with efficiencies to 94% and output currents to 10A. SP6132CU Load Regulation shown in Figure 2 shows only 0.3% change in output voltage from no load to 10A load. Figures 3 and 4 illustrate a 0A to 5.0A and 5.0A to 10A Load Step. Start-up Response in Figures 5, 6 and 7 show a controlled start-up with different output load behavior when power is applied where the input current rises smoothly as the Softstart ramp increases. In Figure 8 the SP6132CU is configured for hiccup mode in response to an output dead short circuit condition and will Softstart until the over-load is removed. Figure 9 and 10 show output voltage ripple less than 60mV at no load to 10A load. While data on individual power supply boards may vary, the capability of the SP6132 of achieving high accuracy over a range of load conditions shown here is quite impressive and desirable for accurate power supply design. 2