MIC45212 Evaluation Board 26V/14A DC-to-DC Power Module General Description Getting Started Micrel’s MIC45212 is a synchronous step-down regulator module, featuring a unique adaptive ON-time control architecture. The module incorporates a DC-to-DC controller, power MOSFETs, bootstrap diode, bootstrap capacitor, and an inductor in a single package; simplifying the design and layout process for the end user. 1. VIN Supply Connect a supply to the VIN and GND terminals, paying careful attention to the polarity and the supply range (4.5V < VIN < 26V). Monitor IIN with a current meter and monitor input voltage at VIN and GND terminals with a voltmeter. Do not apply power until step 4. This highly integrated solution expedites system design and improves product time-to-market. The internal MOSFETs and inductor are optimized to achieve high efficiency at a low output voltage. The fully optimized design can deliver up to 14A current under a wide input voltage range of 4.5V to 26V, without requiring additional cooling. The MIC45212-1 uses Micrel’s HyperLight Load® (HLL) MIC45212-2 uses Micrel’s Hyper Speed Control™ architecture which enables ultra-fast load transient response, allowing for a reduction of output capacitance. The MIC45212 offers 1% output accuracy that can be adjusted from 0.8V to 5.5V with two external resistors. The basic parameters of the evaluation board are: • Input: 4.5V to 26V • Output: 0.8V to 5V at 14A • 600kHz Switching Frequency (Adjustable 200kHz to 600kHz) Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Requirements The MIC45212-1 and MIC45212-2 evaluation board requires only a single power supply with at least 10A current capability. No external linear regulator is required to power the internal biasing of the IC because the MIC45212 has an internal PVDD LDO. In the applications with VIN < +5.5V, PVDD should be tied to VIN to bypass the internal linear regulator. The output load can either be a passive or an active load. 2. Connect Load and Monitor Output Connect a load to the VOUT and GND terminals. The load can be either a passive (resistive) or an active (as in an electronic load) type. A current meter may be placed between the VOUT terminal and load to monitor the output current. Ensure the output voltage is monitored at the VOUT terminal. 3. Enable Input The EN pin has an on board 100kΩ pull-up resistor (R10) to VIN, which allows the output to be turned on when PVDD exceeds its UVLO threshold. An EN connector is provided on the evaluation board for users to easily access the enable feature. Applying an external logic signal on the EN pin to pull it low or using a jumper to short the EN pin to GND will shut off the output of the MIC45212 evaluation board. 4. Turn Power On Turn on the VIN supply and verify that the output voltage is regulated to 5V. Ordering Information Part Number Description MIC45212-1YMP EV MIC45212-1 Evaluation Board MIC45212-2YMP EV MIC45212-2 Evaluation Board Precautions The MIC45212 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 30V. 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 • http://www.micrel.com March 2, 2015 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board Features Feedback Resistors The output voltage on the MIC45212 evaluation board, which is preset to 5.0V, is determined by the feedback divider: VOUT = VREF × 1 + R BOTTOM R14 All other voltages not listed above can be set by modifying RBOTTOM value according to: RBOTTOM = Eq. 1 R1× VREF VOUT − VREF Eq. 2 Note that the output voltage should not be set to exceed 5V. where VREF = 0.8V, and RBOTTOM is one of R3 thru R9. Leaving the RBOTTOM open by removing all jumpers on the feedback headers gives a 0.8V output voltage. Table 1. Typical Values of Some Components VOUT VIN R14 (Top Feedback Resistor) R (Bottom Feedback Resistor) C12 (Cff) COUT 1.0V 5V to 26V 10kΩ 40.2kΩ 2.2nF 100µF/6.3V 1.2V 5V to 26V 10kΩ 20kΩ 2.2nF 100µF/6.3V 1.5V 5V to 26V 10kΩ 11.5kΩ 2.2nF 100µF/6.3V 1.8V 5V to 26V 10kΩ 8.06kΩ 2.2nF 100µF/6.3V 2.5V 5V to 26V 10kΩ 4.75kΩ 2.2nF 100µF/6.3V 3.3V 5V to 26V 10kΩ 3.24kΩ 2.2nF 100µF/6.3V 5V 7V to 26V 10kΩ 1.9kΩ 2.2nF 100µF/6.3V March 2, 2015 2 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board The short-circuit current limit can be programmed by using the following formula: SW Node Test point J1 (VSW) is placed for monitoring the switching waveform, which is one of the most critical waveforms for the converter. R15 = Current Limit The MIC45212 uses the RDS(ON) of the low-side MOSFET and external resistor connected from the ILIM pin to the SW node to decide the current limit. (ICLIM − DIL (PP ) × 0.5) × R DS(ON) + VCL ICL Eq. 3 ICLIM = Desired current limit RDS(ON) = On-resistance of low-side power MOSFET, 6mΩ (typ.) VCL = Current-limit threshold (typical absolute value is 14mV per the Electrical Characteristics table in MIC45212 datasheet). ICL = Current-limit source current (typical value is 70µA, per the Electrical Characteristics table in MIC45212 datasheet). ΔIL(PP) = Inductor current peak-to-peak, since the inductor is integrated use Equation 4 to calculate the inductor ripple current. The peak-to-peak inductor current ripple is: Figure 1. MIC45212 Current Limiting Circuit ∆IL(PP) = During each switching cycle of the MIC45212, the inductor current is sensed by monitoring the low-side MOSFET in the OFF period. The sensed voltage V(ILIM) is compared with the power ground (PGND) after a blanking time of 150ns. In this way, the drop voltage over the resistor R15 (VCL) is compared with the drop over the bottom FET generating the short current limit. The small capacitor (C15) connected from ILIM pin to PGND filters the switching node ringing during the off-time allowing a better short-limit measurement. The time constant created by R15 and C15 should be much less than the minimum off time. VIN(MAX) × fsw × L Eq. 4 The MIC45212 has 0.6µH inductor integrated into the module. In case of hard short, the short limit is folded down to allow an indefinite hard short on the output without any destructive effect. It is mandatory to make sure that the inductor current used to charge the output capacitance during soft start is under the folded short limit; otherwise the supply will go in hiccup mode and may not be finishing the soft start successfully. The MOSFET RDS(ON) varies 30 to 40% with temperature. Therefore, it is recommended to add a 50% margin to ICLIM in the above equation to avoid false current limiting due to increased MOSFET junction temperature rise. With R15 = 1.69kΩ and C15 = 15pF, the typical output current limit is 16.8A. The VCL drop allows programming of short limit through the value of the resistor (R15) if the absolute value of the voltage drop on the bottom FET is greater than VCL. In that case the V(ILIM) is lower than PGND and a short circuit event is triggered. A hiccup cycle to treat the short event is generated. The hiccup sequence including the soft start reduces the stress on the switching FETs and protects the load and supply for severe short conditions. March 2, 2015 VOUT × (VIN(MAX) − VOUT ) 3 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board Setting the Switching Frequency The MIC45212 switching frequency can be adjusted by changing the value of resistors R1 and R2. The switching frequency also depends on VIN, VOUT, and load conditions. R2 is selected to set the required switching frequency as shown in Figure 3: Switching Frequency 800 700 VOUT = 5V VIN = 12V SW FREQ (kHz) 600 500 400 300 200 R1 = 100kΩ 100 0 10.00 Figure 2. Switching Frequency Adjustment R2 R1 + R2 1000.00 10000.00 R2 (kΩ) Figure 3. Switching Frequency vs. R2 The following formula gives the estimated switching frequency: fSW = fO × 100.00 Eq. 5 Where fO = 600kHz R1 = 100kΩ (recommended) March 2, 2015 4 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board MIC45212 Evaluation Board Schematic March 2, 2015 5 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board Bill of Materials Item Part Number C1 B41125A7227M000 C2, C3, C17 C3216X5R1H106M160AB Manufacturer TDK (2) TDK (3) Description Qty. 220µF/35V, ALE Capacitor (optional) 1 10uF/50V, 1206, X5R, 10%, MLCC 3 0.1µF/50V, X7R, 0603, 10%, MLCC 4 C4, C16, C9, C15 GRM188R71H104KA93D Murata C5, C6 C3216X5R0J107M160AB TDK 100µF/6.3V, X5R, 1206, 20%, MLCC 2 C12 C1608C0G1H222JT TDK 2.2nF/50V, NP0, 0603, 5%, MLCC 1 C15 GRM1885C1H150JA01D 15pF/50V, NP0, 0603, 5%, MLCC 1 0Ω Resistor, 1%, 1/10W, 0603, Thick Film 3 Murata R17, R18, R19 RCG06030000Z0EA R3 CRCW060340K2FKEA Vishay Dale 40.2kΩ, 1%, 1/10W, 0603, Thick Film 1 R4 CRCW06020K0FKEA Vishay Dale 20kΩ, 1%, 1/10W, 0603, Thick Film 1 R5 CRCW060311K5FKEA Vishay Dale 11.5kΩ, 1%, 1/10W, 0603, Thick Film 1 R6 CRCW06038K06FKEA Vishay Dale 8.06kΩ, 1%, 1/10W, 0603, Thick Film 1 R7 CRCW06034K75FKEA Vishay Dale 4.75kΩ, 1%, 1/10W, 0603, Thick Film 1 R8 CRCW06033K24FKEA Vishay Dale 3.24kΩ, 1%, 1/10W, 0603, Thick Film 1 R9 CRCW06031K91FKEA Vishay Dale 1.91kΩ, 1%, 1/10W, 0603, Thick Film 1 R1, R10 CRCW0603100K0FKEA Vishay Dale 100kΩ, 1%, 1/10W, 0603, Thick Film 2 R11 CRCW060349K9FKEA Vishay Dale 49.9kΩ, 1%, 1/10W, 0603, Thick Film 1 R14 CRCW060310K0FKEA Vishay Dale 10kΩ, 1%, 1/10W, 0603, Thick Film 1 R15 CRCW06031K69FKEA Vishay Dale 1.69kΩ, 1%, 1/10W, 0603, Thick Film 1 Header 2x7 1 Header 2 6 Single End, Through Hole, Terminal 8 15A, 4 prong through hole screw terminal 4 R2, R12, R13, R16 Open 4 C7, C8, C14, C10, C13 Open 5 26V/14A DC-to-DC Power Module 1 J1 J2-J4, TP1, TP3, TP5 M50-3500742 90120-0122 TP7 − TP14 1502-2 CON1, CON2, CON3, CON4 8191k U1 MIC45212-1YMP MIC45212-2YMP Vishay Dale (4) (5) Harwin (6) Molex Keystone (7) Keystone Micrel, Inc.(1) Notes: 1. Micrel, Inc.: www.micrel.com. 2. TDK: www.TDK.com. 3. Murata: www.murata.com. 4. Vishay-Dale: www.vishay.com. 5. Harwin: http://www.harwin.com. 6. Molex: www.molex.com. 7. Keystone: www.keyelco.com. March 2, 2015 6 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board PCB Layout Recommendations MIC45212 Evaluation Board Top Layer MIC45212 Evaluation Board Copper Layer 2 March 2, 2015 7 Revision 2.0 Micrel, Inc. MIC45212 Evaluation Board PCB Layout Recommendations (Continued) MIC45212 Evaluation Board Copper Layer 3 MIC45212 Evaluation Board Bottom Layer March 2, 2015 8 Revision 2.0 Micrel, Inc. MIC45212 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. March 2, 2015 9 Revision 2.0