SP6123EB

SP6123 Evaluation Board Manual FEATURES








DC/DC Synchronous Buck Converter for Distributed Power Systems. Complete, Ready to Use Solutions For : Vin = 3V – 6V Vout = 0.8V – VIN (preset to 2.5V) Iout = 5.0A (no air flow required). High Efficiency: 86 to 95% Tight Line and Load Regulation Excellent Transient Response Components for Cost Effective Solution Overcurrent Protection High Switching Frequency for Small External Components. Low Power Shutdown DESCRIPTION The SP6123 Evaluation Board is designed to help users evaluate the performance of the SP6123 for using in distributed power systems. The SP6123 demo board operates over a wide input voltage range of 3V to 6V, and can deliver efficiencies over 90%. The SP6123 Evaluation Board is a complete power supply ready for use in applications where high stability, excellent transient response, high efficiency, power density and cost are critical concerns. The Evaluation Board is a completely assembled and tested PCB with surface mount components and can be used in many distributed power systems. BOARD SCHEMATIC AND LAYOUT Top Layer Bottom Layer Silkscreen Top Soldermask Top The SP6123 Eval Board is made of 2 oz copper dual layer PCB to provide improved noise immunity and minimize power losses. Components are placed on the topside of the PCB as shown. The ground pin of the IC together with all control grounds is brought to the ground of the output capacitor by the separate trace on the bottom layer and surrounded by the ground plane. The Vcc bypass capacitor CB is placed right near the Vcc pin. The traces connecting the feedback resistors are minimized. GH/GL traces are very close to the gates of the MOSFETs. The trace width of the loop connecting the inductor, output capacitors and MOSFETs is maximized. 2 2.9V to 6V CBST MBR0530 1uF R1 5 2 CB 3 2.2uF 4 GL BST VCC GH GND SWN COMP VFB 470uF D2 D2 G1 D1 G2 D1 S1 S2 8 2 7 4 6 1 5 FDS6890A SP6123 CP CIN Q1,Q2 6 U1 1 D1 5 8 7 L1 1.5uH 2.5V/4A 3 D2 R2 170K STPS2L25U RZ 15K 56pF COUT1 COUT2 COUT3 470uF 470uF 1uF R3 80K CZ1 4.7nF SP6123 Demo Board Schematic. PROGRAM THE OUTPUT VOLTAGE The resistor divider formed by R2 and R3 sets the output voltage. The output voltage is calculated using the following: R  VOUT =  2 + 1VREF ,  R3  where VREF = 0.8V. For the SP6123 demo board where VOUT = 2.5V. Choosing R3 equal to 80KΩ, then R 2 = 170 K Ω The considerations, tradeoffs and calculations required to select the power MOSFETs (Q1, Q2), the inductor (L1), the input and output capacitors Cin, Cout1 and Cout2 are discussed in detail in the SP6123 data sheet. USING THE DEMO BOARD To power the Demo Board, connect the input voltage to the VIN and GND connectors located at the bottom of the board. The input voltage range is between 3V and 6V. Connect the load between Vout and GND connectors located at the right side of the board. The output voltage is preset to 2.5V. Measure the output ripple and voltage across the output capacitors with minimum ground lead. Connecting the COMP pin to the GND can disable this power supply. 3 DEMO BOARD CHARACTERISTICS (using SP6123ACN) Vo (V) SP6123 Eval Board Line Regulation Io=2A 2.51 2.508 2.506 2.504 2.502 2.5 2.498 2.496 2.494 2.492 2.49 3 3.5 4 4.5 5 5.5 Vin (V) Vo (V) SP6123 Eval Board Load Regulation Vin=5V 2.510 2.508 2.506 2.504 2.502 2.500 2.498 2.496 2.494 2.492 2.490 0 1 2 3 4 5 Load Current (A) SP6123 Eval Board Load Regulation Vin=3.3V 2.506 2.504 2.502 Vo (V) 2.5 2.498 2.496 2.494 2.492 2.49 0 1 2 3 Load Current (A) 4 4 5 SP6123 Eval Board Efficiency Vin=5V 0.9 0.89 Efficiency 0.88 0.87 0.86 0.85 0.84 0.83 0.82 0.81 0 1 2 3 4 5 Load Current (A) SP6123 Eval Board Efficiency Vin=3.3V 0.91 Efficiency 0.9 0.89 0.88 0.87 0.86 0.85 0 1 2 3 4 5 Load Current (A) Current Limit Vs. Input Voltage 9 Overcurrent Limit (A) 8 7 6 5 4 3 2 1 0 3 3.5 4 4.5 Input Voltage (V) 5 5 5.5 Output Ripple Voltage Vin=5V, Io=2A Vin=5V, Io=4A 6 Vin=3.3V, Io=4A Vin=3.3V, Io=2A 7 Startup Waveform Ch1: Vo, Ch2: Vin. Io=2A 8 BILL OF MATERIALS Item Quantity Reference Part description Manufacturer Manufacturer P/N/ PACKAGE _______________________________________________________________________________________________________________ 1 1 CB Capacitor Ceramic 2.2uF/10V/X5R/10% TDK Corporation C2012X5R1A225K 0805 2 1 CP Capacitor Ceramic 56pF/50V/COG/5% TDK Corporation C1608COG1H560J 0603 3 4 1 2 CZ1 CBST,COUT3 Capacitor Ceramic 4.7nF/50V/X7R/10% Capacitor Ceramic 1uF/10V/X5R/10% TDK Corporation TDK Corporation C1608X7R1H472K 0603 C1608X5R1A105K 0603 5 1 CIN POSCAP 470uF/6.3V/20% SANYO 6TPB470M 6 2 COUT1,COUT2 POSCAP 470uF/4V/20% SANYO 4TPB470M 7 1 D1 Diode Schottky 30V/0.5A VISHAY MBR0530 8 1 D2 Diode Schottky 25V/2.0A ST Microelectronics STPS2L25U 9 10 1 1 L1 Q1,Q2(dual) Inductor 1.5uH/0.01Ohm DCR MOSFET 18mOhm/7.5A Coil Craft Fairchild DO3316P-152 FDS6890A SO-8 11 1 R2 Resistor 170K/63mW/1% AVX Corporation CR10--1703F-H/ 12 1 R3 Resistor 80K/63mW/1% AVX Corporation CR10--803F-H/ 13 1 RZ Resistor 15K/63mW/5% AVX Corporation CR10-153J-H/ 14 1 R1 Resistor 5 Ohm/63mW/5% AVX Corporation CR21-050J-H/ 0603 15 1 U1 SYNCH. BUCK CONTROLLER SIPEX Corporation SP6123ACN 9 SOD-123 0603 0603 0603 /SOIC-8