MIC2174 3A Evaluation Board Constant Frequency, Synchronous Buck Controller Featuring Adaptive OnTime Control Hyper Speed ControlTM Family General Description TM MIC2174, a member of the new Hyper Speed Control family of buck controllers introduced by Micrel, is a synchronous, adaptive on-time buck controller. This controller is targeted for cost sensitive applications requiring high performance. The MIC2174 operates over an input supply range of 3V to 40V, and is independent of the IC supply voltage. Data sheets support documentation can be found on Micrel’s web site at www.micrel.com. Requirements The MIC2174 evaluation board requires two power supplies: one to provide VIN (connect to HSD pin of MIC2174), and the other to provide VDD (connect to IN pin of the MIC2174) for the control circuitry. The VIN power supply should be able to deliver greater than 3.0V at over 3A. The VDD power source, which is recommended to be 5.0V typical, should be able to deliver greater than 3.0V. The typical VDD current is a few milliamps. An external 20mA minimum power supply is recommended for VDD. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN or VDD terminal may damage the device. In addition, the maximum VIN operating voltage of the MIC2174 evaluation board is 40V, and the maximum VDD operation voltage is 5.5V. Exceeding 42V on VIN or exceeding 6V on VDD could damage the device. An external VDD power supply is required and it should be turned on no earlier than VIN power supply to make sure the soft-start behavior properly. Getting Started 1. Connect an external supply to VIN terminal. Apply desired input voltage to the VIN (J1) and ground (J4) terminals of the evaluation board, paying careful attention to polarity and supply voltage (3.0V<VIN<40V). An ammeter may be placed between the input supply and the VIN terminal to the evaluation board. Ensure the supply voltage is monitored at the VIN terminal. The ammeter and/or power lead resistance can reduce the voltage supplied to the input. 2. Connect an external supply to VDD terminal. Apply desired input voltage to the VDD (J6) and ground (J5) terminals of the evaluation board, paying careful attention to polarity and supply voltage (3.0V<VDD<5.5V). The VDD power supply should be turned on no earlier than VIN power supply. The recommended voltage for VIN is 5V. 3. Connect the load to the VOUT and ground terminals. The load can be either passive (resistive) or active (as in an electronic load). An ammeter can be placed between the load and the VOUT (J2) terminal. Ensure the output voltage is monitored at the VOUT terminal. The default VOUT is set to 1.8V. This can be adjusted by changing the feedback resistors. See “Output Voltage.” 4. Enable the MIC2174. The enable pin is floating by default. The output of the MIC2174 turns on when VDD exceeds the UVLO threshold. The output of the MIC2174 may be turned off by shorting the enable pin to ground or bringing the enable pin below the enable threshold. An external connection on the board provides easy access to the enable pin. Output Voltage The output voltages on the MIC2174 evaluation board are adjustable. The output voltage is controlled by the feedback resistors (R4 and R6) and can be calculated as follows: VOUT = VREF × (1 + R4 ) R6 where VREF = 0.8V. The evaluation board is preset at a 1.8V output, but can easily be modified by removing R6 and replacing it with the value that yields the desired output voltage. R6 = R 4 × VREF VOUT − VREF For VREF = 0.8V, this reduces to: 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 December 2009 M9999-122309-A Micrel, Inc. MIC2164 5A Evaluation Board R 4 × 0 .8 V VOUT − 0.8 V Ensure the output voltage set does not exceed 5V, since the output capacitor has a 6.3V voltage rating. When the output voltage greater than 5V is desired, the output capacitor should be replaced with higher voltage rating. Ordering Information R6 = December 2009 2 Part Number Description Package MIC2174-1YMM MIC2174-1YMM 3A EV IC 10-pin MSOP Evaluation Board 10-pin MSOP M9999-122309-A Micrel, Inc. MIC2174 3A Evaluation Board Bill of Materials Item C1 C2 C4,C5,C13 Part Number B41112A8336M 12105C475KAZ2A GRM32ER71H475KA88L 12106D107MAT2A GRM32ER60J107ME20L 06035C104KAT2A C3, C6, C8, C10 GRM188R71H104KA93D C1608X7R1H104K 0805ZC225MAT2A C7 GRM21BR71A225KA01L C2012X7R1A225K 06035C102KAT2A C11 C12 D1 L1 December 2009 GRM188R71H102KA01D Manufacturer EPCOS (1) Qty 33µF Aluminum Capacitor, SMD, 63V 1 4.7µF Ceramic Capacitor, X7R, Size 1210, 50V 1 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 3 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V 4 2.2µF Ceramic Capacitor, X7R, Size 0805, 10V 1 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 10nF Ceramic Capacitor, X7R, Size 0603, 50V 1 Small Signal Schottky Diode 1 10µH Inductor, 3.8A Saturation Current 1 (2) AVX Murata (3) AVX Murata AVX Murata TDK (4) AVX Murata TDK AVX Murata C1608X7R1H102K TDK 06035C103KAZ2A AVX GRM188R71H103K Murata C1608X7R1H103K TDK SD103AWS-7 Description Diodes Inc (5) (6) SD103AWS Vishay CDRH104RNP-100 Sumida (7) 3 M9999-122309-A Micrel, Inc. MIC2174 3A Evaluation Board 60V 7.5A N-Channel MOSFET 26.5mΩ Rds(on) @ 4.5V 1 Vishay Dale 2.21Ω Resistor, Size 0603, 1% 1 CRCW06031R21FKEA Vishay Dale 1.21Ω Resistor, Size 0603, 1% 1 R3 CRCW060319K6FKEA Vishay Dale 19.6kΩ Resistor, Size 0603, 1% 1 R4 CRCW060310K0FKEA Vishay Dale 10kΩ Resistor, Size 0603, 1% 1 R5 CRCW060320R0FKEA Vishay Dale 20Ω Resistor, Size 0603, 1% 1 R6 CRCW06038K06FKEA Vishay Dale 8.06kΩ Resistor, Size 0603, 1% 1 300kHz Buck Controller 1 Q1,Q2 FDS5682 R1 CRCW06032R21FKEA R2 U1 MIC2174YMM Fairchild (8) (9) Micrel. Inc. Notes: 1. EPCOS: www.epcos.com 2. AVX: www.avx.com 3. Murata: www.murata.com 4. TDK: www.tdk.com 5. Diodes Inc: www.diodes.com 6. Vishay: www.vishay.com 7. Sumida: www.sumida.com 8. Fairchild: www.fairchildsemi.com 9. Micrel, Inc.: www.micrel.com December 2009 4 M9999-122309-A Micrel, Inc. MIC2174 3A Evaluation Board Printed Circuit Board Layouts Figure 1a. Top Layer Figure 1b. Bottom Layer December 2009 5 M9999-122309-A Micrel, Inc. MIC2174 3A Evaluation Board Figure 1c. Mid Layer 1 (GND Plane) Figure 1d. Mid Layer 2 December 2009 6 M9999-122309-A Micrel, Inc. MIC2174 3A 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 The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. 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. © 2009 Micrel, Incorporated. December 2009 7 M9999-122309-A