MIC23163YMT-EV

MIC23163/4 Evaluation Board 4MHz PWM 2A Buck Regulator with HyperLight Load® and Power Good General Description Getting Started The MIC23163/4 evaluation board allows the customer to evaluate a fully-integrated 2A, 4MHz synchronous buck ® regulator that features HyperLight Load mode, a Power Good output indicator, and programmable soft-start. The MIC23163/4 is highly efficient throughout the output current range. The tiny 2mm x 2mm DFN package, in combination with the 4MHz switching frequency, provides a compact sub-1mm height solution that requires few external components. The MIC23163/4 has a maximum 100% duty cycle and incorporates an active discharge feature. It provides accurate output voltage regulation under the most demanding conditions and responds extremely quickly to a load transient with exceptionally small output voltage ripple. 1. Connect an external supply to the VIN (J4) and GND (J3) terminals. 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 (J4) terminal. Be sure to monitor the supply voltage at the VIN (J4) terminal, as the ammeter and/or power lead resistance can reduce the voltage supplied to the device. Requirements The MIC23156 evaluation board requires a single 15W bench power source adjustable from 2.7V to 5.5V. The loads can either be active (electronic load) or passive (resistor), and must be able to dissipate 10W. It is ideal, but not essential, to have an oscilloscope available to view the circuit waveforms. The simplest tests require two voltage meters to measure input and output voltages. Efficiency measurements require two voltage meters and two ammeters to prevent errors caused by measurement inaccuracies. Precautions There is no reverse input protection on this board. Be careful when connecting the input source to ensure correct polarity is observed. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. 2. Connect a load to the VOUT (J1) and GND (J2) terminals. The load can be either passive (resistive) or active (electronic load). An ammeter may be placed between the load and the output terminal. Make sure the output voltage is monitored at the VOUT (J1) terminal. 3. Enable the MIC23163/4. The MIC23163/4 evaluation board has a pull-up resistor to VIN. By default, the output voltage is enabled when the input supply of >2.7V is applied. To disable the device, apply a voltage below 0.5V to the EN (J6) terminal. 4. Power Good. A PG test point (J5) is provided to monitor the Power Good feature. The Power Good output will go high (VOUT) approximately 90µs after the output voltage reaches 92% of its nominal voltage. Ordering Information Part Number Description MIC23163YMT EV MIC23163 Evaluation Board MIC23164YMT EV MIC23164 Evaluation Board HyperLight Load is a registered 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 August 23, 2013 Revision 1.0 Micrel, Inc. MIC23156 Evaluation Board The feedforward capacitor, C4, provides essential compensation for the MIC23163/4. A typical value range of 15pF to 68pF is recommended. Evaluation Board Power Good (PG) The evaluation board has a test point provided for testing the Power Good feature. This is an open-drain connection with an on-board pull-up resistor of 100kΩ to the output voltage. Power Good is asserted high approximately 90µs after the output voltage passes 92% of the nominal set voltage. HyperLight Load Mode MIC23156 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 more than the regulation threshold, then the error comparator turns the PMOS off for a minimum-off-time until the output drops below the threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using an NMOS switch instead of a diode allows for lower voltage drop across the switching device when the NMOS 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 MIC23163/4 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases. This provides more energy to the output. This switching scheme improves the efficiency of MIC231563/4 during light load currents by only switching when it is needed. Features Soft-Start Capacitor (C3) The soft start (SS) pin is used to control the output voltage ramp-up time. Setting C3 to 1nF sets the start-up time to the minimum. The start-up time can be determined by Equation 1: TSS = 250 × 10 3 × ln(10 ) × C SS Eq. 1 As the load current increases, the MIC23163/4 goes into continuous conduction mode (CCM) and switches at a frequency centered at 4MHz. The f to calculate the load when the MIC23163/4 goes into continuous conduction mode is approximated by Equation 2: The action of the soft-start capacitor is to control the rise time of the internal reference voltage between 0% and 100% of its nominal steady state value. Feedback Resistors (R1, R2) 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:  (V − VOUT ) × D  ILOAD >  IN  2L × f   R1   VOUT = VREF × 1 +  R2   Eq. 2 As shown in Equation 2, the load at which MIC23163/4 transitions from HyperLight Load mode to PWM mode is a function of the input voltage (VIN), output voltage (VOUT), duty cycle (D), inductance (L), and frequency (f). Where VREF = 0.7V Table 1. Example Feedback Resistor Values VOUT R1 R2 1.2V 215k 301k 1.5V 301k 261k 1.8V 340k 215k 2.5V 274k 107k 3.3V 383k 102k August 23, 2013 2 Revision 1.0 Micrel, Inc. MIC23156 Evaluation Board Evaluation Board Schematic Bill of Materials Item C1 C2 C3 C4 C5 L1 Part Name C1608X5R0J475K Manufacturer TDK (2) GRM188R60J475KE19D Murata C1608X5R0J106K080AB TDK GRM188R60J106ME84D Murata GRM188R71H102MA01D Murata 06035C102KAT2A AVX 06035A150KAT2A GRM1885C1H150JA01D C1608X7R1A105K GRM188R71A105KA61D FLF3215T-R47N LQH32PNR47NNC R1 CRCW0603301KFKEA R2 CRCW0603158KFKEA R3, R4 Description Qty. (1) (3) AVX Murata TDK Murata 4.7µF, 6.3V, X5R, Size 0603 1 10µF, 6.3V, X5R, Size 0603 1 1nF/50V, X7R, 0603 1 15pF, 50V, 0603 1 1µF, 10V, X7R, Size 0603 1 TDK 0.47µH, 2.8A, 21mΩ, L3.2mm x W2.5mm x H1.55mm Murata 0.47µH, 2.9A, 24mΩ, L3.2mm x W2.5mm x H1.55mm (4) Vishay 1 301kΩ, 1%, 1/10W, Size 0603 1 Vishay 158kΩ, 1%, 1/10W, Size 0603 1 CRCW0603100KFKEA Vishay 100kΩ, 1%, 1/10W, Size 0603 1 R5 CRCW060310R0FKEA Vishay 10Ω, 1%, 1/10W, Size 0603 1 U1 MIC23163YMT 4MHz 2A Adjustable Buck Regulator with HyperLight Load Mode 1 (5) Micrel, Inc. Notes: 1. TDK: www.tdk.com. 2. Murata: www.murata.com. 3. AVX: www.avx.com. 4. Vishay: www.vishay.com. 5. Micrel, Inc.: www.micrel.com. August 23, 2013 3 Revision 1.0 Micrel, Inc. MIC23156 Evaluation Board PCB Layout Recommendations Top Layer Bottom Layer August 23, 2013 4 Revision 1.0 Micrel, Inc. MIC23156 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. © 2013 Micrel, Incorporated. August 23, 2013 5 Revision 1.0