IRDC3651 USER GUIDE FOR IR3651 EVALUATION BOARD DESCRIPTION The IR3651 is a high voltage PWM controller designed for high performance synchronous Buck DC/DC applications. The IR3651 drives a pair of external NMOSFETS using a programmable switching frequency up to 400kHz allows flexibility to tune the operation of the IC to meet system level requirements, and synchronization allows the simplification of system level filter design. The output voltage can be precisely regulated using the internal 1.25V reference voltage for low voltage applications. Protection functions such as under voltage lockout and hiccup current limit are provided to give required system level security in the event of fault conditions. This user guide contains the schematic and bill of materials for the IR3651 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for the IR3651 integrated circuit is available in the IR3651 data sheet. Evaluation Board Specifications: VIN = 48V, tolerance 10% VOUT = 3.3V at 10A FS = 100kHz CONNECTIONS J2: VIN = 48V J3: VOUT = 3.3V J4, J7: GROUND J5: Shutdown control input J6: Sync input J1: External 12V supply option. Rev 1.1 12/20/2006 RD-0616 1 IRDC3651 CONNECTION DIAGRAM 48V Power Supply Load: 3.3V@ 0A to 10A Note: Ground connection pads are located on the bottom side of the circuit board. Figure 1 – Connections to IR3651 evaluation board for default configuration . Rev 1.1 12/20/2006 RD-0616 2 IRDC3651 CIRCUIT LAYOUT - TOP LAYER The PCB is a 4-layer FR4 board. The IR3651 IC and the associated passive components are mounted on the top side of the board. Solder pads for off-board connections to various power supply options and control signals are placed on the top layer. Off-board connections to ground are available on the bottom layer. Power supply decoupling capacitors, the charge pump capacitor and feedback components are located close to the IR3651 IC. The feedback resistors are connected to the output voltage at the point of regulation and are located close to the IC. Two different MOSFET configurations can be used: eight-pin SOIC packages on the top side of the board or MX-packaged DirectFets on the bottom side of the board. The bottom–side location of the DirectFet packages allows convenient mounting of heat sinking devices The input and output energy storage capacitors and the power inductor are placed close to the MOSFET packages. To improve efficiency, the circuit board is designed to minimize the length of the onboard power ground current path. Two alternatives are provided for implementation of the required single point of connection between Signal Ground and Power ground. Install a zero ohm resistor at location R10 to implement the shortest available connection between the grounds. Installation of R10 is the minimum–noise solution and is the default. If R10 is removed and R9 is installed, an approximation of remote voltage sensing is available. Remote sensing will minimize voltage error due to ground currents, but may be more vulnerable to high-frequency noise. Either R9 or R10 (default) must be installed to implement the required single point of connection between Signal Ground and Power Ground. Figure 2 – Top layer of the IR3651 evaluation board. Rev 1.1 12/20/2006 RD-0616 3 IRDC3651 CIRCUIT LAYOUT- BOTTOM LAYER Solder pads for off-board connections ground are available on the bottom layer. A portion of the bottom layer plane is isolated for use as Signal Ground. Options for making the required single point of connection between Signal ground and Power Ground are provided on the top side of the board. The IR3651 controller requires a low voltage power source (nominally 12V). Elements of a simple linear voltage regulator are installed on a circuit pattern provided on the bottom layer to generate the required voltage from the 48V input supply. MX-packaged DirectFets can be mounted on the bottom side of the board. The bottom–side location of the DirectFet packages allows convenient attachment of a heat sink. Alternatively, a separate external 12V supply can be connected at J12, on the top side of the board. Low Voltage Linear Regulator Components Off - board Ground Connection Pads DirectFet Positions Heat Sink mounting area (optional) Signal Ground Plane Figure 3 – Bottom layer of the IR3651 evaluation board. Rev 1.1 12/20/2006 RD-0616 4 IRDC3651 LAYOUT -- MID-LAYERS The two mid-layers are used primarily for Power Ground. Mid-layer 1 Mid-layer 2 Figure 3 – Internal layers of IR3651 evaluation board. Rev 1.1 12/20/2006 RD-0616 5 Figure 4 – Schematic of the IR3651 evaluation board IRDC3651 Rev 1.1 12/20/2006 RD-0616 6 IRDC3651 BILL OF MATERIALS Quantity 1 1 1 1 1 1 6 3 1 1 1 1 1 1 1 1 1 2 2 3 2 1 1 5 2 4 3 1 5 1 1 2 Designator U1 Q1B Q2B D1 D23 ROCSet RT1, RT2, RT3, RT4, RT5, RT6 R6, 10, 20 R11 R3 R4 R2 R1 R5 C10 C9 C7 C4, 6 C3, 5 C1A, C1B, C1C C8A, C8B L1 Circuit board R7, 8, 9, 21, 22, 23 RT7, RT8 C1, 2, 8, 21 C1D, C1E, C1F C8C C5A, C5B, C20A, C20B, C20C D22 QT Q1A, Q2A Value 1 * * * * 12V 19.1k Value 2 * * * * 230mW 1/8W Tolerance * * * * * 1% Description 1 IC MOSFET MOSFET DIODE Zener Diode RESISTOR Description 2 PWM Controller POWER NFET POWER NFET Silicon PN * thick film Package SOIC-14 DirectFET DirectFET SOT-23 SOT-23 0805 Source IR IR IR ON Diodes Inc. Panasonic-ECG Source Part No. IR3651 IRF6662 IRF6646 MMBD6100LT1 BZX84C12-7-F ERJ-6ENF1912V 2.43k 1/4W 1% RESISTOR thick film 1206 Panasonic-ECG ERJ-8ENF2431V 0 Ohm 665 Ohm 1.5k 4.99k 17.4k 28.7k 255k 220pF 2.2nF 18nF 0.1uF 1uF 1/8W 1/8W 1/8W 1/8W 1/8W 1/8W 1/8W 50V 50V 50V 25V 16V 1% 1% 1% 1% 1% 1% 1% 5% 5% 5% 10% 10% RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR thick film thick film thick film thick film thick film thick film thick film C0G (NP0) C0G (NP0) C0G (NP0) X7R X5R 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 Panasonic-ECG Panasonic-ECG Panasonic-ECG Panasonic-ECG Panasonic-ECG Panasonic-ECG Panasonic-ECG KEMET MURATA MURATA YAEGO Panasonic-ECG ERJ-6ENF0R00V ERJ-6ENF6650V ERJ-6ENF1501V ERJ-6ENF4991V ERJ-6ENF1742V ERJ-6ENF2872V ERJ-6ENF2553V C0805C221J5GACTU GRM2165C1H222JA01D GRM21B5C1H183JA01L CC0805KRX7R8BB104 ECJ-2FB1C105K 2.2uF 100V * CAPACITOR X7R 1210 MURATA GRM32ER72A225K 330uF 6.8uH * 6V * * * * * CAPACITOR INDUCTOR PCB POSCAP * Rev_11 * 0.5 x 0.5 * SANYO ACT IR 6TPD330M STS1305-6R8M DB513 UNUSED * * * * 0805 * * UNUSED UNUSED * * * * * * * * 1206 0805 * * * * UNUSED * * * * 1210 * * UNUSED * * * * * * * UNUSED * * * * 1210 * * UNUSED UNUSED UNUSED * * * * * * * * * * * * SOT-23 SOT-223 SO-8 * * * * * * db513_11-IR3651_48V-Buck-3.3V_Eval_Board_BOM_Rev1.42.xls Rev 1.1 12/20/2006 RD-0616 7 IRDC3651 TYPICAL Output WAVEFORMS Vin=48V, Vo=3.3V, Room Temperature, No Air Flow 0A load Cyan: VIN Blue: VOUT Green: IOUT 10A load Figure 5 – Startup waveforms Rev 1.1 12/20/2006 RD-0616 8 IRDC3651 TYPICAL Output WAVEFORMS Vin=48V, Vo=3.3V, Room Temperature, No Air Flow Figure 6 – 0A to 10A Transient Blue: VOUT Green: IOUT Figure 7 – Output Ripple, 10A load Rev 1.1 12/20/2006 RD-0616 9 IRDC3651 TYPICAL Output WAVEFORMS Vin=48V, Vo=3.3V, Room Temperature, No Air Flow Short Circuit : Operation and Recovery Blue: VOUT Green: IOUT Magenta: VSS Short Circuit : Detail of “Hiccup” Figure 8 – Short Circuit Response Rev 1.1 12/20/2006 RD-0616 10 IRDC3651 TYPICAL Output WAVEFORMS Vin=48V, Vo=3.3V, Room Temperature, No Air Flow 0A Load Blue: VOUT Cyan: VIN Green: IOUT Magenta: VSS 10A Load Figure 9 – Shutdown Rev 1.1 12/20/2006 RD-0616 11 IRDC3651 TYPICAL Output WAVEFORMS Vin=48V, Vo=3.3V, Room Temperature, No Air Flow Figure 10 – Efficiency Rev 1.1 12/20/2006 RD-0616 12 IRDC3651 Vin=48V, Vo=3.3V, 10A Load, Room Temperature, No Air Flow (1) IR5651 Controller (2) Inductor (3) Output Capacitors Figure 11a – Temperature Distribution, Top side (1) IRF6646 Sync-Rectifier FET (2) IRF6662 Switch FET (3) 12V linear supply resistor Figure 11b – Temperature Distribution, bottom side Rev 1.1 12/20/2006 RD-0616 13