SP6126EK1

SP6126, 2A Evaluation Board Manual Easy Evaluation for the SP6126EK1 12V Input, 0 to 2A Output Non-Synchronous Buck Converter Precision 0.60V ±1% High -Accuracy Reference. Small form factor Feature Rich: Single supply operation, Overcurrent protection with auto-restart, on/off function, Preset internal soft start, Type-II internal compensation SP6126EB SCHEMATIC VIN Q1 Si2343DS 2 1 Vin Rs=1k LX C7 0.1uF 6 L1, IHLP-2525CZ 6.8uH, 60mOhm, 4.5A Gate C1 10uF 12V GND VOUT C4 22uF R1 200k, 1% 4 CZ 82pF R2 44.2k, 1% D1 1N4148 R (optional) 10k SP6126 3 VDR Ds MBRA340T3G RZ 2K 3.3V 0-2.0A GND VFB GND 5 SHDN High=Of f * R(10k) is optional. It helps keep the output capacitor discharged under no-load condition. Rev 2/23/07 SP6126 Evaluation Manual Copyright 2007 Sipex Corporation USING THE EVALUATION BOARD 1) Powering Up the SP6126EB Circuit Connect the SP6126 Evaluation Board to an external +12V power supply. Connect with short leads directly to the “VIN” and “GND” posts. Connect a Load between the “VOUT” and “GND” posts, again using short leads to minimize inductance and voltage drop. 2) Measuring Output Load Characteristics It’s best to GND reference scope and digital meters using the Star GND post near the output 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 SP6126 Evaluation Board has been tested and delivered with the output set to 3.30V, by simply changing one resistor, R2, the SP6126 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 FB, which is set to an internal reference voltage of 0.60V. Standard 1% metal film resistors of surface mount size 0603 are recommended. R1  Vout    Vref − 1    Where R1 = 200kΩ. For Vout = 0.60V setting, simply remove R2 from the board. R2 = Note that since the SP6126 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. Using the SHDN (ON/OFF function) Feedback pin serves a dual role of ON/OFF control. The MOSFET driver is disabled when a voltage greater than 1V is applied at FB pin. Maximum voltage rating of this pin is 5.5V. The controlling signal should be applied through a small signal diode as shown on page 1. Under no-load condition an optional 10kOhm bleeding resistor across the output helps keep the output capacitor discharged. POWER SUPPLY DATA The SP6126EB is designed with an accurate 2% reference over line, load and temperature. Figure 1 data shows a typical SP6126 Evaluation Board efficiency plot, with efficiencies to 92% and output currents to 2.5A. SP6126 Load Regulation in Figure 2 shows no change in output voltage from no load to 2A load. Figures 3 and 4 show the transient response of the SP6126. Figures 5 and 6 show a controlled start-up with no load and 2A load when power is applied where the input current rises smoothly as the soft-start ramp increases. Figures 7 and 8 show the output ripple under no load and 2A load. 2 Typical Performance Characteristics SP6126 Efficiency versus Iout, Vin=12V,Ta=25C 100 3.320 SP6126 Load Regulation Vin=12V 90 Efficiency (%) 3.315 Vout (V) Vout=3.3V Vout=5V Vout=2.5V 80 3.310 70 3.305 60 0.0 0.5 1.0 Iout (A) 1.5 2.0 2.5 3.300 0.0 0.5 1.0 Iout (A) 1.5 2.0 Figure 1- Step load 1-2A, ch1: Vin ch2: Vout, ch3: Iout Figure 2- Step load 0.3-2A, ch1: Vin ch2: Vout, ch3: Iout Figure 3- Step load 1-2A, ch1: Vin ch2: Vout, ch3: Iout Figure 4- Step load 0.3-2A, ch1: Vin ch2: Vout, ch3: Iout Figure 5- Startup no load, ch1: Vin ch2: Vout, ch3: Iout Figure 6- Start up 2A, ch1: Vin ch2: Vout, ch3: Iout 3 Typical Performance Characteristics Figure 7- Output ripple at 0A is 11mV, ch1: Vin, ch2: Vout, ch3: Iout Figure 8- Output ripple at 2A is 18mV, ch1: Vin, ch2: Vout, ch3: Iout 4 LOOP COMPENSATION The SP6126 includes Type-II internal compensation components for loop compensation. External compensation components are not required for systems with tantalum or aluminum electrolytic output capacitors with sufficiently high ESR. Use the condition below as a guideline to determine whether or not the internal compensation is sufficient for your design. Type-II internal compensation is sufficient if the following condition is met: f ESRZERO < f DBPOLE where: f ESRZERO = 1 2.π .R ESR .C OUT ………………. (1) ……….. (2) f DBPOLE = 1 2.π . L ⋅ C OUT ………… (3) Creating a Type-III compensation Network The above condition requires the ESR zero to be at a lower frequency than the doublepole from the LC filter. If this condition is not met, Type-III compensation should be used and can be accomplished by placing a series RC combination in parallel with R1 as shown below. The value of CZ can be calculated as follows and RZ selected from table 1. CZ = L⋅C ………….. (4) R1 fESRZERO/fDBPOLE 1X 2X 3X 5X >= 10X RZ 50K 40K 30K 10K 2K Table1- Selection of RZ 5 SP6126 Vout CP1 2pF RZ CZ CZ2 130pF RZ2 200k VFB R1 200k, 1% Error Amplif ier Figure 9- RZ and CZ in conjunction with internal compensation components form a Type-III compensation Loop Compensation for the SP6126EB L = 6.8uH, C = 22uF/5mOhm ceramic capacitor From equation (2) fESRZERO = 1.45MHz. From equation (3) fDBPOLE = 13 kHz. Since the condition specified in (1) is not met, Type-III compensation has to be used by adding external components RZ and CZ. Using equation (4) CZ is calculated 61.2pF. After bench tests a 82uf was selected for optimum performance. Following the guideline given in table 1, a 2kOhm RZ was used. + Vref =0.6V R2 6 PCB LAYOUT DRAWINGS Figure 10. SP6126EB Component Placement Figure 11. SP6126EB PCB Layout Top Side Figure 12. SP6126EB PCB Layout Bottom Side 7 Line No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ref. Des. PCB U1 Q1 DS L1 D1 C1 C6 C7 CZ R1 R2 RZ R VIN, VOUT, GND, GND, SHDN Qty. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 Manuf. Sipex Sipex Vishay Semi On Semi Vishay MCC MURATA MURATA MURATA MURATA VISHAY/DALE VISHAY/DALE VISHAY/DALE ROHM Vector Electronic Manuf. Layout Part Number Size 146-6613-00 1.175"x1.934" SP6126EK1 TSOT-6 Si2343DS SOT-23 MBRA340T3 SMA IHLP2525CZ 6.86x6.47mm 1N4148WX SOD323 GRM21BR61C106K 0805 GRM21BR60J226M 0805 GRM18ER61E104K 0603 GRM18ER61H820K 0603 CRCW0603200K 0603 CRCW060344K2 0603 CRCW06037K15 0603 MCR18EZPF1002 1206 K24C/M .042 Dia Component SP6126EB Non-synchronous Buck Controller PFET, 30V, 86mOhm Schotkky, 40V, 3A 6.8uH Coil 8A 60mOhm Fast Switching Diode 500mW 10 uF Ceramic X5R 16V 22uF Ceramic X5R 6.3V 0.1uF Ceramic X5R 82pF Ceramic C0G 50V 200k 44.2K 2.00K 10.0K Test Point Post Vendor Phone Number 408-934-7500 408-934-7500 402-563-6866 602-244-6600 914-347-2474 818-701-4933 770-436-1300 770-436-1300 770-436-1300 770-436-1300 402-563-6866 402-563-6866 402-563-6866 800-344-4539 800-344-4539 Table 2- SP6126EB List of Materials INDUCTORS - SURFACE MOUNT Inductor Specification Size Inductor Type DCR Isat mOhms (A) LxW(mm) Ht.(mm) 60.0 8.00 6.47x6.86 3.00 Shielded Inductance (uH) 6.8 Manufacturer/Part No. VISHAY Manufacturer Website www.vishay.com Capacitance( uF) 10 22 Manufacturer/Part No. AVX 1206YD106MAT2A AVX 08056D226MAT2A CAPACITORS - SURFACE MOUNT Capacitor Specification Size ESR Ripple Current Voltage Capacitor Manufacturer ohms (max) (A) @5C Delta LxW(mm) Ht.(mm) (V) Type Website 0.005 3.00 3.20x1.60 1.60 16.0 X5R Ceramic www.avx.com 0.005 2.60 2.00x1.25 1.25 6.3 X5R Ceramic www.avx.com MOSFETS - SURFACE MOUNT MOSFET P-Ch Manufacturer/Part No. VISHAY Si2343DS RDS(on) ohms (max) 86.00 MOSFET Specification Qg ID Current Voltage (A) nC (Typ) nC (Max) (V) 3.1 14.0 21.0 30.0 Foot Print SOT-23 Manufacturer Website www.vishay.com Table 3- SP6126EB Suggested Components and Vendor Lists ORDERING INFORMATION Model Temperature Range Package Type SP6126EB ..….........................− 40°C to +85°C...................SP6126 Evaluation Board SP6126EK1............................ − 40°C to +85°C.......................................6-pin TSOT-6 8