MIC23603YML-EV

MIC23603 Evaluation Board 4MHz PWM 6A Buck Regulator with Hyper Light Load® General Description Getting Started The MIC23603 evaluation board allows the customer to evaluate the MIC23603, a fully-integrated 6A, 4MHz switching regulator that features Hyper Light Load® mode, a power good output indicator, and programmable softstart. The MIC23603 is highly efficient throughout the output current range, drawing just 24µA of quiescent current in operation. The tiny 4mm × 5mm DFN package saves precious board space and requires few external components. The MIC23603 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 (J1) terminal and GND (J2). Requirements The MIC23603 evaluation board requires a single 40W bench power source adjustable from 2.7V to 5.5V. The loads can be either active (electronic load) or passive (resistor), and must be able to dissipate 30W. 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 voltage. 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 make sure correct polarity is observed. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. 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 (J1) terminal. Be sure to monitor the supply voltage at the VIN (J1) terminal, as the ammeter and/or power lead resistance can reduce the voltage supplied to the device. 2. Connect a load to the VOUT (J4) and ground (J3) terminals. The load can be either active 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 (J4) terminal. The board has a 2-pin connector (TP1) to allow for output voltage monitoring. 3. Enable the MIC23603. The MIC23603 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 0.4V to the EN (J6) terminal. 4. Power Good. The board provides a power good test point (J5) to monitor the power good function. The power good output goes high (VOUT) approximately 40µs after the output voltage reaches 90% of its nominal voltage. Ordering Information Part Number Description MIC23603YML EV Adjustable Output Evaluation Board Hyper Light 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 November 13, 2014 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board Evaluation Board Examples of values are illustrated in Table 1. Table 1. Example Values for VOUT, R3, and R4 VOUT R3 R4 1.2V 274kΩ 294kΩ 1.5V 316kΩ 221kΩ 1.8V 560kΩ 294kΩ 2.5V 324kΩ 107kΩ 3.3V 464kΩ 107kΩ The feed-forward capacitor, C10, can be fitted to improve transient performance. This improves transients by injecting 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. A typical value range of 33pF to 68pF is recommended. Power Good (PG) The evaluation board has a test point provided to the right of EN for testing PG. This is an open-drain connection to the output voltage with an on-board pull-up resistor of 100kΩ. This is asserted high approximately 40µs after the output voltage passes 90% of the nominal set voltage. Figure 1. MIC23603 Evaluation Board – Top Layer Other Features Hyper Light Load Mode MIC23603 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 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 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 MIC23603 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases, which provides more energy to the output. This switching scheme improves the efficiency of MIC23603 during light load currents by switching only when it is needed. As the load current increases, the MIC23603 goes into continuous conduction mode (CCM) and switches at a frequency centered at 4MHz. Soft-Start Capacitor The soft-start (SS) pin is used to control the output voltage ramp-up time. Setting C4 to 2.2nF sets the start-up time to the minimum. The start-up time can be determined by: TSS = 250 × 103 × In(10) × CSS Eq.1 The soft-start capacitor controls the rise time of the internal reference voltage between 0% and 100% of its nominal steady state value. Feedback Resistors (R3, R4) for Adjustable Output The output voltage is set nominally to 1.8V. This output can be changed by adjusting the upper resistor, R3, in the feedback potential divider. Therefore: R3 = R4 × (VO − VREF)/VREF Eq. 2 where VREF = 0.62V. November 13, 2014 2 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board Refer to Equation 3 to calculate the load when the MIC23603 goes into continuous conduction mode: ILOAD >  VIN − VOUT × D    2L × f   Eq. 3 Equation 3 illustrates that the load at which MIC23603 transitions from Hyper Light Load mode to PWM mode is a function of the input voltage (VIN), output voltage (VOUT), duty cycle (D), inductance (L), and frequency (f). The “Switching Frequency vs. Load” graph (see Evaluation Board Performance section) shows that, as the output current increases, the switching frequency also increases until the MIC23603 goes from Hyper Light Load mode to PWM mode at approximately 300mA. The MIC23603 will switch at a relatively constant frequency around 4MHz after the output current is over 300mA. November 13, 2014 3 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board Evaluation Board Performance Efficiency Vs. Output Current Switching Frequency Vs Load Current 10000 100 100 VOUT=3.3V 90 VIN=2.9V 10 VIN=3.6V 1 VOUT=1.8V L=0.33µH COUT=2x47µF 0.1 0.0001 0.001 0.01 0.1 1 80 VOUT=2.5V 70 Efficiency (%) 100 VIN=5V 90 80 EFFICIENCY (%) 1000 FREQUENCY (kHz) Efficiency vs. Load 1.8vout 60 50 40 30 20 0 0.0001 10 0.001 LOAD CURRENT (A) 0.01 0.1 1 50 VIN=3.6V VIN=5V VIN=2.9V 40 30 L=0.33µF COUT=2x47µF 10 10 OUTPUT CURRENT (A) VOUT Rise Time vs Css 60 20 VIN=5V L=0.33µH COUT=2x47µF 10 70 0 0.0001 0.001 0.01 0.1 1 10 LOAD CURRENT(A) Enable Thresholds Vs. Input Voltage 1.10 ENABLE THRESHOLD (V) 1000000 100000 Rise Time (us) 10000 1000 100 1.05 ENABLE ON 1.00 0.95 ENABLE OFF 0.90 0.85 VOUT=1.8V LOAD=150mA 10 VIN=3.6V 1 1000 0.80 2.5 10000 100000 1000000 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) Css (pF) November 13, 2014 4 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board Evaluation Board Schematic November 13, 2014 5 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board Bill of Materials Item Part Number 06036D106MAT2A C1, C2, C7, C8 GRM188R60J106ME47D C1608X5R0J106M 04026D105KAT2A C3, C11, C14 C4 C5,C6 GRM155R60J105KE19D C10 C12 C13 L1 Murata(2) 4 1µF/6.3V, X5R, 0402 4 2.2nF/50V, 0402 1 47µF/6.3V, X5R,1206 2 Capacitor, Alum, 220µF, 10V, 20% Radial 1 68pF, 50V, NPO,0402 1 4.7µF, 6.3V, X5R, 0402 1 0.1µF/6.3V, X7R, 0402 1 TDK AVX Murata AVX Murata C1005C0G1H223J TDK 12066D476MAT2A AVX C3216X6S1A476M TDK Murata Panasonic(4) 04025A680JAT2A AVX C1005C0G1H680J TDK GRM1555C1H680JZ01D Murata GRM155R60J475ME47D Murata 04026D475KAT2A AVX 04026C104KAT2A AVX C1005X7R0J104K TDK GRM155R70J104KA01D Murata IHLP2020CZERR33M01 Vishay(5) CDMC6D28NP-R30MC 10µF/6.3V, X5R, 0603 (3) 04025A223JAT2A ECA-1AHG221 Qty. AVX TDK GRM1555C1H223JA01D Description (1) C1005X5R0J105K GRM31CR60J476ME19L C9 Manufacturer (6) Sumida 0.33µH, 13.7A , 4.3mΩ 0.3µH, 16.1A, 2.7mΩ 1 R1, R2 CRCW0402100KFKED Vishay/Dale 100KΩ, 1%, 1/16W, 0402 2 R3 CRCW0402560KFKEA Vishay/Dale 560KΩ, 1%, 1/6W, 0402 1 R4 CRCW0402294KFKEA Vishay/Dale 294KΩ, 1%, 1/10W, 0402 1 R5 CRCW040210R0FKED Vishay/Dale 10Ω, 1%, 1/16W, 0402 1 Vishay/Dale 3Ω, 1%, 1/10W, 0603 1 4MHz PWM 6A Buck Regulator with Hyper Light Load 1 R6 U1 MIC23603YML Micrel, Inc.(7) Notes: 1. AVX: www.avx.com. 2. Murata: www.murata.com. 3. TDK: www.tdk.com. 4. Panasonic: www.panasonic.com. 5. Vishay: www.vishay.com. 6. Sumida: www.sumida.com. 7. Micrel, Inc.: www.micrel.com. November 13, 2014 6 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board PCB Layout Recommendations Top Layer Layer 2 November 13, 2014 7 Revision 1.1 Micrel, Inc. MIC23603 Evaluation Board PCB Layout Recommendations (Continued) Layer 3 Bottom Layer November 13, 2014 8 Revision 1.1 Micrel, Inc. MIC23603 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, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products. Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network of distributors and reps worldwide. Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. 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.” © 2014 Micrel, Incorporated. November 13, 2014 9 Revision 1.1