EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter Introduction The AAT1217 is a 1.2MHz constant frequency, current mode PWM step-up converter. It can supply a 3.3V output voltage at 100mA from a single AA cell. The device integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. A switching frequency of 1.2MHz allows the use of small, low profile inductors and ceramic capacitors. This demo board is designed for evaluating the AAT1217. The device can supply 400mA to a 3.3V load from a two AA cell input. Every demo board circuit is fully tested and supported with test data before shipping. Two versions of the evaluation board are introduced in this manual. The Rev. 1A is a more “complete” board with jumpers to select output voltage, bypass load disconnect circuitry, shutdown pin status, and the possibility to use a current probe to capture the inductor current waveform. The Rev. 2B evaluation board demonstrates a simplified circuit with only the essential external parts in the smallest possible solution size. This simplified board helps the user to evaluate the AAT1217’s performance for minimal footprint applications. Board Picture Rev. 1A Rev. 2B Figure 1: Picture of AAT1217 Rev. 1A and Rev. 2B Evaluation Boards. Parameter Input Voltage Output Voltage Accuracy Output Voltage Range Output Current Test Conditions Min Minimum Start-Up Input Voltage VIN = 1.2V, VOUT = 3.3V VIN = 2.4V, VOUT = 3.3V Typ Max Units 0.85 ±3 1 V % V 2.5 0 0 5.5 100 400 mA Table 1: AAT1217 Evaluation Board Specifications. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012 1 EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter L1 4.7µH D1 MBR0520 JP2 JP4 1 SW 6 VIN CIN 4.7µF VIN 5 VOUT AAT1217 4 3 FB SHDN Q1 Si 2305DS R4 510k VOUT R1 1. 02M C OUT 4.7µF JP1 GND 2 R2A:1002k B: 696 k C: 604 k D: 324 k Q2 2N 3904 R3 510k ON / OFF Control (JP3) 2.5V 3.0V 3.3V 5.0V Figure 2: AAT1217 Evaluation Board Rev. 1A Schematic. L1 4.7µH C3 100pF (Opt ) VIN CIN 4.7µF D1 MBR0520 1 SW 6 VIN VOUT 5 AAT1217 4 FB SHDN GND 3 VOUT R1 1. 02M C OUT 4.7µF R2 2 R2A:1002k B:696k C:604k D:324k 2.5V 3.0V 3.3V 5.0V ON / OFF Control (JP3) Figure 3: AAT1217 Evaluation Board Rev. 2B Schematic. PCB Layout The AAT1217 typically operates at 1.2MHz. This is a significantly high frequency for DC-DC converters. For satisfactory performance, PCB layout is important with high operational frequencies. The PCB traces should be as wide and as short as possible. The inductor, input capacitor, and output capacitor should be as close as possible to the AAT1217. The feedback and shutdown pin PCB traces should avoid proximity to large AC signals, such as the power inductor and switching nodes. The optional rectifier diode (D1 in Figure 4 and Figure 7) can improve efficiency and alleviate the stress 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012 EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter on the integrated power MOSFET. The diode should also be close to the inductor and the chip to form the shortest possible switching loop. While a two layer PCB layout is adequate for most applications, large multi-layer ground planes are ideal for high power applications. A large area of copper has lower resistance and would help dissipate heat from the AAT1217. The two demo boards described in this manual are four layer PCBs with two internal ground layers. The converter’s ground should join the system ground to which it supplies power at one point only. Figure 4: AAT1217 Evaluation Board Rev. 1A PCB Top Side. Figure 5: AAT1217 Evaluation Board Rev. 1A PCB Bottom Side. Figure 6: AAT1217 Evaluation Board R ev. 2B PCB Top Side. Figure 7: AAT1217 Evaluation Board Rev. 2B PCB Bottom Side. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012 3 EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter Evaluation Setup (see Figures 4, 6, and 8) Jumper Setting JP1 JP2 JP3 Description Output voltage selector. R2A:2.5V, R2B:3V, R2C:3.3V, R2D:5V (Rev.1A only) Connection between inductor and SW pin, Inductor current can be probed here (Rev.1A Only) Run/Shutdown selector Connection between VOUT pin and board output. Q1 and Q2 are designed to disconnect load from the VOUT pin when the device is shut down. Shorting this jumper will bypass this circuit and connect the VOUT pin to board output directly. (Rev.1A only) JP4 Operating the Evaluation Board Apply a DC power supply and DC voltmeter across the input voltage terminals. Set the voltage at least 0.5V below the output voltage, otherwise the board may not be able to work properly. Connect a dummy load between VOUT and GND. The board can operate with both electronic and resistor loads. When the load current is too high, the device may begin to limit the inductor current, and thus the output voltage may drop. Since the body diode of the integrated P-channel synchronous rectifier MOSFET exists from the SW pin to the VOUT pin, when VOUT < VIN, current can flow from VIN to VOUT. This happens when the device is shut down. On the Rev.1A board, a simple circuit has been added to isolate the load from VIN; during shutdown, the Q2 collector pin is pulled low to ground, or logic low, which will shut down Q1. In normal operation, the base pin of Q2 is logic high, thus the gate of Q2 is low and Q1 is conducting. The user can bypass this function by connecting JP4. Load and Line Regulation 1. Before beginning operation, set JP1 to the VOUT voltage position (R2A = 2.5V, R2B = 3.0V, R2C = 3.3V and R2D = 5.0V) and set JP3 from SHDN to RUN. 2. Vary the load and the input voltage while monitoring the output voltage. 3. The output voltage as measured at the output terminals of the evaluation boards should not vary by more than ±3% of the nominal voltage. +A+ + - - + V + V - A + Load - Figure 8: AAT1217 Connection Diagram. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012 EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter Component Part Number Description U1 L1 CIN, COUT D1 Q1 Q2 R1, R2A, R3 R2B R2C R2D R4, R5 AAT1217 CDRH5D16NP-4R7NC GRM42-6X7R475K16PT MBR0520LT1 Si2305DS (optional) 2N3904 ERJ3EKF1004V ERJ3EKF6983V ERJ3EKF6043V ERJ3EKF3243V ERJ3EKF5103V Manufacturer 1.2 MHz, 600mA Micropower Synchronous Step-Up Converter Inductor 4.7µH 2.15A Ceramic Cap 4.7µF16V X7R 1206 Schottky Diode 0.5A 20V P-Channel 1.25-W, 1.8-V (G-S) MOSFET NPN General Purpose Amplifier Res 1MΩ 1/16W 1% 0603 Res 698kΩ 1/16W 1% 0603 Res 604KΩ 1/16W 1% 0603 Res 324KΩ 1/16W 1% 0603 Res 510KΩ 1/16W 1% 0603 Skyworks Sumida Murata Onsemi Vishay Fairchild Panasonic Panasonic Panasonic Panasonic Panasonic Table 2: AAT1217 Evaluation Board Rev. 1A Bill of Materials. Component Part Number Description C3 C5 CIN COUT D1 L1 R1 R2 R3 GRM1885C1H101JA01 LLL185R71A104MA01 GRM219R61A475KE19 GRM219R61A475KE19 MBR0520LT1 CDRH2D09-4R7NC ERJ3EKF1004V ERJ3EKF6043V ERJ3EKF1004V U1 AAT1217 Ceramic Cap 100pF 50V C0G 0603 Ceramic Cap 100nF 10V X7R 0603 Ceramic Cap 4.7μF 10V X5R 0805 Ceramic Cap 4.7μF 10V X5R 0805 Schottky Diode 0.5A 20V 4.7µH Res 1MΩ 1/16W 1% 0603 Res 604kΩ 1/16W 1% 0603 Res 1MΩ 1/16W 1% 0603 1.2MHz, 600mA Micropower Synchronous Step-Up Converter Manufacturer Murata Murata Murata Murata Onsemi Sumida Panasonic Panasonic Panasonic Skyworks Table 3: AAT1217 Evaluation Board Rev. 2B Bill of Materials. Output Voltage Setting The reference voltage of AAT1217 is 1.23V. The user can change R1 and R2 to obtain needed output voltage by this formula: VOUT = R1 + R2 · 1.23V R2 The maximum VOUT is 5.5V. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012 5 EVALUATION BOARD DATA SHEET EV143 Evaluation Board for the AAT1217 600mA, 1.2 MHz Micropower Synchronous Step-Up Converter Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. 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Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202282A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 22, 2012