MIC23201 2MHz PWM 2A Buck Regulator with Hyper Speed Control™ General Description Features The MIC23201 is a high efficiency 2MHz 2A synchronous buck regulator with Hyper Speed Control. Micrel’s Hyper Speed Control provides ultra-fast transient response which is perfectly suited for supplying processor core voltages. An additional benefit of this proprietary architecture is very low output ripple voltage throughout the entire load range with the use of small output capacitors. The tiny 3mm x 3mm MLF® package saves precious board space and requires only three external components. The MIC23201 is designed for use with a very small inductor, down to 1µH, and an output capacitor as small as 22µF that enables a total solution size, less than 1.5mm height. The MIC23201 provides a constant switching frequency around 2MHz while achieving peak efficiencies up to 90%. The MIC23201 is available in 10-pin 3mm x 3mm MLF package with an operating junction temperature range from –40C to +125C. Datasheets and support documentation can be found on Micrel’s web site at: www.micrel.com. Input voltage: 2.7V to 5.5V 2A output current Up to 90% peak efficiency Programmable Soft-Start Power Good Indicator 2MHz switching frequency Safe for pre-biased output Ultra fast transient response Low voltage output ripple, 16mV at full load Fully integrated MOSFET switches 0.01µA shutdown current Thermal shutdown and current limit protection Output Voltage as low as 0.95V 10-pin 3mm x 3mm MLF –40C to +125C operating junction temperature range Applications Low Voltage Point of Load Blu Ray DVD Players Networking Equipment Set Top Boxes ____________________________________________________________________________________________________________ Typical Application Efficiency (VIN = 3.3V) vs. Output Current 100 90 EFFICIENCY (%) 80 2.5V 1.8V 1.5V 1.2V 0.95V 70 60 50 40 30 20 10 VIN = 3.3V 0 0 0.6 1.2 1.8 2.4 3 OUTPUT CURRENT (A) Hyper Speed Control is a trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademark Amkor Technology 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 2012 M9999-082912-A Micrel Inc. MIC23201 Ordering Information Part Number Marking Code Nominal Output Voltage MIC23201YML 201A ADJ Package 10-pin 3mm x 3mm MLF Junction Temp. Range -40C to +125C Lead Finish Pb-Free Notes: 1. Other options available. Contact Micrel for details. 2. MLF is GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 10 Pin 3mm x 3mm MLF (ML) (Top View) Pin Description Pin Number Pin Name 1 SW Switch output: Internal power MOSFET output switches. 2 EN Enable input: Logic high enables operation of the regulator. Logic low will shut down the device. Do not leave floating. 3 SNS Sense input: Connect to VOUT as close to output capacitor as possible to sense output voltage. 4 FB Feedback input: The FB pin is regulated to 0.62V. Connect a resistor divider from the output to ground to set the output voltage. 5 PG Power Good output: Open Drain output for the power good indicator. Place a resistor between this pin and a voltage source to detect a power good condition. 6 SS Soft Start: Place a capacitor from SS pin to ground to program the soft start time. Do not leave this pin floating. Minimum of 100pF CSS is required. 7 AGND Analog Ground: Connect to central ground point where all high current paths meet (CIN, COUT, PGND) for best operation. 8 SVIN Signal input voltage: This pin is connected externally to the VIN pin. A 2.2µF ceramic capacitor from the SVIN pin to AGND must be placed next to the IC. 9 VIN 10 PGND Power Ground. EP ePad Thermal pad. It must be connected to PGND on the PCB to improve the thermal performance. August 2012 Pin Function Power supply input voltage: The VIN pin is the input supply to the internal P-Channel Power MOSFET. A 22µF ceramic is recommended for bypassing at VIN pin. 2 M9999-082912-A Micrel Inc. MIC23201 Absolute Maximum Ratings (1) Operating Ratings (2) Supply Voltage (VIN, SVIN)……………………………... ..6V Sense (VSNS).. ..................................................................6V Power Good (PG)……................................................. ....6V Output Switch Voltage ……………………………..…….6V Enable Input Voltage (VEN)............................... -0.3V to VIN Storage Temperature Range………………-65C to +150C ESD Rating(3) ……………………………………………….1kV Supply Voltage (VIN) ... …………………………..2.7V to 5.5V Enable Input Voltage (VEN) .. ……………………….0V to VIN Output Voltage Range (VSNS) ………………….0.95V to 3.6V Junction Temperature Range (TJ) .... ….-40C TJ +125C Thermal Resistance 3mm x 3mm MLF-10 (JA) .............................60.7C/W 3mm x 3mm MLF-10 (JC) .............................28.7C/W Electrical Characteristics (4) TA = 25°C; VIN = VEN = 3.3V; L = 1.0µH; COUT = 22µF unless otherwise specified. Bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted. Parameter Condition Min Supply Voltage Range Under-Voltage Lockout Threshold Typ 2.7 VIN Rising 2.45 Under-Voltage Lockout Hysteresis 2.55 Max Units 5.5 V 2.65 V 200 mV Quiescent Current IOUT = 0mA , SNS > 1.2 * VOUT Nominal 1.15 3.35 mA Shutdown Current VEN = 0V; VIN = 5.5V 1.34 5 µA Feedback Voltage ILOAD = 20mA 0.62 0.635 V 0.604 Feedback Bias Current Current Limit Output Voltage Line Regulation Output Voltage Load Regulation PWM Switch ON-Resistance SNS = 0.9*VOUTNOM 2.3 1 µA 4.4 A 0.3 %/V 0.46 % 0.71 % VIN = 3.6V to 5.5V if VOUTNOM < 2.5V, ILOAD = 20mA VIN = 4.5V to 5.5V if VOUTNOM ≥ 2.5V, ILOAD = 20mA 20mA < ILOAD < 500mA, VIN = 3.6V if VOUTNOM < 2.5V 20mA < ILOAD < 500mA, VIN = 5.0V if VOUTNOM ≥ 2.5V 20mA < ILOAD < 1A, VIN = 3.6V if VOUTNOM < 2.5V 20mA < ILOAD < 1A, VIN = 5.0V if VOUTNOM ≥ 2.5V ISW = 100mA PMOS 0.200 ISW = -100mA NMOS 0.190 Switching Frequency IOUT = 120mA 2 MHz Maximum Duty Cycle VFB = 0V Soft Start Time VOUT = 90%, CSS=470pF 300 µs Soft Start Current VSS = 0V 2.7 µA Power Good Threshold (Rising) % of VNOMINAL 80 85 % 90 95 % Power Good Hysteresis 7 % Power Good Delay 68 µs 85 Ω Power Good Pull Down Resistance IPG = 250µA Enable Threshold Turn-On 0.5 Enable Input Current Over Temperature Shutdown TJ Rising Over Temperature Shutdown Hysteresis 0.9 1.2 V 0.1 2 µA 160 C 20 C Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF. 4. Specification for packaged product only. August 2012 3 M9999-082912-A Micrel Inc. MIC23201 Typical Characteristics 30 20 VOUT = 1.8V IOUT = 0A SWITCHING 0 0.640 7.0 FEEDBACK VOLTAGE (V) 40 10 6.0 5.0 4.0 3.0 2.0 1.0 3.0 3.5 4.0 4.5 5.0 3.0 INPUT VOLTAGE (V) 4.0 4.5 5.0 5.5 2.5 1.0% 0.8% 0.6% 0.4% 8 6 4 2 VOUT = 1.8V IOUT = 0A to 2A 0 4.5 5.0 5.5 3.0 3.5 4.0 4.5 2200 2000 1800 1600 VOUT = 1.8V IOUT = 0A 4.0 4.5 INPUT VOLTAGE (V) August 2012 5.0 5.0 5.5 Falling 0.40 0.20 2.5 3.0 5.5 3.5 4.0 4.5 INPUT VOLTAGE (V) Power Good Threshold/VREF Ratio vs. Input Voltage 100 1.25 1.00 0.75 0.50 0.25 2.5 3.0 3.5 4.0 4.5 5.0 90 80 70 60 50 40 30 20 10 VREF = 0.62V 0 VEN = VIN 0.00 1000 3.5 5.5 0.60 5.5 VPG THRESHOLD/VREF (%) ENABLE INPUT CURRENT (µA) 2400 3.0 5.0 1.50 2600 2.5 0.80 Enable Input Current vs. Input Voltage 2800 1200 5.0 Rising 1.00 INPUT VOLTAGE (V) Switching Frequency vs. Input Voltage 1400 4.5 0.00 2.5 INPUT VOLTAGE (V) 3000 4.0 VOUT = 1.8V 0.0% 4.0 3.5 Enable Threshold vs. Input Voltage 1.20 ENABLE THRESHOLD (V) 1.2% 3.5 3.0 INPUT VOLTAGE (V) 1.4% CURRENT LIMIT (A) OUTPUT REGULATION (%) 3.5 10 3.0 0.608 VOUT = 1.8V Current Limit vs. Input Voltage 1.6% 2.5 0.616 INPUT VOLTAGE (V) Output Regulation vs. Input Voltage 0.2% 0.624 0.600 2.5 5.5 0.632 VEN = 0V 0.0 2.5 SWITCHING FREQUENCY (kHz) Feedback Voltage vs. Input Voltage 8.0 SHUTDOWN CURRENT (µA) 50 SUPPLY CURRENT (mA) VIN Shutdown Current vs. Input Voltage VIN Operating Supply Current vs. Input Voltage 2.5 5.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 4 M9999-082912-A Micrel Inc. MIC23201 Typical Characteristics (Continued) SHUTDOWN CURRENT (µA) VOUT = 1.8V IOUT = 0A SWITCHING 30 20 10 0 -25 0 0.640 25 50 75 100 VIN = 3.3V 8 IOUT = 0A 7 VEN/DLY = 0V 5 4 3 2 2.8 2.7 Rising 2.6 2.5 2.4 Falling 2.3 1 2.2 -25 0 25 50 75 100 125 -50 -25 0 25 50 TEMPERATURE (°C) TEMPERATURE (°C) Feedback Voltage vs. Temperature Load Regulation vs. Temperature Line Regulation vs. Temperature 2.0% 0.624 0.616 VIN = 3.3V 0.608 VOUT = 1.8V 1.6% 1.4% 1.2% 1.0% 0.8% 0.6% VIN = 3.3V 0.4% VOUT = 1.8V 0.2% 0.600 0 25 50 75 100 125 VOUT = 1.8V 0.00% -0.50% -1.00% -1.50% IOUT = 0A to 2A 0.0% -25 -2.00% -50 -25 TEMPERATURE (°C) 0 25 50 75 100 125 -50 TEMPERATURE (°C) Switching Frequency vs. Temperature -25 0 25 50 75 100 125 TEMPERATURE (°C) Current Limit vs. Temperature Enable Threshold vs. Temperature 3000 125 VIN = 2.7V to 5.5V LINE REGULATION (%) 0.632 100 0.50% 1.8% -50 75 TEMPERATURE (°C) IOUT = 0A 1.20 10 VIN = 3.3V 2800 ENABLE THRESHOLD (V) SWITCHING FREQUENCY (kHz) 2.9 6 -50 125 LOAD REGULATION (%) FEEDBACK VOLTAGE (V) 9 0 -50 VIN UVLO Threshold vs. Temperature 3.0 2600 2400 2200 2000 1800 1600 VIN = 3.3V 1400 VOUT = 1.8V 1200 1.10 CURRENT LIMIT (A) SUPPLY CURRENT (mA) VIN =3.3V 40 VIN Shutdown Current vs. Temperature 10 50 VIN THRESHOLD (V) VIN Operating Supply Current vs. Temperature 1.00 Rising 0.90 Falling 0.80 8 6 4 2 VIN = 3.3V VOUT = 1.8V IOUT = 0A 1000 -50 -25 0 25 50 75 TEMPERATURE (°C) August 2012 100 125 0 0.70 -50 -25 0 25 50 75 TEMPERATURE (°C) 5 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) M9999-082912-A Micrel Inc. MIC23201 Typical Characteristics (Continued) Enable Input Current vs. Temperature Feedback Voltage vs. Output Current 0.00% 0.80 0.60 0.40 VIN = 3.3V VEN = VIN 0.20 0.640 0.630 0.620 0.610 VIN = 3.3V 0.600 -25 0 25 50 75 100 0.5 TEMPERATURE (°C) 2600 80 EFFICIENCY (%) SWITCHING FREQUENCY (kHz) 90 2400 2200 2000 1800 1600 1.5 1000 1.0 1.5 2.0 70 60 50 2.0 70 60 50 40 30 20 VIN = 3.3V VIN = 5V 10 0 0.6 1.2 1.8 2.4 3 0 0.6 1.2 1.8 2.4 3 OUTPUT CURRENT (A) Output Voltage vs. Load Current VOUT Rise Time vs. CSS 1000000 70 5.0VIN 50 40 30 20 10 100000 1.600 1.400 RISE TIME (µs) OUTPUT VOLTAGE (V) 1.800 80 1.200 1.000 0.800 0.600 0.400 0 1 1.5 2 1000 100 VIN = 3.3V VOUT = 1.8V 0.000 OUTPUT CURRENT (A) 10000 10 VIN = 3.3A 0.200 VOUT = 1.8V August 2012 1.5 3.6V 3.3V 2.7V 2.5V 1.8V 1.5V 1.2V 0.95V OUTPUT CURRENT (A) 3.3VIN 1.0 100 30 2.000 0.5 0.5 Efficiency (VIN = 5V) vs. Output Current 40 0 100 0 -1.60% 80 Efficiency vs. Output Current 60 -1.40% OUTPUT CURRENT (A) 2.5V 1.8V 1.5V 1.2V 0.95V OUTPUT CURRENT (A) 90 -1.20% 0.0 0 0.5 -1.00% 90 10 VOUT = 1.8V 0.0 -0.80% 2.0 20 VIN = 3.3V 1200 1.0 Efficiency (VIN = 3.3V) vs. Output Current 100 2800 1400 V OUT = 1.8V -0.60% OUTPUT CURRENT (A) Switching Frequency vs. Output Current 3000 V IN = 2.7V to 5.5V -0.40% -2.00% 0.0 125 EFFICIENCY (%) -50 -0.20% -1.80% VOUT = 1.8V 0.00 EFFICIENCY (%) LINE REGULATION (%) 0.650 FEEDBACK VOLTAGE (V) ENABLE INPUT CURRENT (µA) 1.00 Line Regulation vs. Output Current 0.0 1.0 2.0 3.0 LOAD CURRENT (A) 6 4.0 5.0 1 100 VOUT = 1.8V 1000 10000 100000 1000000 CSS (pF) M9999-082912-A Micrel Inc. MIC23201 Typical Characteristics (Continued) Case Temperature* (VIN = 3.3V) vs. Output Current Case Temperature* (VIN = 5.0V) vs. Output Current 100 DIE TEMPERATURE (°C) DIE TEMPERATURE (°C) 100 80 60 40 20 VIN = 3.3V 80 60 40 20 VIN = 5V VOUT = 1.8V VOUT = 1.8V 0 0 0.0 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0 0.0 0.5 1.0 1.5 2.0 OUTPUT CURRENT (A) Die Temperature* : The temperature measurement was taken at the hottest point on the MIC23201 case and mounted on a 1.4-square inch PCB (see Thermal Measurements section). Actual results will depend upon the size of the PCB, ambient temperature, and proximity to other heat-emitting components. August 2012 7 M9999-082912-A Micrel Inc. MIC23201 Functional Characteristics August 2012 8 M9999-082912-A Micrel Inc. MIC23201 Functional Characteristics (Continued) August 2012 9 M9999-082912-A Micrel Inc. MIC23201 Functional Characteristics (Continued) August 2012 10 M9999-082912-A Micrel Inc. MIC23201 Functional Diagram Figure 1. Simplified MIC23201 Functional Block Diagram voltage from overshooting at start up. Do not leave this pin floating. Functional Description VIN The input supply (VIN) provides power to the internal MOSFETs for the switch mode regulator along with the internal control circuitry. The VIN operating range is 2.7V to 5.5V so an input capacitor, with a minimum voltage rating of 6.3V, is recommended. Due to the high switching speed, 22µF bypass capacitor placed close to VIN and the power ground (PGND) pin is required. Refer to the layout recommendations for details. SVIN The input supply (SVIN) provides power to internal control circuitry. This pin is connected externally to the VIN pin. A 2.2µF ceramic capacitor from the SVIN pin to AGND must be placed next to the IC. SW The switch (SW) connects directly to one end of the inductor and provides the current path during switching cycles. The other end of the inductor is connected to the load, SNS pin and output capacitor. Due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes whenever possible. SS The soft start (SS) pin is used to control the output voltage ramp up time. The approximate equation for the ramp time in seconds is 270x103 x ln(10) x CSS. For example, for a CSS = 470pF, Trise ~ 300µs. See the Typical Characteristics curve for a graphical guide. The minimum recommended value for CSS is 100pF. EN A logic high signal on the enable pin activates the output voltage of the device. A logic low signal on the enable pin deactivates the output and reduces supply current to 0.01µA. MIC23201 features built-in soft-start circuitry that reduces in-rush current and prevents the output August 2012 SNS The sense (SNS) pin is connected to the output of the device to provide feedback to the control circuitry. The 11 M9999-082912-A Micrel Inc. MIC23201 the internal 0.62V reference within the regulation loop. The output voltage can be programmed using the following equation: SNS connection should be placed close to the output capacitor. Refer to the layout recommendations for more details. AGND The analog ground (AGND) is the ground path for the biasing and control circuitry. The current loop for the signal ground should be separate from the power ground (PGND) loop. Refer to the layout recommendations for more details. R1 VOUT VREF 1 R2 where: R1 is the top resistor, R2 is the bottom resistor. The output voltage can be adjusted from 0.95V to 3.6V. PGND The power ground pin is the ground path for the high current. The current loop for the power ground should be as small as possible and separate from the analog ground (AGND) loop as applicable. Refer to the layout recommendations for more details. FB The FB pin is regulated to 0.62V. A resistor divider connecting the feedback to the output is used to adjust the desired output voltage. A resistor divider network is connected to this pin from the output and is compared to August 2012 PG The power good (PG) pin is an open drain output which indicates logic high when the output voltage is typically above 87% of its steady state voltage. A pull-up resistor of more than 5kΩ should be connected from PG to VOUT. 12 M9999-082912-A Micrel Inc. MIC23201 1 VOUT /VIN I PEAK IOUT VOUT 2 f L Application Information The MIC23201 is a high performance DC/DC step down regulator offering a small solution size. Supporting an output current up to 2A inside a tiny 3mm x 3mm MLF package and requiring only three external components, the MIC23201 is able to maintain high efficiency throughout the entire load range while providing ultrafast load transient response. The following sections provide additional device application information. As shown by the calculation above, the peak inductor current is inversely proportional to the switching frequency and the inductance; the lower the switching frequency or the inductance the higher the peak current. As input voltage increases, the peak current also increases. The size of the inductor depends on the requirements of the application. Refer to the Typical Application Circuit and Bill of Materials for details. DC resistance (DCR) is also important. While DCR is inversely proportional to size, DCR can represent a significant efficiency loss. Refer to the Efficiency Considerations. Input Capacitor A minimum of 4.7µF ceramic capacitor or greater should be placed close to the VIN pin and PGND / GND pin for bypassing but the recommended value of input capacitor is 22µF. A X5R or X7R temperature rating is recommended for the input capacitor. Y5V temperature rating capacitors, aside from losing most of their capacitance over temperature, can also become resistive at high frequencies. This reduces their ability to filter out high frequency noise. Compensation The MIC23201 is designed to be stable with a 1µH to 2.2µH inductor with a minimum of 4.7µF ceramic (X5R) output capacitor. Output Capacitor The MIC23201 was designed for use with a minimum of 4.7µF or greater ceramic output capacitor. Increasing the output capacitance will lower output ripple and improve load transient response but could increase solution size or cost. The recommended value of output capacitor is 22µF. A low equivalent series resistance (ESR) ceramic output capacitor is recommended based upon performance, size and cost. Both the X7R or X5R temperature rating capacitors are recommended. The Y5V and Z5U temperature rating capacitors are not recommended due to their wide variation in capacitance over temperature and increased resistance at high frequencies. Inductor Selection When selecting an inductor, it is important to consider the following factors (not necessarily in the order of importance): Inductance Rated current value Size requirements DC resistance (DCR) The MIC23201 was designed for use with a 1µH to 2.2µH inductor. For faster transient response, a 1µH inductor will yield the best result. For lower output ripple, a 2.2µH inductor is recommended. Maximum current ratings of the inductor are generally given in two methods; permissible DC current and saturation current. Permissible DC current can be rated either for a 40°C temperature rise or a 10% to 20% loss in inductance. Ensure the inductor selected can handle the maximum operating current. When saturation current is specified, make sure that there is enough margin so that the peak current does not cause the inductor to saturate. Peak current can be calculated as follows: August 2012 13 M9999-082912-A Micrel Inc. MIC23201 where: Efficiency Considerations Efficiency is defined as the amount of useful output power, divided by the amount of power supplied. V I Efficiency % OUT OUT VIN IIN PDISS is the power dissipated within the MLF package. θJA is a combination of junction-to-case thermal resistance (θJC) and Case-to-Ambient thermal resistance (θCA), since thermal resistance of the solder connection from the EPAD to the PCB is negligible, so θJA = θJC + θCA. TAMB is the operating ambient temperature. 100 Maintaining high efficiency serves two purposes. It reduces power dissipation in the power supply, reducing the need for heat sinks and thermal design considerations and it reduces consumption of current for battery powered applications. Reduced current draw from a battery increases the devices operating time and is critical in hand held devices. There are two types of losses in switching converters; DC losses and switching losses. DC losses are simply the power dissipation of I2R. Power is dissipated in the high side switch during the on cycle. Power loss is equal to the high side MOSFET RDSON multiplied by the RMS Switch Current squared. During the off cycle, the low side N-channel MOSFET conducts, also dissipating power. Device operating current also reduces efficiency. The product of the quiescent (operating) current and the supply voltage represents another DC loss. The current required driving the gates on and off at a constant 2MHz frequency and the switching transitions make up the switching losses. All but the inductor losses are inherent to the device. In which case, inductor selection becomes increasingly critical in efficiency calculations. As the inductors are reduced in size, the DC resistance (DCR) can become quite significant. The DCR losses can be calculated as follows: Thermal Measurements Measuring the IC’s case temperature is recommended to ensure it is within its operating limits. Although this might seem like a very elementary task, it is easy to get erroneous results. The most common mistake is to use the standard thermal couple that comes with a thermal meter. This thermal couple wire gauge is large, typically 22 gauge, and behaves like a heatsink, resulting in a lower case measurement. Two methods of temperature measurement are using a smaller thermal couple wire or an infrared thermometer. If a thermal couple wire is used, it must be constructed of 36 gauge wire or higher then (smaller wire size) to minimize the wire heat-sinking effect. In addition, the thermal couple tip must be covered in either thermal grease or thermal glue to make sure that the thermal couple junction is making good contact with the case of the IC. Omega brand thermal couple (5SC-TT-K-36-36) is adequate for most applications. Wherever possible, an infrared thermometer is recommended. The measurement spot size of most infrared thermometers is too large for an accurate reading on a small form factor ICs. However, an IR thermometer from Optris has a 1mm spot size, which makes it a good choice for measuring the hottest point on the case. An optional stand makes it easy to hold the beam on the IC for long periods of time. PDCR = IOUT2 x DCR From that, the loss in efficiency due to inductor resistance can be calculated as follows: VOUT IOUT Efficiency Loss 1 VOUT IOUT PDCR 100 Efficiency loss due to DCR is minimal at light loads and gains significance as the load is increased. Inductor selection becomes a trade-off between efficiency and size in this case. Thermal Considerations The MIC23201 is provided in a 3mm x 3mm MLF package – a package that has very good thermalperformance This package maximizes heat transfer from the junction to the exposed pad (EP), which connects to the ground plane. The size of the ground plane attached to the exposed pad determines the overall thermal resistance from the junction to the ambient air surrounding the printed circuit board. The junction temperature for a given ambient temperature can be calculated using: TJ = TAMB + PDISS JA August 2012 14 M9999-082912-A Micrel Inc. MIC23201 (FB) pin. PCB Layout Guidelines Warning!!! To minimize EMI and output noise, follow these layout recommendations. PCB Layout is critical to achieve reliable, stable and efficient performance. A ground plane is required to control EMI and minimize the inductance in power, signal and return paths. Thickness of the copper planes is also important in terms of dissipating heat. The 2 ounce copper thickness is adequate from thermal point of view and also thick copper plain helps in terms of noise immunity. Keep in mind thinner planes can be easily penetrated by noise The inductor can be placed on the opposite side of the PCB with respect to the IC. It does not matter whether the IC or inductor is on the top or bottom as long as there is enough air flow to keep the power components within their temperature limits. The input and output capacitors must be placed on the same side of the board as the IC. Output Capacitor The following guidelines should be followed to insure proper operation of the MIC23201 converter. Use a wide trace to connect the output capacitor ground terminal to the input capacitor ground terminal. Phase margin will change as the output capacitor value and ESR changes. Contact the factory if the output capacitor is different from what is shown in the BOM. IC Place the IC close to the point of load (POL). Use fat traces to route the input and output power lines. The signal ground pin (AGND) must be connected directly to the ground planes. Signal and power grounds should be kept separate and connected at only one location. To minimize noise, place a ground plane underneath the inductor. The feedback trace should be separate from the power trace and connected as close as possible to the output capacitor. Sensing a long high current load trace can degrade the DC load regulation. RC Snubber Place the RC snubber on either side of the board and as close to the SW pin as possible. Input Capacitor Place the input capacitor next to the power pins. Place the input capacitors on the same side of the board and as close to the IC as possible. Keep both the VIN pin and PGND connections short. Place several vias to the ground plane close to the input capacitor ground terminal. Use either X7R or X5R dielectric input capacitors. Do not use Y5V or Z5U type capacitors. Do not replace the ceramic input capacitor with any other type of capacitor. Any type of capacitor can be placed in parallel with the input capacitor. If a Tantalum input capacitor is placed in parallel with the input capacitor, it must be recommended for switching regulator applications and the operating voltage must be derated by 50%. In “Hot-Plug” applications, a Tantalum or Electrolytic bypass capacitor must be used to limit the overvoltage spike seen on the input supply with power is suddenly applied. Inductor Keep the inductor connection to the switch node (SW) short. Do not route any digital lines underneath or close to the inductor. Keep the switch node (SW) away from the feedback August 2012 15 M9999-082912-A Micrel Inc. MIC23201 Typical Application Circuit Bill of Materials Item C1, C2 C3 Part Number Manufacturer GRM31CR71A226KE15L Murata AVX GRM188R71H471KA01D Murata C1608X7R1H471K TDK VLS4012T-1R0N1R6 CRCW0201301KFKED R2 ERJ-1GEF1583C R3, R4 CRCW020110K0JNED R5 ERJ-3GEYJ2R2V R6 CRCW020149R9FKED U1 MIC23201YML Ceramic Capacitor, 470pF, 50V, X7R, Size 0603 1 Not Fitted (NF) 1 Ceramic Capacitor, 2.2µ F, 6.3V, X5R, Size 0603 Murata C1608X5R0J225K R1 2 AVX GRM188R60J225KE19D L1 Ceramic Capacitor, 22µF, 10V, X7R, Size 1206 (3) 06036D225KAT2A C5 Qty. (2) 06035C471KAT2A C4 Description (1) TDK TDK Vishay/Dale(4) Panasonic - ECG (5) Vishay/Dale 1µH, 2.5A, 60mΩ, L4.0mm x W4.0mm x H1.2mm 1 Resistor, 301k Ω, Size 0603 1 Resistor,158k Ω, Size 0603 1 Resistor,10k Ω, Size 0603 2 Panasonic - ECG Resistor, 2.2 Ω, Size 0603 Vishay/Dale Resistor, 49.9Ω, Size 0603 Micrel, Inc.(6) 2MHz 2A Buck Regulator with Hyper Speed Control Mode 1 Notes: 1. Murata : www.murata.com. 2. AVX: www.avx.com. 3. TDK: www.tdk.com. 4. Vishay: www.vishay.com. 5. Panasonic: www.industrial.panasonic.com. 6. Micrel, Inc.: www.micrel.com. August 2012 16 M9999-082912-A Micrel Inc. MIC23201 PCB Layout Figure 11. MIC23201 Evaluation Board Top Layer Figure 12. MIC23201 Evaluation Board Mid-Layer 1 (Ground Plane) August 2012 17 M9999-082912-A Micrel Inc. MIC23201 PCB Layout (Continued) Figure 13. MIC23201 Evaluation Board Mid-Layer 2 Figure 14. MIC23201 Evaluation Board Bottom Layer August 2012 18 M9999-082912-A Micrel Inc. MIC23201 Recommended Land Pattern ALL UNITS ARE IN mm, TOLERANCE 0.05, IF NOT NOTED LP # MLF33D-10LD-LP-1 August 2012 19 M9999-082912-A Micrel Inc. MIC23201 Package Information 10-Pin 3mm x 3mm MLF (ML) 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. © 2012 Micrel, Incorporated. August 2012 20 M9999-082912-A