MIC33030 Evaluation Board 8MHz Internal Inductor, 400mA Buck Regulator with HyperLight Load™ General Description This evaluation board enables the evaluation of the MIC33030, a fully-integrated 400mA, 8MHz switching regulator featuring an internal inductor and HyperLight Load™ mode. The MIC33030 is efficient throughout the entire output current range, drawing just 20μA of quiescent current in operation. The tiny 2.0mm x 2.5mm MLF® package, in combination with the internal inductor, enables a compact solution with only two external components. The MIC33030 provides accurate output voltage regulation under the most demanding conditions and responds extremely quickly to a load transient with exceptionally small output voltage ripple. Requirements This board needs a single 2W bench power source adjustable from 2.7V to 5.5V. The loads can either be active (electronic load) or passive (resistor) with the capability to dissipate 1W. 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 cautious when connecting the input source to ensure correct polarity is observed. Getting Started 1. Connect an external supply to the VIN terminal and GND. 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 terminal. Be sure to monitor the supply voltage at the VIN terminal, as the ammeter and/or power lead resistance can reduce the voltage supplied to the device. 2. Connect a load to the VOUT and GND terminals. The load can be either passive (resistive) or active (electronic load). An ammeter may be placed between the load and the output terminal. Ensure the output voltage is monitored at the VOUT terminal. 3. Enable the MIC33030. The MIC33030 evaluation board has a pull-up resistor to VIN. By default, 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 terminal or jumper the EN terminal-to-GND. Ordering Information Part Number Description MIC33030-AYHJ MIC33030 Internal Inductor Buck Regulator, Adjustable Evaluation Board MIC33030-4YHJ MIC33030 Internal Inductor Buck Regulator, VOUT=1.2V Evaluation Board HyperLight Load is a trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademark Amkor Technology 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 January 2011 M9999-011211-A Micrel, Inc. MIC33030 Evaluation Board HyperLight Load™ Mode The MIC33030 uses a minimum on and off time proprietary control loop (patented by Micrel). When the output voltage falls below the regulation threshold, the error comparator begins a switching cycle that turns the PMOS on and keeps it on for the duration of the minimum-on-time. This increases the output voltage. If the output voltage is over the regulation threshold, then the error comparator turns the PMOS off for a minimumoff-time until the output drops below the threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using a NMOS switch instead of a diode allows for lower voltage drop across the switching device when it is on. The asynchronous switching combination between the PMOS and the NMOS allows the control loop to work in discontinuous mode for light load operations. In discontinuous mode, the MIC33030 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases, thus provides more energy to the output. This switching scheme improves the efficiency of MIC33030 during light load currents by only switching when it is needed. As the load current increases, the MIC33030 goes into continuous conduction mode (CCM) and switches at a frequency centered at 8MHz. The load current at which the MIC33030 goes into continuous conduction mode may be approximated to 150mA. Evaluation Board Other Features Feedback Resistors (R2, R3) for Adjustable Output The output voltage is set nominally to 1.8V. This output can be changed by adjusting the upper resistor (R2) in the feedback potential divider. Therefore: R2 = R3*(VO-VREF)/VREF Where VREF = 0.62V Some example values are: VOUT R2 R3 1.2V 274k 294k 1.5V 316k 221k 1.8V 301k 158k 2.5V 324k 107k 3.3V 309k 71.5k The Feed-forward capacitor (C3) is typically not fitted since transient load regulation is already very good. However, it can be improved slightly by fitting a capacitor at C3 to inject fast output voltage deviations directly into the feedback comparator. This improved load regulation is at the expense of slightly increasing the amount of noise on the output at higher loads. Values between 100pF and 1nF are recommended to prevent instability. January 2011 2 M9999-011211-A Micrel, Inc. MIC33030 Evaluation Board Evaluation Board Performance 90.0% 80.0% 1000 VIN=3.6V 100 10 1 VIN=4.2V 0.1 0.01 0.001 0.1 10 LOAD CURRENT (mA) 90.0% 70.0% 1000 VIN=5V 60.0% 50.0% 40.0% 30.0% 50.0% VIN=4.2V 30.0% 20.0% 10.0% 1000 VIN=3.6V 40.0% 10.0% 0.1 10 LOAD CURRENT (mA) VIN=3V 60.0% 20.0% 0.0% 0.001 Efficiency vs Load (VOUT = 1.8V) 80.0% VIN=3.6V 70.0% EFFICIENCY (%) SWITCHING FREQUENCY (kHz) VIN=3V Efficiency vs. Load (VOUT = 2.5V) Efficiency (%) 10000 Switching Frequency vs. Load Current 0.0% 0.001 0.1 10 Load Current (mA) 1000 Enable (ON) Voltage vs. Input Voltage 1.2 ENABLE VOLTAGE (V) 1.0 TA=25°C 0.8 0.6 0.4 0.2 0.0 2.5 3.5 4.5 5.5 INPUT VOLTAGE (V) January 2011 6.5 3 M9999-011211-A Micrel, Inc. MIC33030 Evaluation Board MIC33030 Evaluation Board Schematic (Fixed Output) Bill of Materials Item C1, C2 C3 R1 Part Number CRCW06031002FKEA − R2, R3 U1 Manufacturer C1608X5R0J475K GRM188R60J475KE19D − MIC33030-xYHJ TDK(1) (2) Murata − (3) Vishay − Micrel, Inc.(4) Description Qty. Ceramic Capacitor, 4.7µF, 6.3V, X5R, Size 0603 2 Not Fitted (NF) 0 Resistor, 10k, Size 0603 1 Not Fitted (NF) 0 8MHz, 400mA Internal Inductor Buck Regulator with HyperLight Load™ 1 Notes: 1. TDK: www.tdk.com. 2. Murata: www.murata.com. 3. Vishay: www.vishay.com. 4. Micrel, Inc.: www.micrel.com. January 2011 4 M9999-011211-A Micrel, Inc. MIC33030 Evaluation Board MIC33030 Evaluation Board Schematic (Adjustable Output) VOUT = 1.8v Bill of Materials Item Part Number C1, C2 C1608X5R0J475K GRM188R60J475KE19D C3 NF R1 R2 R3 U1 CRCW06031002FKEA CRCW06031583FKEA CRCW06033013FKEA MIC33030-AYHJ Manufacturer Description Qty. (1) TDK (2) Murata − Ceramic Capacitor, 4.7µF, 6.3V, X5R, Size 0603 2 Not Fitted 0 (3) Resistor, 10k, Size 0603 1 (3) Resistor, 158k, Size 0603 1 Resistor, 301k, Size 0603 1 8MHz, 400mA Internal Inductor Buck Regulator with HyperLight Load™, with Adjustable Output Voltage 1 Vishay Vishay (3) Vishay Micrel, Inc.(4) Notes: 1. TDK: www.tdk.com. 2. Murata: www.murata.com. 3. Vishay: www.vishay.com. 4. Micrel, Inc.: www.micrel.com. January 2011 5 M9999-011211-A Micrel, Inc. MIC33030 Evaluation Board PCB Layout Recommendations MIC33030 EVB Top Layer MIC33030 EVB Bottom Layer January 2011 6 M9999-011211-A Micrel, Inc. MIC33030 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. © 2011 Micrel, Incorporated. January 2011 7 M9999-011211-A