Micrel, Inc. MIC5219 MIC5219 500mA-Peak Output LDO Regulator General Description Features The MIC5219 is an efficient linear voltage regulator with high peak output current capability, very-low-dropout voltage, and better than 1% output voltage accuracy. Dropout is typically 10mV at light loads and less than 500mV at full load. • 500mA output current capability SOT-23-5 package - 500mA peak 2mm×2mm MLF® package - 500mA continuous 2mm×2mm Thin MLF® package - 500mA continuous MSOP-8 package - 500mA continuous • Low 500mV maximum dropout voltage at full load • Extremely tight load and line regulation • Tiny SOT-23-5 and MM8™ power MSOP-8 package • Ultra-low-noise output • Low temperature coefficient • Current and thermal limiting • Reversed-battery protection • CMOS/TTL-compatible enable/shutdown control • Near-zero shutdown current The MIC5219 is designed to provide a peak output current for start-up conditions where higher inrush current is demanded. It features a 500mA peak output rating. Continuous output current is limited only by package and layout. The MIC5219 can be enabled or shut down by a CMOS or TTL compatible signal. When disabled, power consumption drops nearly to zero. Dropout ground current is minimized to help prolong battery life. Other key features include reversedbattery protection, current limiting, overtemperature shutdown, and low noise performance with an ultra-low-noise option. The MIC5219 is available in adjustable or fixed output voltages in the space-saving 6-pin (2mm × 2mm) MLF®, 6-pin (2mm × 2mm) Thin MLF® SOT‑23‑5 and MM8® 8‑pin power MSOP packages. For higher power requirements see the MIC5209 or MIC5237. Applications • • • • • • All support documentation can be found on Micrel’s web site at www.micrel.com. Laptop, notebook, and palmtop computers Cellular telephones and battery-powered equipment Consumer and personal electronics PC Card VCC and VPP regulation and switching SMPS post-regulator/DC-to-DC modules High-efficiency linear power supplies Typical Applications MIC5219-5.0BMM ENABLE SH U TD OWN VIN 6V VOUT5V 2.2µF tantalum 1 8 2 7 3 6 4 5 MIC5219-3.3BM5 VIN 4V ENABLE SH U TD OWN ENABLE SHUTDOWN EN 5 VOUT3.3V 2.2µF tantalum 2 4 3 470pF 470pF 5V Ultra-Low-Noise Regulator VIN 1 VOUT MIC5219-x.xYML 1 6 2 5 3 4 3.3V Ultra-Low-Noise Regulator CBYP VIN ENABLE SHUTDOWN COUT (optional) EN VOUT MIC5219YMT 1 6 2 5 3 4 R1 470pF + 2.2µF R2 Ultra-Low-Noise Regulator (Adjustable) Ultra-Low-Noise Regulator (Fixed) MM8 is a registered trademark of Micrel, Inc. MicroLeadFrame and MLF are registered trademarks of 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 June 2009 1 M0371-061809 Micrel, Inc. MIC5219 Ordering Information Part Number Standard Pb-Free MIC5219-2.5BMM MIC5219-2.5YMM Marking Standard Pb-Free* Volts Temp. Range Package — — 2.5V –40°C to +125°C MSOP-8 MIC5219-2.85BMM MIC5219-2.85YMM — — 2.85V –40°C to +125°C MSOP-8 MIC5219-3.0BMM MIC5219-3.0YMM — — 3.0V –40°C to +125°C MSOP-8 MIC5219-3.3BMM MIC5219-3.3YMM — — 3.3V –40°C to +125°C MSOP-8 MIC5219-3.6BMM MIC5219-3.6YMM — — 3.6V –40°C to +125°C MSOP-8 MIC5219-5.0BMM MIC5219-5.0YMM — — 5.0V –40°C to +125°C MSOP-8 MIC5219BMM MIC5219YMM — — Adj. –40°C to +125°C MSOP-8 MIC5219-2.5BM5 MIC5219-2.5YM5 LG25 LG25 2.5V –40°C to +125°C SOT-23-5 MIC5219-2.6BM5 MIC5219-2.6YM5 LG26 LG26 2.6V –40°C to +125°C SOT-23-5 MIC5219-2.7BM5 MIC5219-2.7YM5 LG27 LG27 2.7V –40°C to +125°C SOT-23-5 MIC5219-2.8BM5 MIC5219-2.8YM5 LG28 LG28 2.8V –40°C to +125°C SOT-23-5 MIC5219-2.8BML MIC5219-2.8YML G28 G28 2.8V –40°C to +125°C 6-Pin 2×2 MLF® MIC5219-2.85BM5 MIC5219-2.85YM5 LG2J LG2J 2.85V –40°C to +125°C SOT-23-5 MIC5219-2.9BM5 MIC5219-2.9YM5 LG29 LG29 2.9V –40°C to +125°C SOT-23-5 MIC5219-3.1BM5 MIC5219-3.1YM5 LG31 LG31 3.1V –40°C to +125°C SOT-23-5 MIC5219-3.0BM5 MIC5219-3.0YM5 LG30 LG30 3.0V –40°C to +125°C SOT-23-5 MIC5219-3.0BML MIC5219-3.0YML G30 G30 3.0V –40°C to +125°C 6-Pin 2×2 MLF® MIC5219-3.3BM5 MIC5219-3.3YM5 LG33 LG33 3.3V –40°C to +125°C SOT-23-5 MIC5219-3.3BML MIC5219-3.3YML G33 G33 3.3V –40°C to +125°C 6-Pin 2×2 MLF® MIC5219-3.6BM5 MIC5219-3.6YM5 LG36 LG36 3.6V –40°C to +125°C SOT-23-5 MIC5219-5.0BM5 MIC5219-5.0YM5 LG50 LG50 5.0V –40°C to +125°C SOT-23-5 LGAA SOT-23-5 MIC5219BM5 MIC5219YM5 LGAA Adj. –40°C to +125°C MIC5219YMT GAA Adj. –40°C to +125°C 6-Pin 2x2 Thin MLF®** MIC5219-5.0YMT G50 5.0V –40°C to +125°C 6-Pin 2x2 Thin MLF®** Other voltages available. Consult Micrel for details. * Over/underbar may not be to scale. ** Pin 1 identifier = ▲. Pin Configuration EN 1 8 GND IN 2 7 GND EN 1 OUT 3 6 GND GND 2 BYP 4 5 GND IN 3 MIC5219-x.xBMM / MM8® / MSOP-8 Fixed Voltages (Top View) E N GND IN 6 BYP 4 OUT MIC5219-x.xBML 6-Pin 2mm × 2mm MLF® (ML) (Top View) 8 GND IN 2 7 GND EN 1 OUT 3 6 GND GND 2 5 ADJ BYP 4 5 GND IN 3 4 OUT June 2009 2 1 L Gx x 5 NC EN 1 MIC5219YMM / MIC5219BMM MM8® MSOP-8 Adjustable Voltage (Top View) 3 4 5 BYP OUT MIC5219-x.xBM5 / SOT-23-5 Fixed Voltages (Top View) E N GND IN 6 NC MIC5219YMT 6-Pin 2mm × 2mm Thin MLF® (MT) (Top View) 2 3 2 1 LGAA 4 5 ADJ OUT Part Identification MIC5219BM5 / SOT-23-5 Adjustable Voltage (Top View) M0371-061809 Micrel, Inc. MIC5219 Pin Description Pin No. MLF-6 TMLF-6 Pin No. MSOP-8 Pin No. SOT-23-5 Pin Name Pin Function 3 2 1 IN Supply Input. 2 5–8 2 GND Ground: MSOP-8 pins 5 through 8 are internally connected. 4 3 5 OUT Regulator Output. 1 1 3 EN Enable (Input): CMOS compatible control input. Logic high = enable; logic low or open = shutdown. 6 4 (fixed) 4 (fixed) BYP Reference Bypass: Connect external 470pF capacitor to GND to reduce output noise. May be left open. 5(NC) 4 (adj.) 4 (adj.) ADJ Adjust (Input): Feedback input. Connect to resistive voltage-divider network. EP — — GND Ground: Internally connected to the exposed pad. Connect externally to GND pin. June 2009 3 M0371-061809 Micrel, Inc. MIC5219 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Input Voltage (VIN)...............................–20V to +20V Power Dissipation (PD).............................. Internally Limited Junction Temperature (TJ)......................... –40°C to +125°C Storage Temperature (TS)......................... –65°C to +150°C Lead Temperature (Soldering, 5 sec.)........................ 260°C Supply Input Voltage (VIN)............................. +2.5V to +12V Enable Input Voltage (VEN)....................................0V to VIN Junction Temperature (TJ)......................... –40°C to +125°C Package Thermal Resistance............................ see Table 1 Electrical Characteristics(3) VIN = VOUT + 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted. Symbol Parameter Conditions Min Output Voltage Accuracy variation from nominal VOUT VOUT ΔVOUT/ΔT ppm/°C Output Voltage Note 4 Typical –1 –2 40 Max Units 1 2 % % Temperature Coefficient ΔVOUT/VOUT Line Regulation VIN = VOUT + 1V to 12V 0.009 0.05 0.1 %/V IOUT = 100µA to 500mA, Note 5 0.05 ΔVOUT/VOUT Load Regulation 0.5 0.7 % Dropout Voltage(6) IOUT = 100µA 10 VIN – VOUT 60 80 mV 115 IOUT = 50mA 175 250 mV 175 IOUT = 150mA 300 400 mV 350 IOUT = 500mA 500 600 mV Ground Pin Current(7, 8) VEN ≥ 3.0V, IOUT = 100µA 80 IGND 130 170 µA 350 VEN ≥ 3.0V, IOUT = 50mA 650 900 µA 1.8 VEN ≥ 3.0V, IOUT = 150mA 2.5 3.0 mA 12 VEN ≥ 3.0V, IOUT = 500mA 20 25 mA Ground Pin Quiescent Current(8) PSRR Ripple Rejection ILIMIT Current Limit eno Output Noise(10) ΔVOUT/ΔPD Thermal Regulation ENABLE Input VEN ≤ 0.4V 0.05 3 µA VEN ≤ 0.18V 0.10 8 µA f = 120Hz 75 VOUT = 0V 700 IENL Enable Input Current Note 9 0.05 500 nV/ Hz 300 nV/ Hz IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF VEN = logic high (regulator enabled) VENL ≤ 0.18V 4 0.4 0.18 2.0 VENL ≤ 0.4V %/W V V 0.01 –1 µA 0.01 –2 µA 20 25 µA VENH ≥ 2.0V 2 5 IENH June 2009 dB mA IOUT = 50mA, COUT = 2.2µF, CBYP = 0 Enable Input Logic-Low Voltage VEN = logic low (regulator shutdown) VENL 1000 M0371-061809 Micrel, Inc. MIC5219 Notes: 1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max), the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: PD(max) = (TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. See Table 1 and the “Thermal Considerations” section for details. 2. The device is not guaranteed to function outside its operating rating. 3. Specification for packaged product only. 4. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. 5. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 100µA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 6. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential. 7. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of the load current plus the ground pin current. 8. VEN is the voltage externally applied to devices with the EN (enable) input pin. 9. Thermal regulation is defined as the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 500mA load pulse at VIN = 12V for t = 10ms. 10. CBYP is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin. June 2009 5 M0371-061809 Micrel, Inc. MIC5219 Typical Characteristics Power Supply Rejection Ratio 0 0 V IN = 6V V OUT = 5V -20 Power Supply Rejection Ratio 0 V IN = 6V V OUT = 5V -20 -40 -40 -60 -60 -60 -80 IOUT = 100µA C OUT = 1µF -100 1k 1E+4 10k 1E+5 1M 1E+7 10M 10 1E+2 100 1E+3 100k 1E+6 1E+1 FREQUENCY (Hz) Power Supply Rejection Ratio Power Supply Rejection Ratio 0 V IN = 6V V OUT = 5V -20 -40 -40 -60 -60 -100 1k 1E+4 10k 1E+5 1M 1E+7 10M 10 1E+2 100 1E+3 100k 1E+6 1E+1 FREQUENCY (Hz) Power Supply Ripple Rejection vs. Voltage Drop 60 V IN = 6V V OUT = 5V -20 IOUT = 100mA C OUT = 1µF -80 IOUT = 1mA C OUT = 1µF -100 1k 1E+4 10k 1E+5 1M 1E+7 10M 10 1E+2 100 1E+3 100k 1E+6 1E+1 FREQUENCY (Hz) 0 V IN = 6V V OUT = 5V -20 -40 -80 Power Supply Rejection Ratio 50 1mA 40 30 IOUT = 100µA C OUT = 2.2µF C BYP = 0.01µF -80 -100 1k 1E+4 10k 1E+5 1M 1E+7 10M 10 1E+2 100 1E+3 100k 1E+6 1E+1 FREQUENCY (Hz) Power Supply Ripple Rejection vs. Voltage Drop 100 90 80 70 60 50 40 30 20 10 0 10 -100 1k 1E+4 10k 1E+5 1M 1E+7 10M 10 1E+2 100 1E+3 100k 1E+6 1E+1 FREQUENCY (Hz) 10 Noise Performance 10mA, C 1 1mA OUT IOUT = 100mA 20 IOUT = 1mA C OUT = 2.2µF C BYP = 0.01µF -80 10mA 0 C OUT = 1µF 0 0.1 0.2 0.3 VOLTAGE DROP (V) 0.4 Noise Performance 10 = 1µF 1 0.1 0.1 0.01 0.01 0.001 0.001 100mA 10mA IOUT = 100mA 10mA C OUT = 2.2µF C BYP = 0.01µF 0 10 0.1 0.2 0.3 VOLTAGE DROP (V) 0.4 Noise Performance V OUT = 5V 0.0001 10 1E+2 1k 1E+4 1E+1 100 1E+3 10k 1E+5 100k 1E+6 1M 1E+7 10M FREQUENCY (Hz) 100mA Dropout Voltage vs. Output Current Dropout Characteristics 400 3.5 300 2.0 200 0.0001 1k 1E+4 10 1E+2 10k 1E+5 100k 1E+6 1M 1E+7 10M 1E+1 100 1E+3 FREQUENCY (Hz) June 2009 1.5 1mA 10mA I L =100µA 2.5 0.1 0.01 V OUT = 5V C OUT = 10µF 0.001 electrolytic C BYP = 100pF I =100mA L 1.0 100 I =500mA L 0.5 0 1mA 0.0001 1k 1E+4 10 1E+2 10k 1E+5 100k 1E+6 1M 1E+7 10M 100 1E+3 1E+1 FREQUENCY (Hz) 3.0 1 V OUT = 5V C OUT = 10µF electrolytic 0 100 200 300 400 OUTPUT CURRENT (mA) 6 500 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 M0371-061809 Micrel, Inc. MIC5219 Ground Current vs. Output Current Ground Current vs. Supply Voltage Ground Current vs. Supply Voltage 12 3.0 25 10 2.5 20 8 2.0 15 6 1.5 10 4 2 5 0 0 0 June 2009 100 200 300 400 OUTPUT CURRENT (mA) 500 IL =100 mA 1.0 0.5 IL =500mA 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 7 8 9 0 IL =100µA 0 2 4 6 INPUT VOLTAGE (V) 8 M0371-061809 Micrel, Inc. MIC5219 Block Diagrams VIN OUT IN VOU T COU T BYP CB Y P (optional) Bandgap Ref. V REF EN Current Limit Thermal Shutdown MIC5219-x.xBM5/M/YMT GND Ultra-Low-Noise Fixed Regulator VIN OUT IN VOU T R1 R2 Bandgap Ref. V REF COU T CB Y P (optional) EN Current Limit Thermal Shutdown MIC5219BM5/MM/YMT GND Ultra-Low-Noise Adjustable Regulator June 2009 8 M0371-061809 Micrel, Inc. MIC5219 Applications Information Thermal Considerations The MIC5219 is designed to provide 200mA of continuous current in two very small profile packages. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power dissipation of the package, use the thermal resistance, junction-to-ambient, of the device and the following basic equation. The MIC5219 is designed for 150mA to 200mA output current applications where a high current spike (500mA) is needed for short, start-up conditions. Basic application of the device will be discussed initially followed by a more detailed discussion of higher current applications. Enable/Shutdown Forcing EN (enable/shutdown) high (>2V) enables the regulator. EN is compatible with CMOS logic. If the enable/ shutdown feature is not required, connect EN to IN (supply input). See Figure 5. ( T (max ) − T ) J A θ JA TJ(max) is the maximum junction temperature of the die, 125°C, and TA is the ambient operating temperature. θJA is layout dependent; Table 1 shows examples of thermal resistance, junction-to-ambient, for the MIC5219. Input Capacitor A 1µF capacitor should be placed from IN to GND if there is more than 10 inches of wire between the input and the AC filter capacitor or if a battery is used as the input. Package Output Capacitor An output capacitor is required between OUT and GND to prevent oscillation. The minimum size of the output capacitor is dependent upon whether a reference bypass capacitor is used. 1µF minimum is recommended when CBYP is not used (see Figure 5). 2.2µF minimum is recommended when CBYP is 470pF (see Figure 6). For applications < 3V, the output capacitor should be increased to 22µF minimum to reduce start-up overshoot. Larger values improve the regulator’s transient response. The output capacitor value may be increased without limit. θJA Recommended θJA 1" Square Minimum Footprint 2oz. Copper θJC MM8® (MM) 160°C/W 70°C/W 30°C/W SOT-23-5 (M5) 220°C/W 170°C/W 130°C/W 2×2 MLF® (ML) 90°C/W — — 2×2 Thin MLF® (MT) 90°C/W — — Table 1. MIC5219 Thermal Resistance The actual power dissipation of the regulator circuit can be determined using one simple equation. The output capacitor should have an ESR (equivalent series resistance) of about 1Ω or less and a resonant frequency above 1MHz. Ultra-low-ESR capacitors could cause oscillation and/or underdamped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Many aluminum electrolytics have electrolytes that freeze at about –30°C, so solid tantalums are recommended for operation below –25°C. PD = (VIN – VOUT) IOUT + VIN IGND Substituting PD(max) for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. For example, if we are operating the MIC5219-3.3BM5 at room temperature, with a minimum footprint layout, we can determine the maximum input voltage for a set output current. At lower values of output current, less output capacitance is needed for stability. The capacitor can be reduced to 0.47µF for current below 10mA, or 0.33µF for currents below 1mA. No-Load Stability P D (max ) = (125 °C − 25°C ) 220°C / W PD(max) = 455mW The thermal resistance, junction-to-ambient, for the minimum footprint is 220°C/W, taken from Table 1. The maximum power dissipation number cannot be exceeded for proper operation of the device. Using the output voltage of 3.3V, and an output current of 150mA, we can determine the maximum input voltage. Ground current, maximum of 3mA for 150mA of output current, can be taken from the “Electrical Characteristics” section of the data sheet. The MIC5219 will remain stable and in regulation with no load (other than the internal voltage divider) unlike many other voltage regulators. This is especially important in CMOS RAM keep-alive applications. Reference Bypass Capacitor BYP is connected to the internal voltage reference. A 470pF capacitor (CBYP) connected from BYP to GND quiets this reference, providing a significant reduction in output noise (ultra-low-noise performance). CBYP reduces the regulator phase margin; when using CBYP, output capacitors of 2.2µF or greater are generally required to maintain stability. The start-up speed of the MIC5219 is inversely proportional to the size of the reference bypass capacitor. Applications requiring a slow ramp-up of output voltage should consider larger values of CBYP. Likewise, if rapid turn-on is necessary, consider omitting CBYP. June 2009 P D (max ) = 455mW = (VIN – 3.3V) × 150mA + VIN × 3mA 455mW = (150mA) × VIN + 3mA × VIN – 495mW 950mW = 153mA × VIN VIN = 6.2VMAX Therefore, a 3.3V application at 150mA of output current can accept a maximum input voltage of 6.2V in a SOT-23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the “Regulator Thermals” section of Micrel’s Designing with Low-Dropout Voltage Regulators handbook. 9 M0371-061809 Micrel, Inc. MIC5219 Peak Current Applications xBMM, the power MSOP package part. These graphs show three typical operating regions at different temperatures. The lower the temperature, the larger the operating region. The graphs were obtained in a similar way to the graphs for the MIC5219-x.xBM5, taking all factors into consideration and using two different board layouts, minimum footprint and 1" square copper PC board heat sink. (For further discussion of PC board heat sink characteristics, refer to “Application Hint 17, Designing PC Board Heat Sinks” .) The MIC5219 is designed for applications where high start-up currents are demanded from space constrained regulators. This device will deliver 500mA start-up current from a SOT23-5 or MM8 package, allowing high power from a very low profile device. The MIC5219 can subsequently provide output current that is only limited by the thermal characteristics of the device. You can obtain higher continuous currents from the device with the proper design. This is easily proved with some thermal calculations. The information used to determine the safe operating regions can be obtained in a similar manner such as determining typical power dissipation, already discussed. Determining the maximum power dissipation based on the layout is the first step, this is done in the same manner as in the previous two sections. Then, a larger power dissipation number multiplied by a set maximum duty cycle would give that maximum power dissipation number for the layout. This is best shown through an example. If the application calls for 5V at 500mA for short pulses, but the only supply voltage available is 8V, then the duty cycle has to be adjusted to determine an average power that does not exceed the maximum power dissipation for the layout. If we look at a specific example, it may be easier to follow. The MIC5219 can be used to provide up to 500mA continuous output current. First, calculate the maximum power dissipation of the device, as was done in the thermal considerations section. Worst case thermal resistance (θJA = 220°C/W for the MIC5219-x.xBM5), will be used for this example. P D (max ) = ( T (max ) − T ) J A θ JA Assuming a 25°C room temperature, we have a maximum power dissipation number of P D (max ) = (125 °C − 25°C ) % DC Avg.P D = V – V OUT I OUT + V IN I GND 100 IN ( 220 °C / W PD(max) = 455mW Then we can determine the maximum input voltage for a 5-volt regulator operating at 500mA, using worst case ground current. PD(max) = 455mW = (VIN – VOUT) IOUT + VIN IGND IOUT = 500mA % DC 455mW = (8V – 5V ) 500mA + 8V × 20mA 100 % Duty Cycle 455mW = 1.66W 100 VOUT = 5V ) 0.274 = % Duty Cycle 100 % Duty Cycle Max = 27.4% IGND = 20mA 455mW = (VIN – 5V) 500mA + VIN × 20mA 2.995W = 520mA × VIN With an output current of 500mA and a three-volt drop across the MIC5219-xxBMM, the maximum duty cycle is 27.4%. 2.955W = 5.683V 520mA Applications also call for a set nominal current output with a greater amount of current needed for short durations. This is a tricky situation, but it is easily remedied. Calculate the average power dissipation for each current section, then add the two numbers giving the total power dissipation for the regulator. For example, if the regulator is operating normally at 50mA, but for 12.5% of the time it operates at 500mA output, the total power dissipation of the part can be easily determined. First, calculate the power dissipation of the device at 50mA. We will use the MIC5219-3.3BM5 with 5V input voltage as our example. VIN (max ) = Therefore, to be able to obtain a constant 500mA output current from the 5219-5.0BM5 at room temperature, you need extremely tight input-output voltage differential, barely above the maximum dropout voltage for that current rating. You can run the part from larger supply voltages if the proper precautions are taken. Varying the duty cycle using the enable pin can increase the power dissipation of the device by maintaining a lower average power figure. This is ideal for applications where high current is only needed in short bursts. Figure 1 shows the safe operating regions for the MIC5219-x. xBM5 at three different ambient temperatures and at different output currents. The data used to determine this figure assumed a minimum footprint PCB design for minimum heat sinking. Figure 2 incorporates the same factors as the first figure, but assumes a much better heat sink. A 1" square copper trace on the PC board reduces the thermal resistance of the device. This improved thermal resistance improves power dissipation and allows for a larger safe operating region. PD × 50mA = (5V – 3.3V) × 50mA + 5V × 650µA PD × 50mA = 173mW However, this is continuous power dissipation, the actual on‑time for the device at 50mA is (100%-12.5%) or 87.5% of the time, or 87.5% duty cycle. Therefore, PD must be multiplied by the duty cycle to obtain the actual average power dissipation at 50mA. Figures 3 and 4 show safe operating regions for the MIC5219-x. June 2009 10 M0371-061809 Micrel, Inc. MIC5219 10 10 10 100mA 8 6 4 400mA 20 40 60 80 DUTY CYCLE (%) 100 0 500mA a. 25°C Ambient 20 300mA 2 500mA 400mA 0 200mA 4 300mA 2 500mA 0 6 200mA 300mA 2 100mA 8 6 200mA 4 0 100mA 8 40 60 80 DUTY CYCLE (%) 100 0 400mA 0 b. 50°C Ambient 20 40 60 80 DUTY CYCLE (%) 100 c. 85°C Ambient Figure 1. MIC5219-x.xBM5 (SOT-23-5) on Minimum Recommended Footprint 10 10 10 100mA 8 8 8 100mA 100mA 200mA 6 6 300mA 4 400mA 2 200mA 4 0 20 2 40 60 80 DUTY CYCLE (%) 100 0 500mA 0 20 40 60 80 DUTY CYCLE (%) 100 40 60 80 DUTY CYCLE (%) 100 10 100mA 8 8 200mA 8 6 300mA 4 2 200mA 300mA 4 2 400mA 500mA 40 60 80 DUTY CYCLE (%) 100 0 0 a. 25°C Ambient 20 300mA 4 400mA 2 500mA 100mA 6 200mA 400mA 20 c. 85°C Ambient 10 100mA 20 0 b. 50°C Ambient 10 0 0 500mA Figure 2. MIC5219-x.xBM5 (SOT-23-5) on 1-inch2 Copper Cladding 6 300mA 2 400mA 400mA a. 25°C Ambient 0 200mA 4 300mA 500mA 0 6 40 60 80 DUTY CYCLE (%) 100 0 500mA 0 b. 50°C Ambient 20 40 60 80 DUTY CYCLE (%) 100 c. 85°C Ambient Figure 3. MIC5219-x.xBMM (MSOP-8) on Minimum Recommended Footprint 10 200mA 8 10 10 300mA 6 6 400mA 4 8 200mA 6 300mA 400mA 4 500mA 2 100mA 200mA 8 300mA 4 500mA 2 400mA 2 500mA 0 0 20 40 60 80 DUTY CYCLE (%) a. 25°C Ambient June 2009 100 0 0 20 40 60 80 DUTY CYCLE (%) b. 50°C Ambient 100 0 0 20 40 60 80 DUTY CYCLE (%) 100 c. 85°C Ambient Figure 4. MIC5219-x.xBMM (MSOP-8) on 1-inch2 Copper Cladding 11 M0371-061809 Micrel, Inc. MIC5219 PD × 50mA = 0.875 × 173mW VIN PD × 50mA = 151mW The power dissipation at 500mA must also be calculated. PD × 500mA = (5V – 3.3V) 500mA + 5V × 20mA Adjustable Regulator Circuits MIC5219 VIN IN OUT EN ADJ GND PD(total) = PD × 50mA + PD × 500mA PD(total) = 151mW + 119mW PD(total) = 270mW The total power dissipation of the regulator is less than the maximum power dissipation of the SOT-23-5 package at room temperature, on a minimum footprint board and therefore would operate properly. VOU T R1 1µF R2 Multilayer boards with a ground plane, wide traces near the pads, and large supply-bus lines will have better thermal conductivity. Figure 7. Low-Noise Adjustable Voltage Regulator Figure 7 shows the basic circuit for the MIC5219 adjustable regulator. The output voltage is configured by selecting values for R1 and R2 using the following formula: R2 V OUT = 1.242V + 1 R1 For additional heat sink characteristics, please refer to Micrel “Application Hint 17, Designing P.C. Board Heat Sinks”, included in Micrel’s Databook. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to “Regulator Thermals” section of Micrel’s Designing with LowDropout Voltage Regulators handbook. Although ADJ is a high-impedance input, for best performance, R2 should not exceed 470kΩ. MIC5219 VIN VOU T IN OUT R1 EN ADJ GND 2.2µF VOU T 1µF 470pF Figure 5. Low-Noise Fixed Voltage Regulator R2 Figure 8. Ultra-Low-Noise Adjustable Application Figure 5 shows a basic MIC5219‑x.xBMX fixed-voltage regulator circuit. A 1µF minimum output capacitor is required for basic fixed-voltage applications. June 2009 2.2µF Figure 6 includes the optional 470pF noise bypass capacitor between BYP and GND to reduce output noise. Note that the minimum value of COUT must be increased when the bypass capacitor is used. PD × = 119mW Fixed Regulator Circuits MIC5219-x.x VIN IN OUT EN BYP GND VOU T OUT BYP GND Figure 6. Ultra-Low-Noise Fixed Voltage Regulator PD × = 0.125 × 950mW The total power dissipation of the device under these conditions is the sum of the two power dissipation figures. IN EN 470pF PD × 500mA = 950mW This number must be multiplied by the duty cycle at which it would be operating, 12.5%. MIC5219-x.x Figure 8 includes the optional 470pF bypass capacitor from ADJ to GND to reduce output noise. 12 M0371-061809 Micrel, Inc. MIC5219 Package Information 8-Pin MSOP (MM) SOT-23-5 (M5) June 2009 13 M0371-061809 Micrel, Inc. MIC5219 6-Pin MLF® (ML) 6-Pin Thin MLF® (MT) 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. June 2009 14 M0371-061809