MIC23150 4MHz PWM 2A Buck Regulator with HyperLight Load™ General Description Features The MIC23150 is a high efficiency 4MHz 2A synchronous buck regulator with HyperLight Load™ mode. HyperLight Load™ provides very high efficiency at light loads and 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 2mm x 2mm Thin MLF® package saves precious board space and requires only three external components. The MIC23150 is designed for use with a very small inductor, down to 0.47µH, and an output capacitor as small as 2.2 µF that enables a total solution size, less than 1mm height. The MIC23150 has a very low quiescent current of 23µA and achieves a peak efficiency of 93% in continuous conduction mode. In discontinuous conduction mode, the MIC23150 can achieve 87% efficiency at 1mA. The MIC23150 is available in 8-pin 2mm x 2mm Thin MLF® package with an operating junction temperature range from –40°C to +125°C. Datasheets and support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • • • • • • • • HyperLight Load™ Input voltage: 2.7V to 5.5V 2A output current Up to 93% peak efficiency 87% typical efficiency at 1mA 23µA typical quiescent current 4MHz PWM operation in continuous mode Ultra fast transient response Low ripple output voltage − 14mVpp ripple in HyperLight Load™ mode − 5mV output voltage ripple in full PWM mode Fully integrated MOSFET switches 0.01µA shutdown current Thermal shutdown and current limit protection Output Voltage as low as 0.95V 8-pin 2mm x 2mm Thin MLF® –40°C to +125°C junction temperature range Applications • Mobile handsets • Portable media/MP3 players • Portable navigation devices (GPS) • WiFi/WiMax/WiBro modules • Solid State Drives/Memory • Wireless LAN cards • Portable applications ____________________________________________________________________________________________________________ Typical Application U1 MIC23150 L1 VIN VIN C1 EN SW 2mm×2mm ThinMLF SNS VOUT 100 Efficiency V = 1.8V OUT VIN = 2.7V V = 3.0V IN V = 3.6V IN 90 C2 80 70 EN 60 AGND PGND GND 50 GND 40 11 L = 1.0µH C = 4.7µF OUT 0 100 1000 10000 OUTPUT CURRENT (mA) HyperLight Load 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 February 2009 M9999-082908-A Micrel Inc. MIC23150 Ordering Information Part Number Marking Code Nominal Output Voltage Junction Temp. Range Package Lead Finish MIC23150-CYMT QKC 1.0V -40°C to +125°C 8-Pin 2mm x 2mm Thin MLF® Pb-Free MIC23150-4YMT QK4 1.2V -40°C to +125°C 8-Pin 2mm x 2mm Thin MLF® Pb-Free 8-Pin 2mm x 2mm Thin MLF ® Pb-Free 8-Pin 2mm x 2mm Thin MLF ® Pb-Free MIC23150-GYMT MIC23150-SYMT QKG 1.8V QKS 3.3V –40°C to +125°C –40°C to +125°C Notes: 1. Other options available (0.95V - 3.6V). Contact Micrel Marketing for details. ® 2. Thin MLF is GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. ® 3. Thin MLF ▲ = Pin 1 identifier. Pin Configuration SW 1 8 PGND SW 2 7 VIN EN 3 6 VIN SNS 4 5 AGND (Top View) 2mm x 2mm Thin MLF (MT) Pin Description Pin Number Pin Name 1,2 SW Switch (Output): Internal power MOSFET output switches. 3 EN Enable (Input): Logic high enables operation of the regulator. Logic low will shut down the device. Do not leave floating. 4 SNS 5 AGND February 2009 6,7 VIN 8 PGND Pin Function Sense: Connect to VOUT as close to output capacitor as possible to sense output voltage. Analog Ground: Connect to central ground point where all high current paths meet (CIN, COUT, PGND) for best operation. Input Voltage: Connect a capacitor-to-ground to decouple the noise. Power Ground. 2 M9999-082908-A Micrel Inc. MIC23150 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) . ……………………………………….6V Sense (VSNS).. ..................................................................6V Output Switch Voltage (VSW) ............................................6V Enable Input Voltage (VEN).. ..............................-0.3V to VIN Storage Temperature Range .. ……………-65°C to +150°C ESD Rating(3) ..................................................................2kV Supply Voltage (VIN)... …………………………..2.7V to 5.5V Enable Input Voltage (VEN) .. ……………………….0V to VIN Junction Temperature Range (TJ)... ….-40°C ≤ TJ ≤ +125°C Thermal Resistance 2mm x 2mm Thin MLF-8 (θJA) ...........................90°C/W Electrical Characteristics(4) TA = 25°C; VIN = VEN = 3.6V; L = 1.0µH; COUT = 4.7µF unless otherwise specified. Bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted. Parameter Condition Min Supply Voltage Range Under-Voltage Lockout Threshold 2.7 (turn-on) 2.45 Under-Voltage Lockout Hysteresis IOUT = 0mA , SNS > 1.2 * VOUT Nominal Shutdown Current VEN = 0V; VIN = 5.5V VIN = 3.6V if VOUTNOM < 2.5V, ILOAD = 20mA VIN = 4.5V if VOUTNOM ≥ 2.5V, ILOAD = 20mA Current Limit SNS = 0.9*VOUTNOM Output Voltage Line Regulation 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 Output Voltage Load Regulation PWM Switch ON-Resistance 2.55 Max Units 5.5 V 2.65 75 Quiescent Current Output Voltage Accuracy Typ 23 40 µA 0.01 5 µA +2.5 % -2.5 2.2 3.4 A 0.3 %/V 0.75 %/A ISW = 100mA PMOS 0.150 ISW = -100mA NMOS 0.110 Switching Frequency IOUT = 120mA SoftStart Time VOUT = 90% Enable Threshold Turn-On V mV Ω 4 MHz 115 µs 0.8 1.2 V Enable Input Current 0.1 2 µA Over-temperature Shutdown 160 °C Over-temperature Shutdown Hysteresis 20 °C 0.5 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. February 2009 3 M9999-082908-A Micrel Inc. MIC23150 Typical Characteristics OUT February 2009 OUTPUT VOLTAGE (V) 1.81 1.80 1.79 1.78 L =1.0µH 1.77 C = 4.7µF OUT 1.76 LOAD = 120mA 1.75 TEMPERATURE (°C) 4 3.2 3.7 4.2 4.7 5.2 INPUT VOLTAGE (V) 5.7 Output Voltage vs Output Current V = 5.5V IN 1.86 V = 4.2V V = 3.6V 1.84 IN IN 1.82 1.8 1.78 V IN = 2.7V 1.76 L = 1.0µH 1.74 V = 1.8V OUT 1.72 C = 4.7µF OUT 1.7 0.1 1 10 100 1000 10000 OUTPUT CURRENT (mA) Enable Thresold vs. Temperature 1.2 1.82 -20 120 1.6 2.7 Output Voltage vs. Temperature 1.83 -40 OUTPUT VOLTAGE (V) TEMPERATURE (°C) 100 80 60 40 20 0 -20 3.9 V = 3.6V 3.8 IN L =1.0µH 3.7 C = 4.7µF 3.6 OUT LOAD = 120mA 3.5 -40 SWITCHING FREQUENCY (MHz) 4.0 = 4.7µF 10 100 1000 10000 OUTPUT CURRENT (mA) 1.85 1.84 4.1 1.7 1.65 VIN = 2.7V ENABLE ON VIN = 3.6V 1.0 VIN = 5.5V 0.8 ENABLE OFF 0.6 0.4 L = 1.0µH 0.2 COUT = 4.7µF 0 120 C 4.5 4.4 4.2 = 4.2V L = 1.0µH = 1.8V V Switching Frequency vs. Temperature 4.3 = 3.6V OUT 0.001 1 1.75 Load = 1000mA Load = 1500mA 1.9 1.88 0.1 0.01 Load = 200mA Load = 600mA 80 IN 1.8 100 V Output Voltage vs. Input Voltage 60 5.7 IN = 1.8V 1 10 100 1000 10000 OUTPUT CURRENT (mA) 40 3.2 3.7 4.2 4.7 5.2 INPUT VOLTAGE (V) V OUT 0 1.6 2.7 IN = 3.6V COUT = 4.7µF 20 1.65 1 = 3.0V IN 1.9 1.85 ENABLE THRESHOLD (V) 1.7 V 120 Load = 1mA Load = 100mA 10 V 1.95 5.7 Switching Frequency vs Output Current 80 Load = 10mA 10 Not Switching L = open 5 = 1.2V × V V OUT NOM 0 2.7 3.2 3.7 4.2 4.7 5.2 INPUT VOLTAGE (V) 100 1.9 15 60 1.95 -40°C L = 2.2µH V -20 Output Voltage vs. Input Voltage 25°C 125°C 25 20 65 60 55 50 0.1 OUTPUT VOLTAGE (V) 5.7 30 L = 1.5µH 75 70 2 35 40 2.8 2.6 2.4 L = 1.0µH 2.2 C = 4.7µF OUT 2.0 2.7 3.2 3.7 4.2 4.7 5.2 INPUT VOLTAGE (V) = 5.5V Quiescent Current vs. Input Voltage 40 3.4 3.2 3.0 1.75 IN L = 1.0µH L = 0.68µH 90 85 80 -40 EFFICIENCY (%) Current Limit vs. Input Voltage 1.85 V 50 L = 1.0µH = 4.7µF C OUT 40 0.1 1 10 100 1000 10000 OUTPUT CURRENT (mA) 1 10 100 1000 10000 OUTPUT CURRENT (mA) 2 VIN = 5.0V 60 L = 1.0µH COUT = 4.7µF 4.0 3.8 3.6 1.8 70 QUIESCENT CURRENT (µA) CURRENT LIMIT (A) 40 0.1 80 0 50 OUTPUT VOLTAGE (V) VIN = 5.5V VIN = 5.0V SWITCHING FREQUENCY (MHz) EFFICIENCY (%) 70 Efficiency with Various Inductors 100 95 VIN = 4.2V 90 80 VIN = 4.2V OUT 100 VIN = 3.6V 90 60 Efficiency = 3.3V V 20 OUT 100 VIN = 3.0V VIN = 2.7V EFFICIENCY (%) Efficiency = 1.8V V TEMPERATURE (°C) M9999-082908-A Micrel Inc. MIC23150 Functional Characteristics February 2009 5 M9999-082908-A Micrel Inc. February 2009 MIC23150 6 M9999-082908-A Micrel Inc. MIC23150 Functional Characteristics (cont.) February 2009 7 M9999-082908-A Micrel Inc. MIC23150 Functional Characteristics (cont.) February 2009 8 M9999-082908-A Micrel Inc. MIC23150 Functional Diagram VIN EN CONTROL LOGIC Timer & Softstart UVLO Gate Drive Reference SW Current Limit ZERO 1 ERROR COMPARATOR ISENSE PGND SNS AGND Figure 1. Simplified MIC23150 Functional Block Diagram February 2009 9 M9999-082908-A Micrel Inc. MIC23150 Functional Description SNS The sense (SNS) pin is connected to the output of the device to provide feedback to the control circuitry. The SNS connection should be placed close to the output capacitor. Refer to the layout recommendations for more details. 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, a minimum 2.2µF bypass capacitor placed close to VIN and the power ground (PGND) pin is required. Refer to the layout recommendations for 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. 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. MIC23150 features built-in soft-start circuitry that reduces in-rush current and prevents the output voltage from overshooting at start up. Do not leave the EN pin floating. PGND The power ground pin is the ground path for the high current in PWM mode. 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. 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. February 2009 10 M9999-082908-A Micrel Inc. MIC23150 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: Application Information The MIC23150 is a high performance DC-to-DC step down regulator offering a small solution size. Supporting an output current up to 2A inside a tiny 2mm x 2mm Thin MLF® package, the IC requires only three external components while meeting today’s miniature portable electronic device needs. Using the HyperLight Load™ switching scheme, the MIC23150 is able to maintain high efficiency throughout the entire load range while providing ultra-fast load transient response. The following sections provide additional device application information. ⎡ ⎛ 1 − VOUT /VIN ⎞⎤ I PEAK = ⎢IOUT + VOUT ⎜ ⎟⎥ ⎝ 2 × f × L ⎠⎦ ⎣ 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 2.2µF ceramic capacitor or greater should be placed close to the VIN pin and PGND pin for bypassing. A TDK C1608X5R0J475K, size 0603, 4.7µF ceramic capacitor is recommended based upon performance, size and cost. 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 MIC23150 is designed to be stable with a 0.47µH to 2.2µH inductor with a minimum of 2.2µF ceramic (X5R) output capacitor. Output Capacitor The MIC23150 is designed for use with a 2.2µF or greater ceramic output capacitor. Increasing the output capacitance will lower output ripple and improve load transient response but could also increase solution size or cost. A low equivalent series resistance (ESR) ceramic output capacitor such as the TDK C1608X5R0J475K, size 0603, 4.7µF ceramic 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. Duty Cycle The typical maximum duty cycle of the MIC23150 is 80%. 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 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 Switch Current squared. During the off cycle, the low side Nchannel 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 4MHz frequency and the switching transitions make up the switching losses. 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 MIC23150 is designed for use with a 0.47µH to 2.2µH inductor. For faster transient response, a 0.47µH 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 February 2009 ⎞ ⎟ × 100 ⎟ ⎠ 11 M9999-082908-A Micrel Inc. MIC23150 100 EFFICIENCY (%) 90 the error comparator turns the PMOS off for a minimumoff-time until the output drops below the threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using a 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 MIC23150 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases, thus provides more energy to the output. This switching scheme improves the efficiency of MIC23150 during light load currents by only switching when it is needed. As the load current increases, the MIC23150 goes into continuous conduction mode (CCM) and switches at a frequency centered at 4MHz. The equation to calculate the load when the MIC23150 goes into continuous conduction mode may be approximated by the following formula: Efficiency = 1.8V V VIN = 2.7V OUT VIN = 3.0V VIN = 3.6V 80 70 60 50 40 0.1 VIN = 4.2V VIN = 5.0V VIN = 5.5V L = 1.0µH COUT = 4.7µF 1 10 100 1000 10000 OUTPUT CURRENT (mA) Figure 2. Efficiency Under Load The figure above shows an efficiency curve. From no load to 100mA, efficiency losses are dominated by quiescent current losses, gate drive and transition losses. By using the HyperLight Load™ mode, the MIC23150 is able to maintain high efficiency at low output currents. Over 100mA, efficiency loss is dominated by MOSFET RDSON and inductor losses. Higher input supply voltages will increase the Gate-to-Source threshold on the internal MOSFETs, thereby reducing the internal RDSON. This improves efficiency by reducing DC losses in the device. 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: ⎛ (V − VOUT ) × D ⎞ I LOAD > ⎜⎜ IN ⎟⎟ 2L × f ⎝ ⎠ As shown in the previous equation, the load at which MIC23150 transitions from HyperLight Load™ mode to PWM mode is a function of the input voltage (VIN), output voltage (VOUT), duty cycle (D), inductance (L) and frequency (f). As shown in Figure 3, as the Output Current increases, the switching frequency also increases until the MIC23150 goes from HyperLight LoadTM mode to PWM mode at approximately 120mA. The MIC23150 will switch at a relatively constant frequency around 4MHz once the output current is over 120mA. PDCR = IOUT2 x DCR From that, the loss in efficiency due to inductor resistance can be calculated as follows: 10 ⎞⎤ ⎟⎥ × 100 ⎟ ⎠⎦⎥ SW FREQUENCY (MHz) ⎡ ⎛ VOUT × IOUT Efficiency Loss = ⎢1 − ⎜⎜ V ⎣⎢ ⎝ OUT × IOUT + PDCR 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. V 1 IN = 3.0V V IN V IN = 3.6V = 4.2V 0.1 0.01 L = 4.7µH VOUT = 1.8V C HyperLight Load™ Mode MIC23150 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 February 2009 SW Frequency vs Output Current 0.001 1 OUT = 4.7µF 10 100 1000 10000 OUTPUT CURRENT (mA) Figure 3. SW Frequency vs. Output Current 12 M9999-082908-A Micrel Inc. MIC23150 MIC23150 Typical Application Circuit U1 MIC23150 L1 VIN VIN C1 EN SW 2mm×2mm ThinMLF SNS VOUT C2 EN AGND PGND GND GND Bill of Materials Item Part Number C1, C2 C1608X5R0J475K VLS3010T-1R0N1R9 L1 VLS4012T-1R0N1R6 DO2010-102ML U1 MIC23150-xYMT Manufacturer TDK(1) TDK (1) TDK (1) Coilcraft Description Qty. 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2 1µH, 1.9A, 60mΩ, L3.0mm x W3.0mm x H1.0mm 1 1µH, 2.8A, 50mΩ, L4.0mm x W4.0mm x H1.2mm (2) Micrel, Inc.(3) 1µH, 1.8A, 162mΩ, L2.0mm x W2.0mm x H1.0mm 4MHz 2A Buck Regulator with HyperLight Load™ Mode 1 Notes: 1. TDK: www.tdk.com 2. Coilcraft: www.coilcraft.com 3. Micrel, Inc.: www.micrel.com February 2009 13 M9999-082908-A Micrel Inc. MIC23150 PCB Layout Recommendations Thin MILF Top Layer Thin MLF Bottom Layer February 2009 14 M9999-082908-A Micrel Inc. MIC23150 Package Information 8-Pin 2mm x 2mm Thin MLF 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. February 2009 15 © 2008 Micrel, Incorporated. M9999-082908-A