MIC261203 Evaluation Board 28V, 12A HyperLight Load Synchronous DC-DC Buck Regulator TM SuperSwitcher IIG General Description Getting Started The MIC261203 DC-DC regulator operates over an input 1. Connect an external supply to the V IN supply range of 4.5V to 28V, and provides a regulated terminal. Apply the desired input voltage to the output at up to 12A of output current. The output voltage V and ground terminals of the evaluation IN is adjustable to 0.8V with a typical accuracy of 1% the board, paying careful attention to polarity and device operates at a switching frequency of 600kHz. The supply voltage. An ammeter may be placed switching frequency remains fairly constant with changes between the input supply and the V terminal to IN in input voltage and output load. the evaluation board. Ensure that the supply Micrels Hyper Light Load architecture provides the voltage is monitored at the V terminal. The IN same high-efficiency and ultra-fast transient response as ammeter and/or power lead resistance can the Hyper Speed Control architecture under medium reduce the voltage supplied to the input. to heavy loads, but also maintains high efficiency under 2. Connect the load to the V and ground OUT light load conditions by transitioning to variable terminals. The load can be either passive frequency, discontinuous mode operation. (resistive) or active (as in an electronic load). The MIC261203 utilizes an adaptive T ripple control ON An ammeter can be placed between the load architecture. An undervoltage lockout feature is provided and the V terminal. Ensure that the output OUT to ensure proper operation under power-sag conditions. voltage is monitored at the V terminal. V OUT OUT An internal soft-start feature is provided to reduce the can be set to 0.9V, 1.0V, 1.2V, 1.5V, 1.8V, inrush current. Foldback current limit and hiccup mode 2.5V, 3.3V, or 5.0V by a jumper. If a different short-circuit protection and thermal shutdown ensures voltage is needed, it can be adjusted by protection of the IC during fault conditions. changing the feedback resistors. See Output Note: This evaluation board is for 12A applications. Voltage section. The datasheet and supporting documentation can be 3. Enable the MIC261203. The EN pin is provided found on Micrels web site at: www.micrel.com. on the evaluation board. The output of the Requirements exceeds the MIC261203 turns on when V DD UVLO threshold. The output of the MIC261203 The MIC261203 provides a 5V regulated output for input may be turned off by shorting the EN pin to voltage V ranging from 5.5V to 28V. When V < 5.5V, IN IN ground. A connection on the board provides V should be tied to PVIN pins to bypass the internal DD easy access to the enable pin. linear regulator by a jumper. The output load can either be active or passive. Precautions Ordering Information The evaluation board does not have reverse polarity Part Number Description protection. Applying a negative voltage to the VIN 12A HLL DC-DC Regulator terminal may damage the device. In addition, the MIC261203YJL EV Evaluation Board maximum V operating voltage of the MIC261203 IN evaluation board is 28V. Exceeding 29V on V could IN damage the device. Hyper Light Load and Hyper Speed Control are trademarks of Micrel, Inc. MLF and MicroLead Frame are registered trademarks of Amkor Technology, Inc. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC261203 10A Evaluation Board them with the values that yield the desired output voltage. Output Voltage Once R4 is selected, R7 can be calculated using: The output voltage on the MIC261203 evaluation board is R4 V adjustable. It is set by adjusting the feedback resistors (R4 REF R7 = and one of R5, R6, R7, R8, R9, R10, R11, or R12) and V V OUT REF can be calculated as follows as an example: R4 V = V (1 + ) For V = 0.8V: OUT REF REF R7 R4 0.8V R7 = V 0.8V where V = 0.8V. REF OUT The output voltage above is set at the factory for a 1.2V The output voltage should not be set to exceed 5V due to output, but it can easily be changed by moving the jumper the 6.3V rating of the output capacitor and online to a respective position to get an indicated voltage on the regulation limitations. Please refer to the Setting Output board. If a desired voltage is not shown on the board, it is Voltage section in the MIC261203 datasheet for more easily modified by removing R4 and R7 and replacing information. July 2011 2 M9999-071511-A