EV-102 AAT1150 EVAL 1A Buck DC/DC Switch Mode Regulator Introduction The AAT1150 MSOP evaluation board demonstrates performance, along with the suggested size and placement of external components, for the AAT1150 integrated buck regulator. The external components are selected for minimum size and optimum operation up to 1A output current. Please refer to the AAT1150 product datasheet for more details about this product. Layout As with all switching power supplies, board layout for the AAT1150 is critical. Special care has been taken with placement of the external components. The input capacitor (C1) placement is critical and must be located immediately adjacent to the AAT1150. As shown in Figure 2, the LX node trace has been routed under C1 in order to facilitate placement of C1 close to the IC. The output voltage feedback trace has been routed on the portion of backside of the board which has a ground plane on the top side (see Figure 3). The trace is routed to avoid the LX node and associated noise. Please refer to Table 1 for AAT1150 evaluation board specifications. VIN+ AAT1150 5 R1 100 R2 3 100k C7 0.1µF C1 10µF 4 2 VP FB VCC LX EN LX GND PGND Vo+ R3 1 7 L1 4.1µH 6 8 C2-C4 3x 22µF 6.3V X5R R4 10kΩ 1% GND EN Figure 1: AAT1150 Evaluation Board Schematic. Specification Input Voltage Test Conditions Min Typ Max Units 2.7 3.6 5.5 V Output Error Voltage Output Current ±3 0 % 1.0 A Table 1: AAT1150 Evaluation Board Specifications. EV-102.2005.07.1.1 1 EV-102 AAT1150 EVAL 1A Buck DC/DC Switch Mode Regulator Figure 2: AAT1150 Evaluation Board PCB Top Side. Figure 3: AAT1150 Evaluation Board PCB Bottom Side. Test Equipment 1. 6.0V 1.0A laboratory power supply: HP33401A or equivalent. 2. DC 0A to 1.0A load capable of operation down to 1.0V: Keithley 2400 or equivalent. When using the Keithley 2400, set the meter to 0V in voltage source mode and set the load current by varying the current compliance (maximum current) of the meter. 3. DC voltmeter: HP34401A or equivalent. 4. Oscilloscope: Tektronix TDS744A or equivalent. Setup and Test A: Load and Line Regulation (see connection diagram in Figure 4) 1. Apply a DC power supply and DC voltmeter across input voltage terminals: VIN+ (positive terminal) and GND (negative terminal or return). 2. Apply a DC load and DC voltmeter to output terminals VO+ and GND. 3. Vary the load from 0A to 1.0A and the input voltage from 2.7V to 5.5V while monitoring the output voltage. 4. The output voltage as measured at the output terminals of the evaluation board should not vary by more than ±3% of the nominal voltage. B: Short-Circuit and Over-Temperature Protection 1. Raise the input voltage to 5.5V. 2. Apply a short from VO+ to GND at the evaluation board terminals. 3. Remove the short and verify that output returns to it initial value. C: Enable Input 1. Short the enable pin to GND. The output should decay to zero. 2. Remove the short applied to the enable pin. The output should recover to its initial value. 2 EV-102.2005.07.1.1 EV-102 AAT1150 EVAL 1A Buck DC/DC Switch Mode Regulator 1.500V Load Voltmeter 0-1A Power Supply 3.650V 0.147A 3.600V Voltmeter Figure 4: AAT1150 Connection Diagram. Component U1 U1 U1 U1 U1 C2, C3, C4 C1 C7 R1 R2 R3 R4 L1 Part Number Description AAT1150IKS-1.0-T1 AAT1150IKS-1.5-T1 AAT1150IKS-1.8-T1 AAT1150IKS-2.5-T1 AAT1150IKS-3.3-T1 GRM21BR60J226KE19 GRM319R60J106KE01 GRM188F51E104ZA01 Chip Resistor Chip Resistor Chip Resistor Chip Resistor 1.0V 1MHz 1A Buck Converter 1.5V 1MHz 1A Buck Converter 1.8V 1MHz 1A Buck Converter 2.5V 1MHz 1A Buck Converter 3.3V 1MHz 1A Buck Converter 22µF, 6.3V, X5R, 10%, 0805 10µF, 6.3V, X5R, 10%, 1206 0.1µF, 25V, Y5V, 10%, 0603 100kΩ, 5%, 1/10W; 0603 100kΩ, 5%, 1/10W; 0603 See Table 3; 1%, 1/16W; 0402 10kΩ, 1%, 1/16W; 0402 (required for output greater than 1.0V only) 4.1µH 57mΩ 1.95A Shielded CDRH5D18-4R1 Manufacturer AnalogicTech AnalogicTech AnalogicTech AnalogicTech AnalogicTech MuRata MuRata MuRata Vishay Vishay Vishay Vishay Sumida Table 2: AAT1150 EVAL Bill of Materials. EV-102.2005.07.1.1 3 EV-102 AAT1150 EVAL 1A Buck DC/DC Switch Mode Regulator Output Voltage For an adjustable output, set R4 to 10kΩ and select R3 according to Table 3. For fixed output versions, R4 can be omitted and R3 is a short. VO (V) Ω) R3 (kΩ 1.0 1.1 1.2 1.25 1.3 1.4 1.5 1.6 1.7 1.8 1.85 1.9 2.0 2.1 2.2 2.3 2.4 2.5 3.3 0.00 (short) 1.00 2.00 2.55 3.01 4.02 4.99 6.04 6.98 8.06 8.45 9.09 10.0 11.0 12.1 13.0 14.0 15.0 23.2 Ω). Table 3: Resistor Selection for Adjustable Output Voltage (R4 = 10kΩ AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 4 EV-102.2005.07.1.1