www.fairchildsemi.com FEB207-021 User Guide FAN2103 TinyBuckTM Integrated Synchronous Buck Evaluation Board Featured Fairchild Product: FAN2103 www.fairchildsemi.com/FEBsupport (c) 2008 Fairchild Semiconductor Corporation 1 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com Table of Contents 1. Overview................................................................................................................................... 3 2. Board Configuration ................................................................................................................. 3 3. Power-Up Sequence.................................................................................................................. 3 4. Board Features .......................................................................................................................... 4 4.1. 4.2. 4.3. 4.4. 4.5. 4.6. 4.7. 4.8. 4.9. Switching Waveform ...................................................................................................... 4 Enable / Inhibit................................................................................................................ 4 Current Limit .................................................................................................................. 4 Auto-Restart.................................................................................................................... 4 Switching Frequency....................................................................................................... 4 Input Voltage................................................................................................................... 4 Output Voltage................................................................................................................ 5 Feedback Loop Response................................................................................................ 5 Connections..................................................................................................................... 5 5. Schematics ................................................................................................................................ 6 6. Bill of Materials ........................................................................................................................ 7 7. Assembly Diagram.................................................................................................................... 8 8. PCB Layout............................................................................................................................... 8 (c) 2008 Fairchild Semiconductor Corporation 2 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com This guide supports the evaluation kit for the FAN2103 TinyBuckTM Integrated Synchronous Buck. This guide should be used in conjunction with the FAN2103 datasheet, located at Fairchild's website (www.fairchildsemi.com). 1. Overview This board provides 1.8VOUT and 0-3A from 8-20VIN at a 500KHz switching rate using low-cost ceramic output capacitors. Figure 1. Evaluation Board and Required Connections 2. Board Configuration 3. Output Voltage: Output Current: Input Voltage: Frequency: 1.8V 0-3A 8-20V 500KHz Power-Up Sequence 1. Establish connections to test equipment as shown in Figure 1. Use suitable diameter wires and connectors to avoid excessive voltage drop or temperature rise. Do not turn on power supplies until all the connections are complete. 2. Verify voltage sources have current limits adequately set to supply the load. 3. Apply VIN before VCC to avoid skipping the soft-start cycle. 4. Apply the desired load current. This can be done at any time, including before power-up, but it is recommended to power-up the first time with 0A load to verify proper connections. To power down, turn off the VCC (5V) supply first. (c) 2008 Fairchild Semiconductor Corporation 3 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com 4. Board Features A ground strap is provided near the lower-left corner of the evaluation board to facilitate oscilloscope probe connections. 4.1. Switching Waveform Connect an oscilloscope probe to test point marked SW to view the switching waveform. Since the MOSFETs are integrated, gate/drive waveforms cannot be viewed. 4.2. Enable / Inhibit The momentary push-button switch S1 establishes a connection from EN to GND, inhibiting the FAN2103 when switching ceases and only standby current is consumed. A new soft-start cycle commences upon release of S1. 4.3. Current Limit The current limit threshold can be set lower by reducing R9. This feature is useful in applications where <3A is required, allowing the designer to select passive external components with lower current ratings. With R9 open, the FAN2103 enforces a maximum default current limit in excess of 3A. 4.4. Auto-Restart The board is configured for auto-restart with a delay (C7) that increases linearly with C7. Refer to the datasheet for auto-restart or latch-off options. 4.5. Switching Frequency Switching frequency is set by R10 (RT). Frequency may be lowered to 200KHz or raised to >600KHz. Large changes in frequency may warrant additional component value changes for the output filter and compensation network. 4.6. Input Voltage The demo board is optimized to work with an 8V to 20V input voltage range. For operating between 3V to 8V, modifications to output filter, compensation network component values, and R7 need to be made. (c) 2008 Fairchild Semiconductor Corporation 4 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com 4.7. Output Voltage The output voltage is determined by the ratio of R1 and R4. For minor output voltage changes, adjust R4. Larger VOUT changes may impact output filter and compensation network component value selection. 4.8. Feedback Loop Response R5 opens the feedback loop for closed-loop response measurement. Remove R5 and connect a network analyzer or injection transformer in its place. 4.9. Connections Be clear about order of connections, notes or cautions, etc. Include step-by-step, numbered instructions. (c) 2008 Fairchild Semiconductor Corporation 5 FEB207_FAN2103 * Rev. 0.2.1 (c) 2008 Fairchild Semiconductor Corporation 5V_RTN AGND C5 1.0u VCC PGOOD 6 SW1 3.3n C7 R10 28.7K R9 200K R2 2.49K 4.7n C3 4.7n C2 R12 20K 62 0 R3 R5 SPG50 FAN2103 AGND FB COMP R1 16 19 20 ILIM EN RT VCC PGOOD 2.49K R4 2K FB C1 56p COMP 17 14 18 15 13 U1 CLK/FPWM GND GND GND GND SW SW SW SW SW SW SW SW BOOT RAMP VIN PIN2 VIN VIN VIN P3 21 22 23 P1 6 7 8 9 10 11 12 1 25 P2 2 3 4 5 SW R7 200K VIN VOUT C4 0.1u R13 0 390p C6 1.5 R6 SW BOOT L1 3.3u C9 22u C10 22u C8 3.3n C11 22u C14 4.7u C12 22u C15 4.7u VOUT C16 4.7u J2_ 1 2 1 2 J2+ J1_ 1 2 1 2 J1+ GND VOUT GND VIN 5. +5V PGOOD NC 24 www.fairchildsemi.com Schematics Figure 2. FAN2103 Evaluation Board Schematic FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com 6. Bill of Materials U1 1 IC, FAN2103, MLP5x6 Fairchild FAN2103M L1 1 3.3H, 5.4A, 18m Cooper DR74-3R3-R R1, 2 2 2.49K, 1%, 0603 DigiKey P2.49K H R3 1 62, 5%, 0603 DigiKey P62 G R4 1 2.00K, 1%, 0603 DigiKey P2.00K H R5, 13 3 0, 5%, 0603 DigiKey P0.0 G R6 1 1.5, 5%, 0805 DigiKey P1.5 A R7, 9 2 200K, 1%, 0603 DigiKey 200K H R10 1 30.1K, 1%, 0603 DigiKey P30.1K H R12 1 10K, 5%, 0603 DigiKey P10K G C1 1 56pf, 50V, 5%, NPO, 0603 DigiKey PCC560ACV C2, 3 2 4.7nf, 50V, 10%, X7R, 0603 DigiKey PCC1780 C7, 8 2 3.3nf, 50V, 10%, X7R, 0603 DigiKey PCC1778 C4 1 0.1f, 16V, 10%, X7R, 0603 DigiKey PCC1762 C5 1 1.0f, 10V, 10%, X5R, 0805 DigiKey PCC1807 C6 1 390pf, 50V, 10%, X7R, 0603 DigiKey PCC391BV C9, 10, 11, 12 4 22f, 6.3V, 20%, X5R, 1206 DigiKey PCC2242 C14, 15, 16 3 4.7f, 25V, 20%, X5R, 1206 DigiKey PCC2241 J1+, J1-, J2+, J2- 4 Connector, QDM, 0.25", Right Angle DigiKey 4966K SW1 1 Switch, 1 pole, momentary push DigiKey EG2513 +5V 1 Test Point, Red DigiKey 5000K 5V_RTN 1 Test Point, Black DigiKey 5001K SW, PGOOD 2 Test Point, White DigiKey 5002K PCB 1 PCB, TINYBUCK_2A 5 No Load 0603 C13 1 No Load 7343 C19 1 4.7f, 25V, 20%, X5R, 1206 C17 1 No Load 8x11 Q1 1 No Load SOT23 C, N, CLKIN, CLKOUT 4 No Load Test Point C18 R8,R11, R14, R15, R16, R17 (c) 2008 Fairchild Semiconductor Corporation 7 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com 7. Assembly Diagram Figure 3. Assembly Diagram 8. PCB Layout Figure 4. PCB Layout (c) 2008 Fairchild Semiconductor Corporation 8 FEB207_FAN2103 * Rev. 0.2.1 www.fairchildsemi.com (c) 2008 Fairchild Semiconductor Corporation 9 FEB207_FAN2103 * Rev. 0.2.1