NCV8842PWGEVB NCV8842 Buck Regulator 7.0 V-16 V to 5.0 V, 3.3 V and 2.5 V @ 1.0 A Evaluation Board User's Manual http://onsemi.com EVAL BOARD USER’S MANUAL Features • V@ Control Method for Uncomplicated Loop Compensation, Fast Transient Response, and Reduced Board Area • A Total of 12 Components, Including the IC, to Realize a Complete Buck Regulator • Shutdown Terminal to Disable the Output and Provide a Low Current Drain Standby Mode • Sync Terminal to Permit Controller Synchronization to an External Source • 1.5 A Peak Inductor Current • Cycle−by−Cycle Frequency−Foldback Current Limiter • Soft Start Function to Reduce Inrush Current • 87% Efficiency at 1 A Load Current (5 V Output) • Line Regulation Better Than 0.02% • Load Regulation Better Than 0.2% Description The NCV8842 Evaluation Boards provide a convenient way to implement and evaluate a complete practical buck regulator design. No additional components are required other than the DC input source and load. Separate boards are available for the SOIC−16 and DFN−18 versions of the device. The SOIC−16 board has an input voltage range of 7 V – 16 V and includes jumpers to set the DC output voltage to 2.5 V, 3.3 V or 5.0 V. The DFN−18 board has an input voltage range of 6 V – 16 V and is preset for a nominal output voltage of 3.3 V. Both boards include SHDNB and SYNC terminals for logic on−off control of the regulator and synchronization of the internal controller to a external frequency source instead of the internal 170 kHz oscillator. BR3 BR2 BR1 VIN C3 C2 GND GND VOUT SHDN L1 SYNC GND Figure 1. NCV8842 Evaluation Board (SOIC Package) © Semiconductor Components Industries, LLC, 2012 May, 2012 − Rev. 3 1 Publication Order Number: EVBUM2118/D NCV8842PWGEVB Table 1. ABSOLUTE MAXIMUM RATINGS Pin Name Maximum Voltage Maximum Current VIN 16 V 2.0 A VOUT 10 V 2.0 A SHDNB 7.0 V 1.0 mA SYNC 7.0 V 1.0 mA Stresses exceeding Maximum Ratings may damage the board. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Table 2. NCV8842 SOIC EVALUATION BOARD USER TERMINALS VIN Positive DC input voltage, 7 V to 16 V GND Common power negative / signal return VOUT Regulated DC output voltage SHDNB Shutdown−bar signal. Leave open or drive high for normal operation, drive low to force the regulator into sleep/shutdown mode. SYNC Input signal to synchronize to converter oscillator to a higher external frequency source. Leave open if unused. BR1, BR2, BR3 Bridges (jumpers) for programming the regulated output voltage to one of three levels. Always bridge one pair of terminals. Terminals bridged VOUT BR1 2.5 V BR2 3.3 V BR3 5.0 V Table 3. ELECTRICAL CHARACTERISTICS (TA = 25°C, 7.0 V ≤ VIN ≤ 16 V, 0.1 A ≤ IOUT ≤ 1.0 A, unless otherwise specified.) Characteristic Test Conditions Typ Unit − 4.0 % Line Regulation No Load 0.02 % Load Regulation VIN = 7.0 V 0.15 % − 3.0 % Load toggle between 0.1 A and 1.0 A 10 μs − 5.0 ms − 3.3 V Sync Frequency − 190 to 355 kHz Minimum Sync Threshold Voltage − 1.0 V Minimum Shutdown Threshold Voltage − 0.3 V Maximum Shutdown Bias Current − 12 mA − 170 kHz ILOAD = 100 mA ILOAD = 1.0 A 77.5 83 % % − 1.0 mA Output Voltage Voltage Accuracy Transient Response Transient Response Time Startup Time Input Voltage Start Threshold Sync and Shutdown General Switching Frequency Efficiency Shutdown Current* *If a pull−up resistor is employed, the shutdown current is increased drastically (Vin/R). http://onsemi.com 2 NCV8842PWGEVB 1 TP1 TP2 SHUTDOWN SYNC R6 10k D1 R5 0 C1 1 mF L1 Vout U1 Vsw SHDNB NC NC NC NC SYNC GND 27 mH BR3 BR2 BR1 C3 100 mF R4 374 R3 205 Vin BOOST NC NC NC NC Vc Vfb NCV8842 D2 + Vin EPAD 1 R1 124 C4 0.1 mF C5 0.1 mF + C2 330 mF R2 127 Figure 2. Application Diagram Operation Guidelines charge across C1. D1 is now reverse−biased, and the energy stored in C1 is used to bias the output stage. 1. Connect a DC input voltage, within the range of 7.0 V to 16 V, between the board terminals “VIN” (+) and “GND” (−). 2. Connect a load impedance between terminals “VOUT” (+) and “GND” (−). 3. To force the regulator into Shutdown/sleep mode, connect the “SHDNB” terminal to a positive DC voltage of 0.3 V or less, or connect it directly to GND. 4. If synchronization to an external frequency source is desired, connect the SYNC terminal to a pulse source with positive amplitude 1 V to 7 V relative to GND. Sync pulse duty cycle may vary from 10% to 90%. 2. Soft Start: The soft−start is implemented on the VC pin. During the startup, the limited source current (25 μA) of the error amplifier charges the VC pin capacitor. The rising slope of the VC pin voltage clamps the duty cycle through the PWM comparator. The VC pin voltage eventually settles down to a voltage roughly equal to the reference voltage 1.27 V. Therefore, the startup time can be easily calculated. 3. Feedback Network: V2 control relies on the output ripple to provide pulse width modulation. When the output ripple is inadequate, pulse skipping or instability may be observed. Adding a capacitor C6 in parallel with R1 provides a low impedance pass for the output ripple. Therefore, the output ripple is not attenuated by the resistor divider. The use of this capacitor is optional. Theory Of Operation 1. Boost Circuit: The Boost circuit, comprised of D1 and C1, generates a voltage higher than the output voltage to drive the base of the internal NPN power switch. When the internal power switch is Off, pin Vsw of the NCV8842 goes negative to sustain the current in L1 through Schottky diode D2. Diode D1 is forward biased, and charges C1 to approximately the output voltage. When the internal power switch turns on, Vsw is driven high, forcing the voltage at BOOST to be the sum of the instantaneous voltage at Vsw plus the Please see data sheet for more description on regulator operation and component selection (document number NCV8842/D available through the Literature Distribution Center or via our website at http://www.onsemi.com). http://onsemi.com 3 NCV8842PWGEVB TYPICAL PERFORMANCE CHARACTERISTICS 5.0391 90 5.0389 5.0388 5.0387 VOUT 5.0386 5.0385 5.0384 5.0383 3.3 V 80 75 2.5 V 70 65 60 5.0382 55 5.0381 5.0380 5.0 V 85 EFFICIENCY (%) OUTPUT VOLTAGE (V) 5.0390 7 8 9 10 11 12 13 14 15 50 16 0 0.2 0.4 0.6 0.8 INPUT VOLTAGE (V) OUTPUT CURRENT (A) Figure 3. Line Regulation Figure 4. Efficiency vs. Output Current http://onsemi.com 4 1.0 NCV8842PWGEVB Figure 5. Continuous Mode Operation Figure 6. Discontinuous Mode Operation Figure 7. 300 mA to 1.0 A Load Step (3.3 V) Figure 8. 1.0 A to 300 mA Load Release (3.3 V) Figure 9. Overall 600 mA Load Response http://onsemi.com 5 NCV8842PWGEVB Table 4. BILL OF MATERIALS Ref. Designator Vendor Part Number Type PC/Board C1 Panasonic ECJ−1VB0J105K 1 mF Ceramic 1 C2 Panasonic EEVEC1V331P 330 mF Electrolytic 1 C3 AVX TAJE107K016R 100 mF Tantalum 1 C4, C5 Panasonic ECJ−1VBIC104K 0.1 mF Ceramic 2 D1 ON Semiconductor MBRM130LT3 Diode (Fast Switching) 1 D2 ON Semiconductor MBRS240T3 2A Diode (Schottky) 1 R1 Panasonic ERJ−3EKF2040V 124 W Resistor 1 R2 Panasonic ERJ−3EKF1270V 127 W Resistor 1 R3 Panasonic ERJ−3EKF205V 205 W Resistor 1 R4 Panasonic ERJ−3EKF3740V 374 W Resistor 1 R5 Panasonic ERJ−2GEY100V 10 W Resistor 1 R6 Panasonic ERJ−2GEY103V 10 kW Resistor 1 L1 Wurth 744771127 27 mH Inductor 1 U1 ON Semiconductor NCV8842 Controller 1 J1−J8 Vector K24C/M Test Points 8 BR1, 2, 3 Molex/Moldom 22−28−4020 Jumpers 3 http://onsemi.com 6 NCV8842PWGEVB DRAWINGS OF LAYERS Figure 10. Top Copper Figure 11. Bottom Copper Figure 12. Top Silk http://onsemi.com 7 NCV8842PWGEVB DFN EVALUATION CIRCUIT INFORMATION GND VIN (6V − 16V) C4 C2 VOUT (3.3V) GND L1 SHDN SYNC GND Figure 13. NCV8842 Evaluation Board (DFN Package) TP5 1 VIN R3 100k D1 L1 27uH EPAD TP4 BOOST Vin Vin Vin Vsw Vsw Vsw SHDNB NC C1 1uF 1 Vout C4 + 100uF TP7 R1 205 C6 3nF D2 NC Vc Vfb NC NC GND NC NC SYNC C2 330uF C5 0.1uF U1 C3 0.1uF R2 127 1 GND TP6 TP1 SHDNB 1 1 1 1 TP3 GND Figure 14. Application Diagram http://onsemi.com 8 TP2 SYNC GND NCV8842PWGEVB Table 5. BILL OF MATERIALS Ref Des Type Part Number Vender PC/Board C3, C5 0.1 mF Ceramic PCC2398CT−ND Panasonic 2 C1 1.0 mF Ceramic ECJ−1VBOJ105K Panasonic 1 C2 330 mF Electrolytic MZA35VC331MJ10TP United Chemi−Con 1 C4 100 mF Tantalum TPSC107K010R0075 AVX 1 C6 3.0 nF Ceramic Not Used D1 Diode MBRM130LT1G ON Semiconductor 1 D2 2 A Schottky Diode MBRS240LT3G ON Semiconductor 1 L1 27 mH 7447779127 Wurth 1 R1 205 W Resistor P205HCT−ND Panasonic 1 R2 127 W Resistor P127HCT−ND Panasonic 1 R3 100 kW Resistor P100kHCT−ND Panasonic 1 J1, J2, J4−J8 Test Points 2501−2−00−44−00−00−07−0 Mill−Max MFG 7 J3 Test Point (Vsw) K24C/M Vector 1 U1 Regulator NCV8842G ON Semiconductor 1 http://onsemi.com 9 1 NCV8842PWGEVB DRAWING OF LAYERS (DFN) Figure 15. Top Copper Figure 16. Bottom Copper Figure 17. Top Silk http://onsemi.com 10 NCV8842PWGEVB V2 is a trademark of Switch Power, Inc. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). 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