SP6134 (2A MAX.) Evaluation Board Manual Easy Evaluation for the SP6134CU 12V Input, 0 to 2A Output Synchronous Buck Converter Precision 0.80V with 1% High Accuracy Reference. UVIN and Output Dead Short Circuit Shutdown Protection Features. High Efficiency: 92% Feature Rich: UVIN, Programmable Softstart, External VCC Supply and Output Dead Short Circuit Shutdown Protection. SP6134EB SCHEMATIC Rev 12/27/04 SP6134 Evaluation Manual Copyright 2004 Sipex Corporation USING THE EVALUATION BOARD 1) Powering Up the SP6134EB Circuit Connect the SP6134 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 GND2 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 SP6134 Evaluation Board has been tested and delivered with the output set to 3.30V, by simply changing one resistor, R2, the SP6134 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) => 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 SP6134 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. POWER SUPPLY DATA The SP6134EB is designed with a very accurate 1.0% reference over line, load and temperature. Figure 1 data shows a typical SP6134CU Evaluation Board efficiency plot, with efficiencies to 91% and output currents to 2A. SP6134CU Load Regulation shown in Figure 2 shows only 0.02% change in output voltage from no load to 2A load. Figures 3 and 4 illustrate a 1A to 2A and 0A to 2A Load Steps. 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 SP6134CU 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 22mV at no load to 2A load. While data on individual power supply boards may vary, the capability of the SP6134CU of achieving high accuracy over a range of load conditions shown here is quite impressive and desirable for accurate power supply design. 2