MIC28304 Evaluation Board 70V 3A Power Module Hyper Speed Control Family General Description Getting Started The Micrel MIC28304 is synchronous step-down regulator 1. VIN Supply module, featuring a unique adaptive ON-time control Connect a supply to the VIN and GND terminals, architecture. The module incorporates a DC-to-DC paying careful attention to the polarity and the supply controller, power MOSFETs, bootstrap diode, bootstrap range (7V < VIN < 70V). Monitor IIN with a current capacitor, and an inductor in a single package. The meter and monitor input voltage at VIN and GND MIC28304 operates over an input supply range of 4.5V to terminals with a voltmeter. Do not apply power until 70V and can be used to supply up to 3A of output current. step 4. The output voltage is adjustable down to 0.8V with a 2. Connect Load and Monitor Output guaranteed accuracy of 1%. The device operates with a programmable switching frequency from 200kHz to Connect a load to the VOUT and GND terminals. The 600kHz. load can be either a passive (resistive) or an active (as in an electronic load) type. A current meter may be The MIC28304-1 has the HyperLight Load architecture, placed between the VOUT terminal and load to so it can operate in pulse skipping mode at light load. monitor the output current. Ensure the output voltage However, it operates in fixed frequency CCM mode from is monitored at the VOUT terminal. medium load to heavy load. The MIC28304-2 has Hyper Speed Control architecture, which operates in fixed 3. Enable Input frequency CCM mode under all load conditions. The EN pin has an on board 100k pull-up resistor (R16) to VIN, which allows the output to be turned on The basic parameters of the evaluation board are: when PVDD exceeds its UVLO threshold. An EN Input: 7V to 70V connector is provided on the evaluation board for (1) users to easily access the enable feature. Applying an Output: 0.8V to 5V at 3A external logic signal on the EN pin to pull it low or 600kHz Switching Frequency (Adjustable 200kHz using a jumper to short the EN pin to GND will shut off to 600kHz) the output of the MIC28304 evaluation board. Note: 4. Turn Power 1. Refer to temperature curves shown in the MIC28304 0.8V to 5V/3A Evaluation Board Typical Characteristics section. Turn on the VIN supply and verify that the output voltage is regulated to 5V. Datasheets and support documentation are available on Micrels web site at: www.micrel.com. Ordering Information Requirements Part Number Description The MIC28304-1 and MIC28304-2 evaluation board MIC28304-1 Evaluation requires only a single power supply with at least 10A MIC28304-1 5V EV Board up to 5V Output current capability. No external linear regulator is required to power the internal biasing of the IC because the MIC28304-2 Evaluation MIC28304-2 5V EV MIC28304 has internal PVDD LDO. In the applications Board up to 5V Output with VIN < +5.5V, PVDD should be tied to VIN to bypass MIC28304-1 Evaluation MIC28304-1 12V EV the internal linear regulator. The output load can either be Board 12V Output a passive or an active load. MIC28304-2 Evaluation MIC28304-2 12V EV Precautions Board 12V Output The MIC28304 evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN and GND terminals may damage the device. The maximum VIN of the board is rated at 70V. Exceeding 70V on the VIN could damage the device. Hyper LightLoad is a registered trademark and Hyper Speed Control 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 Micrel, Inc. MIC28304 Evaluation Board gives a 0.8V output voltage. All other voltages not listed Features above can be set by modifying R value according to: BOTTOM Feedback Resistors R1 V The output voltage on the MIC28304 evaluation board, REF Eq. 2 R = BOTTOM which is preset to 5.0V, is determined by the feedback V V OUT REF divider: Note that the output voltage should not be set to exceed R1 5V due to the 6.3V voltage rating on the output capacitors. V = V 1 + Eq. 1 OUT REF For higher output voltage, use the Ordering Information R BOTTOM table. Table 1 gives the typical values of some of the components, for details refer to Bill of Material table. where V = 0.8V, and R is one of R10, or R11, REF BOTTOM which corresponds to 3.3V, 5V. Leaving the R open BOTTOM Table 1. Typical Values of Some Components R1 R11 R3 C10 C12 V VIN (R ) (Top Feedback Resistor) (Bottom Feedback Resistor) (C ) (C ) C OUT inj inj ff OUT 47F /6.3V 0.9V 5V to 70V 16.5k 10k 80.6k 0.1F 2.2nF or 2 x 22F 47F /6.3V 1.2V 5V to 70V 16.5k 10k 20k 0.1F 2.2nF or 2 x 22F 47F /6.3V 0.1F 2.2nF 1.8V 5V to 70V 16.5k 10k 8.06k or 2 x 22F 47F /6.3V 0.1F 2.2nF 2.5V 5V to 70V 16.5k 10k 4.75k or 2 x 22F 47F /6.3V 0.1F 2.2nF 3.3V 5V to 70V 16.5k 10k 3.24k or 2 x 22F 47F/6.3V 5V 7V to 70V 16.5k 10k 1.9k 0.1F 2.2nF or 2 x 22F 47F/16V 12V 18V to 70V 23.2k 10k 715 0.1F 2.2nF or 2 x 22F Revision 1.0 April 29, 2014 2