MIC4950 Evaluation Board HyperSpeed™ 5A Buck Regulator in 3mm x 4mm DFN Package Revision 1.0 General Description This board enables the evaluation of the MIC4950, a fully integrated 5A switching regulator featuring HyperSpeed™ control and Power Good output indication. The MIC4950 is highly efficient throughout the entire output current range, exceeding 95% at5V input to 3.3V output. The tiny 3mm x 4mm DFN package, in combination with the high switching frequency, allows for a compact, small footprint solution. The MIC4950 provides accurate output voltage regulation under the most demanding conditions and responds extremely fast to a load transient with exceptionally small output voltage ripple. Data sheets and other support documents can be found on Micrel’s web site at: www.micrel.com. Requirements The MIC4950 evaluation board requires a single power source adjustable up to at least 5.5V, with 5A of current capability. The load can either be active (electronic load) or passive (resistor) with the capability to dissipate 20W. It is ideal to have an oscilloscope available to view the circuit waveforms, but not essential. For the simplest tests, two Voltage meters are required to measure input and output voltage. For efficiency measurements, two voltage meters and two ammeters are required to prevent errors due to measurement inaccuracies. Precautions There is no reverse input protection on this board. Be certain that the correct polarity is observed when connecting the input source. The maximum VIN of the board is rated at 5.5V, and the maximum load current is rated at 5A. Input power leads should ensure negligible voltage drop up to the maximum load, and should be kept as short as possible to minimize inductance. For load transient, and/or pre-biased output start-up testing up to 5.5V VIN, the use of a bulk electrolytic capacitor in position C7 (at least 100µF, 10V rating) is recommended. Getting Started 1. Connect an external supply to the VIN (J1) terminal and GND (J2). With the output of the power supply disabled, set its voltage to the desired input test voltage (2.7V ≤ VIN ≤ 5.5V). An ammeter may be placed between the input supply and the VIN (TP4) terminal. Be sure to monitor the supply voltage at the VIN (TP4) terminal, as the ammeter and/or power lead resistance can reduce the voltage supplied to the device. 2. Connect a load to the VOUT (J3) and ground (J4) terminals. The load can be either active passive (resistive) or active (electronic load). In case of electronic load, keep the load disabled until the MIC4950 has been powered up. An ammeter may be placed between the load and the output terminal. Ensure the output voltage is monitored at the VOUT (TP6) terminal. 3. Enable the MIC4950. The MIC4950 evaluation board has a pull-up resistor R6 to VIN. With a jumper installed in positions 1-2 of TP5, the output voltage will be enabled when the input supply of >2.7V is applied. To disable the device, apply a voltage below 0.5V to the EN (TP2) terminal, or install a jumper across positions 2-3 of TP5. 4. Power Good. A Power good test point (TP3) is provided to monitor the Power Good function. The Power Good output will go high approximately 80µs after the output voltage reaches 88% of its nominal voltage. Ordering Information Part Number Description MIC4950YFL EV 1.8V Fixed Output Evaluation Board Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. HyperSpeed is a trademark of Micrel, 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 April 15, 2014 041514-1.0 Micrel, Inc. MIC4950 Evaluation Board Other Features Evaluation Board Feedback Resistors (R1, R2) for Adjustable Output The output voltage is set nominally to 1.8V. This output can be changed by adjusting the upper resistor, R1, in the feedback potential divider. Therefore: R2 = R1 x VREF/(VOUT-VREF) Where VREF = 0.625V Some example values are: VOUT R1 R2 1.0V 120k 180k 1.2V 274k 294k 1.5V 316k 226k 1.8V 301k 160k 2.5V 316k 105k 3.3V 309k 71.5k The feed-forward capacitor, C3, is typically in the range 22pF-39pF. The MIC4950 features an internal ripple injection network, whose current is injected into the FB node and integrated by C3, thus the waveform at FB is approximately a triangular ripple. The size of C3 dictates the amount of ripple amplitude at the FB node. Smaller values of C3 yield higher FB ripple amplitude and better stability, but also degrade somewhat line regulation and transient response. April 15, 2014 2 041514-1.0 Micrel, Inc. MIC4950 Evaluation Board Evaluation Board Schematic Bill of Materials Item Part Number C1, C2 C2012X5R1A106M125AB C3 C4 GRM219R61A106ME44 C1608C0G1H220J080AA GRM1885C1H220JA01 C1608X5R1A105M080AC GRM185R61A105ME26 Manufacturer TDK(1) Murata(2) TDK Murata TDK Murata Description Qty. Ceramic Capacitor, 10µF, 10V, X5R, Size 0805 2 Ceramic Capacitor, 22pF, 50V, C0G, Size 0603 1 Ceramic Capacitor, 1µF, 10V, X5R, Size 0603 1 C5 - - Not Fitted (FT), Size 0603 0 C6 - - Not Fitted (FT), Size 1210 0 C7 - - Not Fitted (FT), Radial, 8mm diameter polarized capacitor 0 RLF7030T-1R0N6R4 TDK 1µH, 6.4A, 7.3mΩ, L7.3mm x W6.8mm x H3.2mm CLF7045T-1R0N TDK 1µH, 5.2A, 9.6mΩ, L7.2mm x W6.9mm x H4.5mm CDRH8D43RT125NP-1R0NC Sumida(3) 1µH, 7.5A, 7.8mΩ, L8.5mm x W8.3mm x H4.5 mm R1 CRCW06033013FK Vishay(4) Resistor, 301kΩ, Size 0603 1 R2 CRCW06031603F Vishay Resistor, 160kΩ, Size 0603 1 R3 - - Not Fitted (FT), Size 0603 0 R4 CRCW060310R0FK Vishay Resistor, 10Ω, Size 0603 1 R5 CRCW06031002FK Vishay Resistor, 10kΩ, Size 0603 1 R6 CRCW06031003FK Vishay Resistor, 100kΩ, Size 0603 1 R7 CRCW060349R9FK Vishay Resistor, 49.9Ω, Size 0603 1 U1 MIC4950YFL HyperSpeed™ 5A Buck Regulator 1 L1 Micrel, Inc.(5) 1 Notes: 1. TDK: www.tdk.com. 2. Murata: www.murata.com. 3. Sumida: www.sumida.com 4. Vishay: www.vishay.com. 5. Micrel, Inc.: www.micrel.com. April 15, 2014 3 041514-1.0 Micrel, Inc. MIC4950 Evaluation Board PCB Layout Recommendations Top Layer Bottom Layer April 15, 2014 4 041514-1.0 Micrel, Inc. MIC4950 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. © 2014 Micrel, Incorporated. April 15, 2014 5 041514-1.0 Micrel, Inc. MIC4950 Evaluation Board Revision History Date Change Description/Edits by: 1/12/10 Changed dates in template. M. Galvan 0.5 8/4/10 Added new paragraph to disclaimer in boiler plate. Per Colin Sturt. M.Galvan 1.0 1/7/13 Complete rework 2.0 4/30/13 Made notes run continuously, rather than restart on each page 2.1 April 15, 2014 Rev. 6 041514-1.0