SP7651ER-L

SP7651 Solved by Wide Input Voltage Range 3Amp 900kHz Buck Regulator TM FEATURES • 2.5V to 20V Step Down Achieved Using Dual Input • Output Voltage down to 0.8V • 3A Output Capability (Up to 5A with Air Flow) • Built in Low RDSON Power FETs (40 mΩ typ) • Highly Integrated Design, Minimal Components • 900 kHz Fixed Frequency Operation • UVLO Detects Both VCC and VIN • Over Temperature Protection • Short Circuit Protection with Auto-Restart • Wide BW Amp Allows Type II or III Compensation • Programmable Soft Start • Fast Transient Response • High Efficiency: Greater than 92% Possible • Asynchronous Start-Up into a Pre-Charged Output • Small 7mm x 4mm DFN Package • U.S. Patent #6,922,041 SP7651 DFN PACKAGE 7mm x 4mm LX 26 LX 25 LX 24 LX 23 BOTTOM VIEW 1 PGND Heatsink Pad 1 Connect to Lx 2 PGND 3 PGND Pin 27 VCC 22 GND 21 GND 20 GND 19 BST Heatsink Pad 2 Connect to GND 4 GND 5 VFB 6 COMP 7 UVIN 8 GND 18 9 SS NC 17 10 VIN LX 16 11 VIN LX 15 LX 14 Pin 28 Heatsink Pad 3 Connect to VIN Pin 29 12 VIN 13 VIN So DESCRIPTION The SP7651 is a high voltage synchronous step-down switching regulator optimized for high efficiency. The part is designed to be especially attractive for dual supply, 12V step down with 5V used to power the controller. This lower VCC voltage minimizes power dissipation in the part. The SP7651 is designed to provide a fully integrated buck regulator solution using a fixed 900kHz frequency, PWM voltage mode architecture. Protection features include UVLO, thermal shutdown and output short circuit protection. The SP7651 is available in the space saving 7mm X 4mm DFN package. TYPICAL APPLICATION CIRCUIT U SP7651  Rz2 Cz2 2 3 ,000pF 5k,1% 4 CP 5 22pF CF 6 ENABLE 00pF 7 8 9 CSS 5nF 0  2 3 VIN 12V C Rev J: 3/14/07 LX PGND LX PGND LX GND LX VFB VCC COMP GND UVIN GND GND GND SS BST VIN NC VIN LX VIN LX VIN LX L 26 25 4.7uH, Irate=3.87A +5V VCC 24 23 22 2 20 CVCC DBST 8 6 5 4 C3 22uF 6.3V 7.5kΩ, 1% Cz3 VOUT 3.3V 0-3A R 68.kΩ,% 50pF 2.2uF 9 7 Rz3 SD101AWS CBST RSET 2.5kΩ,% (note 2) 6800pF fs=900Khz 22uF 16V GND PGND Notes: 1. U1 Bottom-Side Layout should have three contacts isolated from one another: Vin, SWNODE, and GND. 2. RSET=54.48/(Vout-0.8V) (KOhm) SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator  © Copyright 2007 Sipex Corporation ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. All other pins.............................................................-0.3V to VCC+0.3V VCC .................................................................................................. 7V VIN.................................................................................................. 22V ILX..................................................................................................... 5A BST................................................................................................. 35V LX-BST................................................................................-0.3V to 7V LX.........................................................................................-1V to 20V Storage Temperature.................................................... -65°C to 150°C Power Dissipation...................................................... Internally Limited ESD Rating............................................................................ 2kV HBM Thermal Resistance ΟJC. .......................................................... 5°C/W ELECTRICAL CHARACTERISTICS Unless otherwise specified: -40°C < TAMB < 85°C, -40°C< Tj Rz3 Output Load Resistance >> R ESR & R DC Voltage Feedback G FBK Gain Block R2 V FBK (Volts) (R 1 + R 2 ) or V REF V OUT SP7651 Voltage Mode Control Loop with Loop Dynamic Definitions: RESR = Output Capacitor Equivalent Series Resistance RDC = Output Inductor DC Resistance RRAMP_PP = SP7651 internal RAMP Amplitude Peak-to-Peak Voltage Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator  © Copyright 2007 Sipex Corporation APPLICATIONS INFORMATION Gain (dB) Error Amplifier Gain Bandwidth Product Condition: C22 >> CP1, R1 >> RZ3 1/6.28(RZ3) (CZ3) 1/6.28(RZ2) (CP1) 1/6.28(R1) (CZ2) 1/6.28(R1) (CZ3) 1/6.28(R22) (CZ2) 20 Log (RZ2/R1) Frequency (Hz) Bode Plot of Type III Error Amplifier Compensation. CP1 RZ3 CZ3 CZ2 V OUT R1 68.1k, 1% 5 VFB R SET + + - 0.8V R SET RZ2 6 COMP CF1 =54.48/ (V OUT -0.8) (kΩ) Type III Error Amplifier Compensation Circuit Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 10 © Copyright 2007 Sipex Corporation APPLICATIONS INFORMATION data was taken for still air, not with forced air. If forced air is used, some improvement in thermal resistance would be seen. SP765X Thermal Resistance The SP765X family has been tested with a variety of footprint layouts along with different copper area and thermal resistance has been measured. The layouts were done on 4 layer FR4 PCB with the top and bottom layers using 3oz copper and the power and ground layers using 1oz copper. SP765X Thermal Resistance For the Minimum footprint, only about 0.1 square inch of 3 ounces of copper was used on the top or footprint layer, and this layer had no vias to connect to the 3 other layers. For the Medium footprint, about 0.7 square inches of 3 ounces of copper was used on the top layer, but vias were used to connect to the other 3 layers. For the Maximum footprint, about 1.0 square inch of 3 ounces of copper was used on the top layer and many vias were used to connect to the 3 other layers. 4 Layer Board: Top Layer 3ounces Copper GND Layer 1ounce Copper Power Layer 1ounce Copper Bottom Layer 3ounces Copper The results show that only about 0.7 square inches of 3 ounces of copper on the top layer and vias connecting to the 3 other layers are needed to get the best thermal resistance of 36°C/W. Adding area on the top beyond the 0.7 square inches did not reduce thermal resistance. Maximum Footprint: 36°C/W Top Layer: 1.0 square inch Vias to other 3 Layers Minimum Footprint: 44°C/W Top Layer: 0.1 square inch No Vias to other 3 Layers Medium Footprint: 36°C/W Top Layer: 0.7 square inch Vias to other 3 Layers Using a minimum of 0.1 square inches of (3 ounces of) Copper on the top layer with no vias connecting to the 3 other layers produced a thermal resistance of 44°C/W. This thermal impedance is only 22% higher than the medium and large footprint layouts, indicating that space constrained designs can still benefit thermally from the Powerblox family of ICs. This indicates that a minimum footprint of 0.1 square inch, if used on a 4 layer board, can produce 44°C/W thermal resistance. This approach is still very worthwhile if used in a space constrained design. The following page shows the footprint layouts from an ORCAD file. The thermal Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 11 © Copyright 2007 Sipex Corporation Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 12 © Copyright 2007 Sipex Corporation TYPICAL PERFORMANCE CHARACTERISITICS Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 13 © Copyright 2007 Sipex Corporation Package: 26 Pin dfn Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 14 © Copyright 2007 Sipex Corporation ORDERING INFORMATION Part Number MIN. Temp. (°C) MAX. Temp.(°C) Status SP7651ER Package Code DFN26 RoHS -40 85 Active Pack Quantity Bulk SP7651ER/TR DFN26 -40 85 Active 500 Tape & Reel SP7651ER-L DFN26 ▪ -40 85 Active Bulk SP7651ER-L/TR DFN26 ▪ -40 85 Active 500 Tape & Reel Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. Rev J: 3/14/07 SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator 15 © Copyright 2007 Sipex Corporation