MIC2101/02 Evaluation Board 38V, Synchronous Buck Controllers featuring Adaptive On-Time Control Hyper Speed Control™ Family General Description Getting Started The Micrel MIC2101/02 are constant-frequency, synchronous buck controllers featuring a unique adaptive ON-time control architecture. The MIC2101/02 operates over an input supply range of 4.5V to 38V and can be used to supply up to 15A of output current. The output voltage is adjustable down to 0.8V with a guaranteed accuracy of ±1%. The device operates with programmable switching frequency from 200kHz to 600kHz. The MIC2101 is Hyper Light Load® architecture so it operates in pulse skipping mode at light load but from medium load to heavy load it operates in fixed frequency CCM mode. The MIC2102 is Hyper Speed Control™ architecture so it operates in fixed-frequency CCM mode under all load conditions. The basic parameters of the evaluation board are: 1. Input: 5V to 38V 2. Output: 0.8V to 5V at 12A(1) 3. 600kHz Switching Frequency (Adjustable 200kHz to 600kHz) Datasheets and support documentation can be found on Micrel’s web site at www.micrel.com. 1. VIN Supply Connect a supply to the VIN and GND terminals, paying careful attention to the polarity and the supply range (5V < VIN < 38V). Monitor IIN with a current meter and input voltage at VIN and GND terminals with voltmeter. Do not apply power until step 4. 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 100k pull-up resistor (R22) to VIN, which allows the output to be turned on when VDD 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 MIC2101/02 evaluation board. 4. Turn on the Power Turn on the VIN supply and verify that the output voltage is regulated to 3.3V. Note: 1. Refer to the temperature curves shown in “Typical Characteristics”. Requirements The MIC2101 and MIC2102 evaluation board requires only a single power supply with at least 10A current capability. The MIC2101/02 has internal VDD LDO so no external linear regulator is required to power the internal biasing of the IC. In the applications with VIN < +5.5V, VDD should be tied to VIN to by-pass the internal linear regulator. The output load can either be a passive or an active load. Precautions The MIC2103/04 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 38V. Exceeding 38V on the VIN could damage the device. Ordering Information Part Number Description MIC2101YML 12A EV MIC2101 Evaluation Board with up to 5V Output MIC2102YML 12 A EV MIC2102 Evaluation Board with up to 5V Output Hyper Speed Control is a trademark and 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 September 2012 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board Features Feedback Resistors The output voltage on the MIC2101/02 evaluation board, which is preset to 3.3V, is determined by the feedback divider: ⎛ VOUT = VREF × ⎜⎜ 1 + ⎝ ⎞ ⎟ R BOTTOM ⎟⎠ R1 The hiccup sequence including the soft start reduces the stress on the switching FETs and protects the load and supply for severe short conditions. Eq. 1 where VREF = 0.8V, and RBOTTOM is one of R4, R5, R6, R7, R8, R9, R10, R11 which corresponds to 0.9V, 1.0V, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, or 5V. Leaving the RBOTTOM open gives a 0.8V output voltage. All other voltages not listed above can be set by modifying RBOTTOM value according to: RBOTTOM = R1 × VREF VOUT − VREF Eq. 2 Note that the output voltage should not be set to exceed 5V due to the 6.3V voltage rating on the output capacitors. SW Node Test point J1 (VSW) is placed for monitoring the switching waveform, one of the most critical waveforms for the converter. Current Limit The MIC2101/02 uses the RDS(ON) and external resistor connected from ILIM pin to SW node to decides the current limit. In each switching cycle of the MIC2101/02 converter, 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 R17 (VCL) is compared with the drop over the bottom FET generating the short current limit. The small capacitor (C18) 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 R17 and C18 should be much less than the minimum off time. The VCL drop allows programming of short limit through the value of the resistor (RCL), 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. September 2012 Figure 1. MIC2101/02 Current Limiting Circuit The short circuit current limit can be programmed by using the following formula. R17 = (ICLIM − Δ PP × 0.5) × R DS(ON) + VCL ) ICL Eq. 3 where: ICLIM = Desired current limit ΔPP = Inductor current peak-to-peak RDS (ON) = On resistance of low-side power MOSFET VCL = Current-limit threshold, the typical value is 14mV in EC table ICL = Current limit source current, the typical value is 80µA in EC table. 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. 2 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board where: fO = Switching Frequency when R19 is 100k and R20 being open, fO is typically 600kHz. For more precise setting, it is recommended to use the following graph: Switching Frequency 700 R19 = 100k, IOUT =12A 600 V IN = 12V SW FREQ (kHz) The MOSFET RDS(ON) varies 30% to 40% with temperature; therefore, it is recommended to add a 50% margin to ICL in the above equation to avoid false current limiting due to increased MOSFET junction temperature rise. It is also recommended to connect SW pin directly to the drain of the low-side MOSFET to accurately sense the MOSFETs RDS(ON). Loop Gain Measurement The resistor, R14, is placed in series with the regulator feedback path. The control loop gain can be measured by connecting an impedance analyzer across the resistor and selecting the resistor value in between 20Ω to 50Ω. Setting the Switching Frequency The MIC2101/02 are adjustable-frequency, synchronous buck controllers featuring a unique adaptive on-time control architecture. The switching frequency can be adjusted between 200kHz and 600kHz by changing the resistor divider network consisting of R19 and R20. 500 400 V IN = 38V 300 200 100 0 10.00 100.00 1000.00 10000.00 R20 (kΩ ) Figure 3. Switching Frequency vs. R20 The evaluation board design is optimized for a switching frequency of 600kHz. If the switching frequency is programmed to either lower end or higher end, the design needs optimization. Figure 2. Switching Frequency Adjustment The following formula gives the estimated switching frequency: f SW_ADJ = f O × R20 R19 + R20 September 2012 Eq. 4 3 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board MIC2101/02 0.8V to 5V/12A Evaluation Board Typical Characteristics 90 70 60 50 40 90 70 30 20 60 30 20 0 4 8 12 2 6 8 10 12 40 30 14 16 0 fSW = 600kHz (CCM) 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 70 60 50 40 30 4 6 8 10 12 14 16 100 80 70 4 6 8 10 12 90 14 60 50 fSW = 600kHz 70 60 50 4 8 12 September 2012 50 40 30 fSW = 600kHz 0 16 4 8 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 70 60 50 40 30 20 f SW = 600kHz 10 4 8 12 OUTPUT CURRENT (A) 4 16 90 V SW = 600kHz 0 12 Efficiency (VIN = 24V) vs. Output Current (MIC2102) 100 0 OUTPUT CURRENT (A) 16 OUTPUT CURRENT (A) 30 10 30 14 0 40 20 40 0 60 16 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 EFFICIENCY (%) 90 2 Efficiency (VIN = 18V) vs. Output Current (MIC2102) 100 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 12 70 OUTPUT CURRENT (A) Efficiency (VIN = 12V) vs. Output Current (MIC2102) 10 3.3V 2.5V 1.8V 1.5V 1.2V 1.0V 0.9V 0.8V 10 fSW = 600kHz (CCM) 0 OUTPUT CURRENT (A) 8 20 EFFICIENCY (%) 2 6 Efficiency (VIN = 5V) vs. Output Current (MIC2102) 100 0 0 4 80 10 0 2 OUTPUT CURRENT (A) 20 10 fSW = 600kHz (CCM) 90 80 20 EFFICIENCY (%) 4 90 EFFICIENCY (%) EFFICIENCY (%) 50 30 10 Efficiency (VIN = 38V) vs. Output Current (MIC2101) 100 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 60 40 OUTPUT CURRENT (A) 90 70 50 0 0 Efficiency (VIN = 24V) vs. Output Current (MIC2101) 80 60 20 fSW = 600kHz (CCM) OUTPUT CURRENT (A) 100 70 0 16 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 40 10 0 90 50 fSW = 600kHz (CCM) 10 Efficiency (VIN = 18V) vs. Output Current (MIC2101) 100 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 EFFICIENCY (%) 80 EFFICIENCY (%) 100 3.3V 2.5V 1.8V 1.5V 1.2V 1.0V 0.9V 0.8V EFFICIENCY (%) 100 Efficiency (VIN =12V) vs. Output Current (MIC2101) EFFICIENCY (%) Efficiency (VIN = 5V) vs. Output Current (MIC2101) 16 0 0 4 8 12 16 OUTPUT CURRENT (A) M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board MIC2101/02 0.8V to 5V/12A Evaluation Board Typical Characteristics (Continued) Efficiency (VIN = 38V) vs. Output Current (MIC2102) Die Temperature* (VIN = 5.0V) vs. Output Current 100 Die Temperature* (VIN = 12V) vs. Output Current 100 80 EFFICIENCY (%) 70 60 50 DIE TEMPERATURE (°C) 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 40 30 fSW = 600kHz 20 60 40 VIN = 5.0V 20 VOUT = 3.3V 10 80 60 40 VIN = 12V VOUT = 3.3V 20 fSW = 600kHz fSW = 600kHz 0 0 0 4 8 12 16 0 0 1 2 OUTPUT CURRENT (A) 4 5 6 7 8 9 10 11 12 80 60 40 VIN = 24V VOUT = 3.3V fSW = 600kHz 0 0 1 2 3 4 5 6 7 8 9 10 11 12 OUTPUT CURRENT (A) Die Temperature* (VIN = 38V) vs. Output Current 160 DIE TEMPERATURE (°C) 100 20 3 OUTPUT CURRENT (A) Die Temperature* (VIN = 24V) vs. Output Current 120 DIE TEMPERATURE (°C) DIE TEMPERATURE (°C) 90 140 120 100 80 60 VIN = 38V 40 VOUT = 3.3V fSW = 600kHz 20 0 0 1 2 3 4 5 6 7 8 9 OUTPUT CURRENT (A) 10 11 12 0 1 2 3 4 5 6 7 8 9 10 11 12 OUTPUT CURRENT (A) Die Temperature* : The temperature measurement was taken at the hottest point on the MIC2103/04 case mounted on a 5 square inch 4 layer, 0.62”, FR-4 PCB with 2oz. finish copper weight per layer (see Thermal Measurement section). Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components. September 2012 5 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board MIC2101/02 0.8V to 5V/12A Output Evaluation Board Schematic September 2012 6 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board Bill of Materials Item C1 Part Number EEU-FC1J221S C2, C3, C4 Panasonic AVX C3225X7R1H225K TDK(3) AVX C3225X5ROJ107M TDK AVX C1608X7R1H104K TDK C7, C17 C8 AVX C1608X5R0J475K TDK AVX C1608X5R0J105K TDK 08051C474KAT2A GRM188R71H102KA01D C11 C12 Murata AVX 3 100µF/6.3V Ceramic Capacitor, X7R, Size 1210 1 0.1µF/50V Ceramic Capacitor, X7R, Size 0603 3 4.7µF/6.3V Ceramic Capacitor, X7R, Size 0603 2 1µF/6.3V Ceramic Capacitor, X7R, Size 0603 1 0.47µF/100V,X7R,0805 1 1nF/50V Cermiac Capacitor, X7R, Size 0603 1 4.7nF/50V Cermiac Capacitor, X7R, Size 0603 1 Murata 06035C102KAT2A AVX C1608X7R1H102K TDK GRM188R71H472MA01D 2.2µF/50V Ceramic Capacitor, X7R, Size 1210 Murata 06036C105KAT2A GRM21BR72A474KA73 C9 1 Murata 06036D475KAT2A GRM188R70J105KA01D 220µF Aluminum Capacitor, 63V Murata C6, C16, C10 06035C104KAT2A GRM188R60J475KE19D Murata 06035C472KAT2A AVX C1608X7R1H472K TDK Sanyo(5) 470µF/6.3V, 7mΩ, OSCON 6SEPC470M Sanyo 470µF/6.3V, 7mΩ, OSCON C15 (OPEN) 6TPB470M Sanyo 470µF/6.3V, POSCAP C5 (OPEN) GRM32ER60J107ME20L Murata 100µF/6.3V Ceramic Capacitor, X7R, Size 1210 GRM1885C1H150JA01D Murata C13 C18 D1 6SEPC470MX 06035A150JAT2A BAT46W-TP L1 CDEP147NP- 1R5M-95 Qty. Murata(4) 12106D107MAT2A GRM188R71H104KA93D (1) (2) 12105C225KAT2A GRM32ER60J107ME20L C14 Manufacturer Description AVX MCC(6) Sumida (7) 1 15pF, 50V, 0603, NPO 1 100V Small Signal Schottky Diode, SOD123 1 1.5µH, 27/22Asat, 20Arms for 40C rise 1 Notes: 1. Panasonic: www.panasonic.com. 2. AVX: www.avx.com. 3. TDK: www.tdk.com. 4. Murata: www.murata.com. 5. Sanyo: www.sanyo.com. 6. MCC: www.mccsemi.com. 7. Sumida: www.sumida.com. September 2012 7 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board Bill of Materials (Continued) Item Q1, Q3 Part Number BSC067N06LS3 Manufacturer Description Infineon (8) Qty. MOSFET, N-CH, Power SO-8 2 Vishay Dale(9) 10kΩ Resistor, Size 0603, 1% 1 Q2, Q4 (OPEN) R1 CRCW060310K0FKEA R2, R23 CRCW08051R21FKEA Vishay Dale 1.21Ω Resistor, Size 0805, 5% 2 R3 CRCW06035K23FKEA Vishay Dale 5.23K,1%,1/10W,0603. 1 R4 CRCW060380K6FKEA Vishay Dale 80.6kΩ Resistor, Size 0603, 1% 1 R5 CRCW060340K2FKEA Vishay Dale 40.2kΩ Resistor, Size 0603, 1% 1 R6 CRCW060320K0FKEA Vishay Dale 20kΩ Resistor, Size 0603, 1% 1 R7 CRCW060311K5FKEA Vishay Dale 11.5kΩ Resistor, Size 0603, 1% 1 R8 CRCW06038K06FKEA Vishay Dale 8.06kΩ Resistor, Size 0603, 1% 1 R9 CRCW06034K75FKEA Vishay Dale 4.75kΩ Resistor, Size 0603, 1% 1 R10 CRCW06033K24FKEA Vishay Dale 3.24kΩ Resistor, Size 0603, 1% 1 R11 CRCW06031K91FKEA Vishay Dale 1.91kΩ Resistor, Size 0603, 1% 1 R12 (OPEN) CRCW0603715R0FKEA Vishay Dale 715Ω Resistor, Size 0603, 1% R13 (OPEN) CRCW0603348R0FKEA Vishay Dale 348Ω Resistor, Size 0603, 1% R14, R15, R19 CRCW06030000FKEA Vishay Dale 0Ω Resistor, Size 0603, 5% 3 R16 CRCW08052R0FKEA Vishay Dale 2Ω Resistor, Size 0805, 5% 1 R17 CRCW06031K65FKEA Vishay Dale 1.65kΩ Resistor, Size 0603, 1% 1 R18 CRCW060349K9FKEA Vishay/Dale 49.9K,1%,1/10W,0603 1 R20 (OPEN) No Load R21 CRCW060349R9FKEA Vishay Dale 49.9Ω Resistor, Size 0603, 1% 1 R22 CRCW0603100KFKEA Vishay Dale 100kΩ Resistor, Size 0603, 1% 1 MIC2101YML U1 MIC2102YML Micrel. Inc.(10) 38V Synchronous Buck DC/DC Controller 1 Notes: 8. Infineon: www.infineon.com. 9. Vishay: www.vishay.com. 10. Micrel, Inc.: www.micrel.com. September 2012 8 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board Evaluation Board PCB Layout MIC2101/02 Evaluation Board − Copper Layer 1 (Top) MIC2101/02 Evaluation Board − Copper Layer 2 (Mid-Layer 1) September 2012 9 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board Evaluation Board PCB Layout MIC2101/02 Evaluation Board − Copper Layer 3 (Mid-Layer 2) MIC2101/02 Evaluation Board − Copper Layer 4 (Bottom) September 2012 10 M9999-092812-A Micrel, Inc. MIC2101/02 Evaluation Board MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB 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. © 2012 Micrel, Incorporated. September 2012 11 M9999-092812-A