SP6136_06 SIPEX | Alldatasheet
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Rev 5/01/06 SP6136 Evaluation Manual Copyright © 2006 Sipex Corporation SP6136EB SCHEMATIC SS GL SP6136 GL 1 GND 3 PGND 2 VFB 4 ISN 9 ISP 10 SWN 11 GH 12 COMP 5 EN 6 PWRGD 7 SS 8 BST 13 VIN 14 UVIN 15 VCC 16 DIEPAD 17 CF1 22pF 10V RS3 10K1% RS2 5.11k,1% ISN Inter-Technical SC7232-2R2 2.2uH, 10.4 mOhm 0.01uF SWN VFB PTC36SAAN 12V 3.30V 0-7A VCC CP1 12pF ISP A GND UVIN PWRGD EN CSP 6.8nF SS DBST 10.0k,1% Ci 22uF 16V 1210 Co 100uF CIN & COUT CERAMIC 1210 X5R NP All resistors & capacitors size 0603 unless other wise specified RZ3 1K 1% 6.3V 1210 NP CZ3 270pF VIN VOUT 0.1uF 68.1k,1% GND GND2 SD101AWS CZ2 560pF CBST 0.1uF Note: RZ2 30.9K,1% 21.5k,1% CSS 47nF GH RS1 5.11k,1% CS 0.1uF CVCC 4.7uF MT Si4354DY 18.5mOhm 21 3 578 MB Si4886DY 13.5mOhm 21 3 578 VCC SP6136 (7A MAX.) Evaluation Board Manual /square4 Easy Evaluation for the SP6136ER1 12V Input, 0 to 7A Output Synchronous Buck Converter /square4 Precision 0.80V ±1% High Accuracy Reference /square4 Small form factor /square4 Feature Rich: Single supply operation, Over- current protection with auto-restart, Power Good Output, Enable input, Fast transient response, Short Circuit Shutdown Protection, Programmable soft start /square4 TSSOP Package & SMT components for small, low profile Power Supply
Rev 5/01/06 SP6136 Evaluation Manual Copyright © 2006 Sipex Corporation Page 2 of 9 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. Where R1 = 68.1K Ω 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 50K Ω ≤ R1 ≤ 100K Ω 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.
Figure 9. Output Noise at No Load Figure 10. Output Noise at 7A Load
2.2 Inter-Technical
MOSFET Manufacturer/Part No.
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 Copyright © 2006 Sipex Corporation Page 6 of 9 The simple guidelines for positioning the poles and zeros and for calculating the component values for Type III compensation are as follows: KR 1 .68 1 = 8.0 18 . 02 − ×= Vout RR (sets output voltage) LC RZSF CZ 11 = (sets first zero) ( )( ) Vin Vramp CZ fc Cout Lfc RZ ××× +×××= 328 . 6 128 . 62 (sets the cross-over frequency, fc) LC RZ ZSF CZ 12 = (sets second zero) 228 . 6
11 RZ fs CP ××= (sets first high-frequency pole)
328 . 6
13 CZ fs RZ ××= (sets second high-frequency pole)
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 Copyright © 2006 Sipex Corporation Page 7 of 9 Step by step design procedures a. R2 = 21.8k Ω b. CZ3 = 272pF c. Let fc =80kHz then: d. RZ2 = 34.4k Ω e. CZ2 = 538pF f. CP1 = 7.7pF g. RZ3 = 0.97k Ω h. 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 Copyright © 2006 Sipex Corporation Page 9 of 9 Figure 16. SP6136EB PCB Layout Inner Layer 1 & Inner Layer 2
2 U1 1 Sipex SP6136ER1 QFN-16 Synchronous Buck Controller 978-667-7800
3 MT 1 Vishay Semi Si4354DY
9 CIN 1 TDK C3225X5R1C226M 1210 22uF Ceramic X5R 16V 978-779-3111
13 CSS 1 TDK C1608X7R1E473K 0603 47nF Ceramic X7R 25V 978-779-3111
14 CP1 1 TDK C1608CH1H120J 0603 12pF Ceramic COG 50V 978-779-3111
15 CZ2 1 TDK C1608CH1H561J 0603 560pF Ceramic COG 25V 978-779-3111
16 CF1 1 TDK C1608CH1H220J 0603 22pF Ceramic COG 50V 978-779-3111
17 CZ3 1 TDK C1608CH1H271J 0603 270pF Ceramic COG 50V 978-779-3111
20 R3, R4 Not populated
23 RZ3 1 Panasonic ERJ-3EKF1001V 0603 1K Thick Film Res 1% 800-344-4539
25 RS3 1 Panasonic ERJ-3EKF2002V 0603 10K Ohm Thick Film Res 1% 800-344- 4541
ORDERING INFORMATION
Model Temperature Range Package Type