MIC261201 Evaluation Board 28V, 12A Hyper Speed Control Synchronous DC/DC Buck Regulator SuperSwitcher II General Description Getting Started The MIC261201 DC-DC regulator operates over an input 1. Connect an external supply to the V terminal. IN supply range of 4.5V to 28V, and provides a regulated Apply the desired input voltage to the V and ground IN output at up to 12A of output current. The output voltage is terminals of the evaluation board, paying careful adjustable to 0.8V, with a typical accuracy of 1% the attention to polarity and supply voltage. An ammeter device operates at a switching frequency of 600kHz. The may be placed between the input supply and the V IN switching frequency remains fairly constant, with changes terminal to the evaluation board. Make sure that the in input voltage and output load. supply voltage is monitored at the V terminal. The IN ammeter and/or power lead resistance can reduce the Micrels Hyper Speed Control architecture allows for voltage supplied to the input. ultra-fast transient response, while reducing the output capacitance and it also makes (High V )/ (Low V ) 2. Connect the load to the V and ground terminals. IN OUT OUT operation possible. The MIC261201 utilizes an adaptive The load can be either passive (resistive) or active (as T ripple control architecture. An undervoltage lockout in an electronic load). An ammeter can be placed ON feature is provided to ensure proper operation under between the load and the V terminal. Ensure that OUT power-sag conditions. It also includes an internal soft-start the output voltage is monitored at the V terminal. OUT feature to reduce the inrush current. Foldback current limit V can be set to 0.9V, 1.0V, 1.2V, 1.5V, 1.8V, 2.5V, OUT and hiccup mode short-circuit protection, as well as 3.3V, or 5.0V by a jumper. If a different voltage is thermal shutdown ensures protection of the IC during fault needed, adjust it by changing the feedback resistors. conditions. See Output Voltage section. Note: This evaluation board is for 12A applications. 3. Enable the MIC261201. The EN pin is provided on the evaluation board. The output of the MIC261201 turns The datasheet and other supporting documentation can be on when V exceeds the UVLO threshold. Turn off he DD found on Micrels web site at: www.micrel.com. output of the MIC261201 by shorting the EN pin to Requirements ground. A connection on the board provides easy access to the enable pin. The MIC261201 provides a 5V regulated output for input voltage V ranging from 5.5V to 28V. When V < 5.5V, IN IN V should be tied to PVIN pins to bypass the internal DD Ordering Information linear regulator by a jumper. The output load can either be active or passive. Part Number Description 12 A HSC DC-DC Regulator Evaluation Precautions MIC261201YJL EV Board The evaluation board does not have reverse polarity . protection. Applying a negative voltage to the VIN terminal may damage the device. In addition, the maximum V IN operating voltage of the MIC261201 evaluation board is 28V. Exceeding 29V on V could damage the device. IN Hyper Speed Control is a trademark 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. MIC261201 12A Evaluation Board and replacing them with the values that yield the desired Output Voltage output voltage. Once R4 is selected, R7 can be The output voltage on the MIC261201 evaluation board calculated using: is adjustable. Set it by adjusting the feedback resistors R4 V (R4 and one of R5, R6, R7, R8, R9, R10, R11, or R12) REF R7 = and can be calculated as follows as an example: V V OUT REF For V = 0.8V: REF R4 V = V (1 + ) OUT REF R7 R4 0.8V R7 = V 0.8V OUT where V = 0.8V. REF The output voltage should not be set to exceed 5V due The output voltage above is set at the factory for 1.2V to the 6.3V rating of the output capacitor and on-line output, but it can easily be changed by moving the regulation limitation. Please refer to the Setting Output jumper to a respective position to get an indicated Voltage section in the MIC261201 datasheet for more voltage on the board. If a desired voltage is not shown information. on the board, modify it by removing R4 and R7 July 2011 2 M9999-071511-A