SP6136

SP6136 (7A MAX.) Evaluation Board Manual Easy Evaluation for the SP6136ER1 12V Input, 0 to 7A Output Synchronous Buck Converter Precision 0.80V ±1% High Accuracy Reference Small form factor Feature Rich: Single supply operation, Overcurrent protection with auto-restart, Power Good Output, Enable input, Fast transient response, Short Circuit Shutdown Protection, Programmable soft start TSSOP Package & SMT components for small, low profile Power Supply SP6136EB SCHEMATIC 1 VCC 1 1 VCC C1 0.1uF DBST SD101AWS 8765 MT 16 15 14 13 CVCC 4.7uF UVIN VC C VIN BST 10V 1 2 3 AGND 1 2 R3 NP 1 10.0k,1% UVIN 1 3 R4 NP 12pF CZ2 CF1 22pF 560pF RZ2 30.9K,1% CZ3 270pF RZ3 1K 1% R2 21.5k,1% VFB R1 68.1k,1% C2 0.01uF 1 R5 5 6 7 8 SS CSS 47nF J1 PTC36SAAN CP1 GL 4 123 7 SS 5 ISN 5.11k,1% RS1 ISP 5.11k,1% RS2 Co 100uF 6.3V 1210 17 4 GL 12 11 10 9 CS 0.1uF RS3 10K1% CSP 8765 6.8nF MB Si4886DY 13.5mOhm Inter-Technical SC7232-2R2 2.2uH, 10.4 mOhm 1 VOUT CBST 0.1uF GH SWN ISP ISN SS GH SWN 4 123 Si4354DY 18.5mOhm Ci 22uF 16V 1210 6 VIN 12V 1 8 GND CIN & COUT CERAMIC 1210 X5R PGND GND SP6136 PW RGD COM P EN U1 Note: All resistors & capacitors size 0603 unless other wise specified DIEPAD VFB EN 1 2 3 3.30V 0-7A 1 9 GND2 PWRGD 4 Rev 5/01/06 SP6136 Evaluation Manual Copyright © 2006 Sipex Corporation USING THE EVALUATION BOARD 1) Powering Up the SP6136EB Circuit Connect the SP6136ER1 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 It’s 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 ground collar touching Star GND post – avoid a ground lead on the probe which will increase noise pickup. 3) Using the Evaluation Board with Different Output Voltages While the SP6136ER1 Evaluation Board has been tested and delivered with the output set to 3.30V, by simply changing one resistor, R2, the SP6136ER1 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 = 68.1KΩ and for Vout = 0.80V setting, simply remove R2 from the board. Furthermore, one could select the value of the R1 and R2 combination to meet the exact output voltage setting by restricting R1 resistance range such that 50KΩ ≤ R1 ≤ 100KΩ for overall system loop stability. Note that since the SP6136ER1 Evaluation Board design was optimized for 12V down conversion to 3.30V, changes of output voltage and/or input voltage may alter performance from the data given in the Power Supply Data section. POWER SUPPLY DATA The SP6136ER1 is designed with an accurate 1.5% reference over line, load and temperature. Figure 1 data shows a typical SP6136ER1 Evaluation Board efficiency plot, with efficiencies to 92% and output currents to 7A. Load Regulation in Figure 2 shows only 0.12% change in output voltage from no load to 7A. Figures 3 and 4 show the fast transient response. Start-up corresponding to different load conditions is shown in Figures 5, 6 and 7, where the input current rises smoothly as the soft-start ramp increases. In Figure 8 the hiccup mode gets activated in response to an output dead short circuit condition and will soft-start until the over-load is removed. Figure 9 and 10 show output voltage ripple less than 11mV over complete load range. While data on individual power supply boards may vary, the capability of the SP6136ER1 of achieving high accuracy over a range of load conditions shown here is quite impressive and desirable for accurate power supply design. Rev 5/01/06 SP6136 Evaluation Manual Page 2 of 9 Copyright © 2006 Sipex Corporation 100 90 Efficiency vs Load Current Output Voltage (V) Output Voltage vs Load Current 3.320 3.315 3.310 3.305 3.300 Efficiency (%) 80 70 60 50 40 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Vin=12V Vout=3.3V Vin=12V Vout=3.3V 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Load current (A) Load current (A) Figure 1. Efficiency vs Load Figure 2. Load Regulation Vout (100mV/div) Vout (200mV/div) Vin=12V Vout=3.3V Iout(5A/div) Iout (5A/div) Vin=12V Vout=3.3V Figure 3. Load Step Response: 3.5A->7A Figure 4. Load Step Response: 0->7A Vin Vin Vout SoftStart Vin=12V Vout=3.3V Iout (5A/div) Vout SoftStart Iout(5A/div) Vin=12V Vout=3.3V Figure 5. Start-Up Response: No Load Figure 6. Start-Up Response: 3A Load Vin Vout SoftStart Vout SoftStart Iout(5A/div) Vin=12V Vout=3.3V Ichoke(25A/div) Vin=12V Vout=3.3V Figure 7. Start-Up Response: 7A Load Figure 8. Output Load Short Circuit Rev 5/01/06 SP6136 Evaluation Manual Page 3 of 9 Copyright © 2006 Sipex Corporation Vout Ripple(10mV/div) Vout Ripple(10mV/div) Vin=12V Vout=3.3V Vin=12V Vout=3.3V SW Node SW Node Figure 9. Output Noise at No Load Figure 10. Output Noise at 7A Load INDUCTORS - SURFACE MOUNT Inductance (uH) Inductor Specification Manufacturer/Part No. Series R mOhms Isat (A) Size LxW(mm) Ht.(mm) Inductor Type Shielded Ferrite Core Manufacturer Website www.inter-technical.com 2.2 Inter-Technical SC7232-2R2M 10.4 13.00 7.2x6.6 3.20 CAPACITORS - SURFACE MOUNT Capacitance( Manufacturer/Part No. uF) Capacitor Specification ESR ohms (max) Ripple Current (A) @ 45C Size LxW(mm) Ht.(mm) Voltage (V) 16.0 6.3 Capacitor Type X5R Ceramic X5R Ceramic Manufacturer Website www.TDK.com www.TDK.com 22 100 TDK C3225X5R1C226M TDK C3225X5R0J107M 0.005 0.005 4.00 4.00 3X2 3X2 2.00 2.00 MOSFETS - SURFACE MOUNT MOSFET Specification MOSFET Manufacturer/Part No. RDS(on) ohms (max) ID Current (A) Qg nC (Typ) nC (Max) Voltage (V) 30.0 30.0 SO-8 SO-8 Foot Print Manufacturer Website www.vishay.com www.vishay.com N-Ch N-Ch VISHAY Si4354DY VISHAY Si4886DY 18.50 13.5 9.0 11.0 7.0 14.5 10.5 20.0 Table 1: SP6136EB Suggested Components and Vendor Lists Rev 5/01/06 SP6136 Evaluation Manual Page 4 of 9 Copyright © 2006 Sipex Corporation LOOP COMPENSATION DESIGN The open loop gain of the SP6136EB can be divided into the gain of the error amplifier GAMP(S), PWM modulator GPWM, buck converter output stage GOUT(S), and feedback resistor divider GFBK. In order to crossover at the selected frequency fc, the gain of the error amplifier has to compensate for the attenuation caused by the rest of the loop at this frequency. The goal of loop compensation is to manipulate the open loop frequency response such that its gain crosses over 0dB at a slope of –20dB/dec. The open loop crossover frequency should be higher than the ESR zero of the output capacitors but less than 1/5 of the switching frequency fs to insure proper operation. Since the SP6136EB is designed with ceramic type output capacitors, a Type III compensation circuit is required to give a phase boost of 180° in order to counteract the effects of the output LC under damped resonance double pole frequency. Figure 11. SP6136EB Voltage Mode Control Loop with Loop Dynamic Rev 5/01/06 SP6136 Evaluation Manual Page 5 of 9 Copyright © 2006 Sipex Corporation The simple guidelines for positioning the poles and zeros and for calculating the component values for Type III compensation are as follows: R1 = 68.1K R2 = 0.8 × R1 Vout − 0.8 (sets output voltage) CZ 3 = 1 ZSF × R1 × 1 LC 2 (sets first zero) RZ 2 = ((6.28 × fc ) 1 × L × Cout + 1 Vramp × (sets the cross-over frequency, fc) 6.28 × fc × CZ 3 Vin ) CZ 2 = ZSF × RZ 2 × 1 LC (sets second zero) CP1 = 1 (sets first high-frequency pole) 6.28 × fs × RZ 2 1 (sets second high-frequency pole) 6.28 × fs × CZ 3 RZ 3 = Where ZSF=(f compensation double zero)/(f circuit double pole) Here ZSF is set at 0.8. As a particular example, consider for the following SP6136EB, 7AMAX with a type III Voltage Loop Compensation component selections: Vin = 12V Vout = 3.30V @ 0 to 7A load Select L = 2.2 uH => 30% current ripple. Select Cout = 100uF Ceramic capacitor (Resr ≈ 5mΩ) fs = 600KHz SP6136ER1 internal Oscillator Frequency Vramp_pp = 1.0V SP6136ER1 internal Ramp Peak to Peak Amplitude Rev 5/01/06 SP6136 Evaluation Manual Page 6 of 9 Copyright © 2006 Sipex Corporation Step by step design procedures: a. b. c. d. e. f. g. h. R2 = 21.8kΩ CZ3 = 272pF Let fc =80kHz then: RZ2 = 34.4kΩ CZ2 = 538pF CP1 = 7.7pF RZ3 = 0.97kΩ CF1 = 22pF to stabilize SP6136ER1 internal Error Amplify The above component values were used as a starting point for compensating the converter and after laboratory testing the values shown in circuit schematic of page 1 were used for optimum operation. Figure 12- Gain/Phase measurement of SP6136EB shown on page 1, cross-over frequency (fc) is 85KHz with a corresponding phase of 65 degrees Rev 5/01/06 SP6136 Evaluation Manual Page 7 of 9 Copyright © 2006 Sipex Corporation PCB LAYOUT DRAWINGS Figure 13. SP6136EB Component Placement Figure 14. SP6136EB PCB Layout Top Side Figure 15. SP6136EB PCB Layout Bottom Side Rev 5/01/06 SP6136 Evaluation Manual Page 8 of 9 Copyright © 2006 Sipex Corporation Figure 16. SP6136EB PCB Layout Inner Layer 1 & Inner Layer 2 Table 2: SP6136EB List of Materials Line No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Ref. Des. PCB U1 MT MB L1 DBST C1, CBST, CS CSP CIN COUT CVCC C2 CSS CP1 CZ2 CF1 CZ3 R1 R2 R3, R4 R5 RZ2 RZ3 RS1, RS2 RS3 J1 (J1) VIN, VOUT, VCC, GIN, GO, GND, SS, PWRGD, UVIN Qty. 1 1 1 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 Manuf. Sipex Sipex Vishay Semi Vishay Semi Inter-Technical Vishay Semi TDK TDK TDK TDK TDK TDK TDK TDK TDK TDK TDK Panasonic Panasonic Not populated Panasonic Panasonic Panasonic Panasonic Panasonic Sullins Sullins Manuf. Part Number 146-6610-00 SP6136ER1 Si4354DY Si4886DY SC7232-2R2M SD101AWS C1608X7R1C104K C1608JB1H682K C3225X5R1C226M C3225X5R0J107M C2012X5R1A475K C1608X7R1E103J C1608X7R1E473K C1608CH1H120J C1608CH1H561J C1608CH1H220J C1608CH1H271J ERJ-3EKF6812V ERJ-3EKF2152V ERJ-3EKF1002V ERJ-3EKF3092V ERJ-3EKF1001V ERJ-3EKF5111V ERJ-3EKF2002V PTC36SAAN STC02SYAN Layout Size 1.175"x1.934" QFN-16 SO-8 SO-8 7.2x6.6mm 1.5x4.6mm 0603 0603 1210 1210 0805 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 .32x.12 .2x.1 Component SP6136EB Synchronous Buck Controller NFET, 30V, 18.5mOhm NFET, 30V, 13.5mOhm 2.2uH Coil 13A 10.4mOhm Schottky, 60V 0.1 uF Ceramic X5R 16V 6.8nF Ceramic X5R 50V 22uF Ceramic X5R 16V 100uF Ceramic X5R 6.3V 4.7uF Ceramic X5R 10V 0.01uF Ceramic X7R 25V 47nF Ceramic X7R 25V 12pF Ceramic COG 50V 560pF Ceramic COG 25V 22pF Ceramic COG 50V 270pF Ceramic COG 50V 68.1K Ohm Thick Film Res 1% 21.5K Ohm Thick Film Res 1% 10.0K Ohm Thick Film Res 1% 30.9K Ohm Thick Film Res 1% 1K Thick Film Res 1% 5.11K Ohm Thick Film Res 1% 10K Ohm Thick Film Res 1% 36-Pin (3x12) Header Shunt Vendor Phone Number 978-667-7800 978-667-7800 402-563-6866 402-563-6867 914-347-2474 402-563-6866 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 978-779-3111 800-344-4539 800-344-4539 800-344-4539 800-344-4540 800-344-4539 800-344-4540 800-344-4541 800-344-4539 800-344-4539 28 9 Vector Electronic K24C/M .042 Dia Test Point Post 800-344-4539 ORDERING INFORMATION Model Temperature Range Package Type SP6136EB..…...........................− 40°C to +85°C.............……..SP6136 Evaluation Board SP6136ER1............................. − 40°C to +85°C.....................................…….16-pin QFN Rev 5/01/06 SP6136 Evaluation Manual Page 9 of 9 Copyright © 2006 Sipex Corporation