MIC2544AYM EVALUATION BOARD Programmable Current Limit High-Side Switch General Description The MIC2544A high-side power switch is optimized for low loss DC power switching, and is ideal for Advanced Configuration and Power Interface (ACPI) and USB compliant devices. The MIC2544A features a resistor programmable output current limit and a soft start that minimizes inrush current when the switch is enabled. Thermal shutdown and current limit protect the device and the load during overload conditions. The open-drain flag output pulls low to indicate current limiting or thermal shutdown. The device features an enable input that is compatible with both 3V and 5V logic. The MIC2544A is available with active high or active low enable. This EV board is shipped with a MIC2544A-1YM installed, which features active high enable. For active low enable replace the MIC2544A-1YM with a MIC2544A-2YM; request samples at www.micrel.com. Datasheets and support documents are available on the Micrel website: www.micrel.com. Requirements This evaluation board requires a single 8.25W (minimum) bench power source adjustable from 2.7V to 5.5V, and a load. Use either an active (electronic) or passive (resistor) load. Assure that the load is rated for at least 1.5A, 8.25W. Use volt meters to measure the input and output voltages. Use an oscilloscope to view the circuit waveforms, if desired. Precautions There is no reverse input protection on this evaluation board. Be cautious when connecting the input source to ensure correct polarity is observed. Getting Started 1. VIN Supply Connect the VIN supply (typically 5V) across the VIN and GND terminals of the evaluation board. Monitor VIN at the VIN and GND terminals with a voltmeter. Do not apply power until step 5. 2. Enable Input The enable input EN is pulled up to VIN with 10kΩ resistor R4; the MIC2544A is fully enabled when power is applied to VIN. Jumper J2 is provided for hard disable. Alternatively, disable the outputs with an analog voltage applied to EN. VEN < 0.8V turns off the outputs. VEN > 2.4V turns on the outputs. 3. Output Load Connect the load across the VOUT and GND terminals. When using an electronic load, initially set it to 0A to verify that the output voltage comes up as expected before loading. The EV circuit is designed to source 1.5A at the output. 4. Monitor Outputs Monitor VOUT with a voltmeter or an oscilloscope connected across the VOUT and GND terminals. 5. Turn On the Power Turn on the VIN supply and verify that the output voltage comes up as expected. Ordering Information Part Number MIC2544AYM EV Description Evaluation board for the MIC2544A Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com May 2011 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Table 1. Current Limit vs. R1 Value Features For convenience there are a number of un-stuffed component footprints strategically placed to allow easy modification of the standard circuit. These positions are labeled NF on the schematic. The Bill of Materials indicates suggested values for these positions. Fault Output (FLG) Test point FLG monitors the flag output of the MIC2544A. FLG is an open drain output pulled up to VIN with 10kΩ resistor R2. FLG asserts low when the output current limit is reached, or when the MIC2544A enters thermal shutdown. Current Limit Output current limit is set by resistor R1. Table 1 presents a list of R1 values and their associated nominal current limits and limit ranges. For further details about selecting a value for R1 see the MIC2544A product datasheet. May 2011 2 I_OUT R1 I_OUT_Min I_OUT_Max 0.2 1150 0.140 0.260 0.3 767 0.210 0.390 0.4 575 0.280 0.520 0.5 460 0.350 0.650 0.6 383 0.480 0.720 0.7 329 0.560 0.840 0.8 288 0.640 0.960 0.9 256 0.720 1.080 1 230 0.800 1.200 1.1 209 0.880 1.320 1.2 192 0.960 1.440 1.3 177 1.040 1.560 1.4 164 1.120 1.680 1.5 153 1.200 1.800 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Typical Characteristics RDS(ON) vs. Temperature 100 RSET (Ω) vs. Output Current 2500 90 5V 140 80 70 3.3V 60 50 40 1500 RSET = 230 ILIMIT 1000 30 20 500 VIN - VOUT (mV) 2000 RSET (Ω) RDS(ON) (mΩ) VIN - VOUT vs. Output Current 160 V IN = 5V 120 85 100 25 80 60 -40 40 20 10 0 0 -40 -15 10 35 60 TEMPERATURE (°C) May 2011 85 0 0 0.25 0.5 0.75 1 1.25 1.5 OUTPUT CURRENT (A) 3 0 0.25 0.5 0.75 1 1.25 1.5 OUTPUT CURRENT (A) M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Functional Characteristics May 2011 4 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Functional Characteristics (Continued) May 2011 5 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Evaluation Board Schematic Bill of Materials Item C1 C2 C3 C4 (open) C5 (open) C6 (open) J7, J8, J9 R1 R2 R3 R4 R5 (open) R6 (open) U1 805 802 2917 805 603 603 603 603 603 603 603 603 8-SOIC Part Number Manufacturer GRM21BR60J106ME19 GRM21BR60J106ME19 TAJD227M006RNJ C2012X5R0J226M 6R3X14W104MV4T C1608X5R0J105M 5000 ERJ-3EKF1540V ERJ-3GEYJ103V ERJ-3GEY0R00V ERJ-3GEYJ103V ERJ-3GEYJ103V ERJ-3GEYJ101V MIC2544A-1YM Murata Murata AVX TDK Johanson TDK Keystone Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic MICREL Description Qty. CAP. X5R 10uF 6.3V 20% 0805 CAP. X5R 10uF 6.3V 20% 0805 CAP. Tant. 120uF 6.3V 20% 2917 CAP. X5R 22uF 6.3V 20% 0805 CAP. X7R 0.1uF 6.3V 20% 0603 CAP. X5R 1.0uF 6.3V 20% 0603 TESTPOINT, Clip, Red 0.075" Dia. RES. 154Ω 1% 0.1W 0603 RES. 10kΩ 1% 0.1W 0603 RES. 0Ω 1% 0.1W 0603 RES. 10kΩ 1% 0.1W 0603 RES. 10kΩ 1% 0.1W 0603 RES. 100Ω 1% 0.1W 0603 I.C., High-Side Switch, SOIC-8 1 1 1 0 0 0 3 1 1 1 1 0 0 1 Notes: 1. Murata: http://www.murata.com 2. AVX: www.avx.com 3. TDK: www.tdk.com 4. Johanson: http://www.johansontechnology.com/ 5. Keystone: http://www.keyelco.com 6. Panasonic: http://www.panasonic.com/industrial/electronic-components 7. Micrel, Inc.: www.micrel.com May 2011 6 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Evaluation Board PCB Layout Top Layer Silkscreen Top Layer Traces May 2011 7 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Evaluation Board PCB Layout (Continued) Bottom Layer Traces Bottom Layer Silkscreen May 2011 8 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board Evaluation Board PCB Layout (Continued) Board Dimensions May 2011 9 M9999-050311-B Micrel, Inc. MIC2544A Evaluation Board 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 Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. 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. May 2011 10 M9999-050311-B