MIC2295 MLF® Evaluation Board 1.2MHz PWM Step-Up Converter General Description The Micrel MIC2295 is a small 1.2MHz constant frequency PWM DC/DC step-up switching regulator. The MIC2295 is available in either a thin SOT-23 or a 2mm x 2mm MLF® package. High power densities, in a very small size, are achieved using its internal 34V/1.2A switch. Requirements The MIC2295 evaluation board requires an input power source that is able to deliver greater than 1.2A at 2.5V. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN terminal may damage the device. The MIC2295 evaluation board is tailored for a Li-ion range input supply voltage. The MIC2295 evaluation board should not exceed 6.3V on the input unless the standard input capacitor is replaced with a higher rated input capacitor. Getting Started 1. Connect an external supply to VIN. Apply desired input voltage to the VIN (J1) and ground (J2 and J5) terminals of the evaluation board, paying careful attention to polarity and supply voltage (2.5V≤VIN≤6.3V). An ammeter may be placed between the input supply and the VIN terminal to the evaluation board. Ensure that the supply voltage is monitored at the VIN terminal. The ammeter and/or power lead resistance can reduce the voltage supplied to the input. A 10uF input capacitor is used on the evaluation board to help compensate for long cables used in most lab settings. 2. Connect the load to the VOUT (J4) and ground terminals. The load can be either passive (resistor) or active (electronic load). An ammeter can be placed between the load and the VOUT terminal. The default output voltage is set to 12V. This can be adjusted by changing the feedback resistors. 3. Enabling the MIC2295. Apply a 1.5V or greater voltage to the enable (J3) terminal. Ordering Information Part Number Description MIC2295YML EV 1.2MHz PWM Step-Up Converter MLF is a registered trademark of Amkor Technology, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com February 2009 M9999-020509-B Micrel, Inc. MIC2295 Evaluation Board VOUT Output Voltage The output voltage on the MIC2295 evaluation board is adjustable. The output voltage is controlled by the feedback resistors (R1 and R2) and can be calculated as follows: R1 + 1) VOUT = 1.24V ( R2 1.24V Ensure the output voltage selected does not exceed the 25V rating of the output capacitor. When output voltages greater than 25V are desired, the output capacitor should be replaced with one rated greater than the maximum output voltage. The following chart defines the minimum output capacitor value recommended for different output voltages. The evaluation board is initially adjusted to 12V, but can easily be modified by removing R1 and replacing it with the value that yields the desired output voltage. (Caution: Do not power up the MIC2295 SOT-23 version with R1 removed. The SOT-23 version does not have over-voltage protection thus the output voltage will steadily increase until the device selfdestructs). Output Voltage <6V <16V <34V Recommended Output Capacitor 22uF 10uF 4.7uF MIC2295 Schematic February 2009 2 M9999-020509-B (408) 955-1690 Micrel, Inc. MIC2295 Evaluation Board Bill of Materials Item C1 Part Number 08056D106MAT C1608X5R0J106K GRM21BR61A106KE19L C2 1206YD475MAT C3216X5R1C475K GRM31CR61C475KA12L D1 MBRX140 1N5819HW L1 LQH43CN100K03 VLF4012AT-100MR79 R1 R2 R3 U1 CRCW06034322FRT1 CRCW06034991FRT1 CRCW06031002FRT1 MIC2295YML Manufacturer Description Qty. (1) 10µF 6.3V 0805 X5R Ceramic Capacitor 1 (2) 10µF 6.3V 0603 X5R Ceramic Capacitor 1 10µF 6.3V 0805 X5R Ceramic Capacitor 1 4.7µF 25V 1206 X5R Ceramic Capacitor 1 AVX TDK Murata (3) (1) AVX (2) TDK Murata MCC 1 (3) 1 (4) Diodes Inc Murata 1A 40V Schottky Diode (6) (3) (2) 1 1 10µH 650mA Inductor 1 10µH 800mA Inductor 1 (6) 43.2kΩ 0603 Resistor 1 (6) 4.99kΩ 0603 Resistor 1 10kΩ 0603 Resistor 1 1.2MHz PWM Step-Up Converter 1 TDK Vishay Vishay (6) Vishay Micrel, Inc. (7) Notes: 1. AVX: www.avx.com. 2. TDK: www.tdk.com. 3. Murata: www.murata.com. 4. Micro Commercial Components (MCC): www.mccsemi.com. 5. Diodes Inc: www.diodes.com. 6. Vishay: www.vishay.com. 7. Micrel, Inc.: www.micrel.com. February 2009 3 M9999-020509-B (408) 955-1690 Micrel, Inc. MIC2295 Evaluation Board Printed Circuit Board Layouts 2mm x 2mm MLF® (YML) Evaluation Board Figure 1a. Top Silkscreen Figure 1b. Top Layer Figure 1c. Bottom Silkscreen Figure 1d. Bottom Layer MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel Incorporated February 2009 4 M9999-020509-B (408) 955-1690