MIC5237 500mA Low-Dropout Regulator General Description Features The MIC5237 is a general-purpose low-dropout regulator • Guaranteed 500mA output over the full operating capable of 500mA output current with better than 3% temperature range output voltage accuracy. Using Micrel’s proprietary Super • Low 300mV typical dropout voltage at full load ßeta PNP® process with a PNP pass element, these • Extremely tight load and line regulation regulators feature less than 300mV dropout voltage and typically 8mA ground current at full load. • Current and thermal limiting • Reversed-battery protection Designed for applications that require moderate current over a broad input voltage range, including hand-held and • TO-220 and TO-263 packages battery-powered devices, the MIC5237 is intended for • Low temperature coefficient applications that can tolerate moderate voltage drop at • No-load stability higher current. • Low-noise output Key features include low ground current to help prolong battery life, reversed-battery protection, current limiting, over-temperature shutdown, and thermally efficient Applications packaging. The MIC5237 is available in fixed output • Portable and laptop computers voltages only. • Desktop computer For space-critical applications and improved performance, see the MIC5209 and MIC5219. For output current • Battery chargers requirements up to 750mA, see the MIC2937. • SMPS post-regulator/dc-to-dc modules Data sheets and support documentation can be found on • Consumer and personal electronics Micrel’s web site at: www.micrel.com. ___________________________________________________________________________________________________________ Typical Application Super βeta PNP 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 2007 M9999-090607-C

Micrel, Inc. MIC5237 Ordering Information Part Number Voltage Junction Temp. Range Package Standard Pb-Free MIC5237-2.5BU MIC5237-2.5YU 2.5V –40° to +125°C TO-263-3 MIC5237-3.3BU MIC5237-3.3YU 3.3V –40° to +125°C TO-263-3 MIC5237-5.0BT MIC5237-5.0YT 5.0V –40° to +125°C TO-220-3 MIC5237-5.0BU MIC5237-5.0YU 5.0V –40° to +125°C TO-263-3 Pin Configuration TO-220-3 (T) TO-263-3 (U) Pin Description Pin Number Pin Name Pin Function 1 IN Supply Input. 2, TAB GND Ground: TO-220 and TO-263 pin 2 and TAB are internally connected. 3 OUT Regulator Output. September 2007 2 M9999-090607-C

Micrel, Inc. MIC5237 Absolute Maximum Ratings(1) Operating Ratings Supply Voltage (V )..........................................–20 to +20V Supply Voltage (V )......................................+2.5V to +16V IN IN Power Dissipation (P )..............................Internally Limited Junction Temperature (T )........................–40°C to +125°C D J Lead Temperature (soldering, 5 sec.)........................260°C Package Thermal Resistance TO-220 (θ ).......................................................55°C/W JA TO-220 (θ )........................................................3°C/W JC TO-263 (θ )........................................................3°C/W JC Electrical Characteristics V = V + 1.0V; C = 4.7µF; I = 100µA; T = 25°C, bold values indicate –40°C< T < +125°C, unless noted. IN OUT OUT OUT J J Symbol Parameter Condition Min Typ Max Units V Output Voltage Accuracy variation from nominal V –3 3 % OUT OUT –5 5 % ∆V /∆T Output Voltage Note 2 40 ppm/°C OUT Temperature Coefficient ∆V /V Line Regulation V = V + 1V to 16V 0.05 %/V OUT OUT IN OUT 0.015 0.1 %/V ∆V /V Load Regulation I = 100µA to 500mA, Note 3 0.05 0.5 % OUT OUT OUT 0.7 % V – V Dropout Voltage, Note 4 I = 100µA 10 70 mV IN OUT OUT 90 mV I = 50mA 115 190 mV OUT 280 mV I = 150mA 165 350 mV OUT 450 mV I = 500mA 300 600 mV OUT 700 mV I Ground Pin Current, Note 5 I = 100µA 80 130 µA GND OUT 170 µA I = 50mA 350 650 µA OUT 900 µA I = 150mA 1.8 2.5 mA OUT 3.0 mA I = 500mA 8 15 mA OUT 20 mA PSRR Ripple Rejection f = 120Hz 75 dB I Current Limit V = 0V 700 900 mA LIMIT OUT 1000 mA ∆V /∆P Thermal Regulation Note 6 0.05 %/W OUT D e Output Noise V = 5.0V, I = 50Ma, C = 2.2µF 500 nV/√Hz no OUT OUT OUT September 2007 3 M9999-090607-C

Micrel, Inc. MIC5237 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, T , the J(max) junction-to-ambient thermal resistance, θ , and the ambient temperature, T . The maximum allowable power dissipation at any ambient temperature JA A is calculated using: P = (T –T ) ÷ θ . Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the D(max) J(max) A JA regulator will go into thermal shutdown. See the “Thermal Considerations” section for details. 2. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. 3. 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. 4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1Vdifferential. 5. 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. 6. 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 V = 16V for t = 10ms. IN September 2007 4 M9999-090607-C

Micrel, Inc. MIC5237 Typical Characteristics Power Supply Power Supply Power Supply Rejection Ratio Rejection Ratio Rejection Ratio 0 0 0 VIN = 6V VIN = 6V VIN = 6V -20 VOUT = 5V -20 VOUT = 5V -20 VOUT = 5V )B -40 )B -40 )B -40 d d d ( ( ( R R R R R R S -60 S -60 S -60 P P P -80 IOUT = 100µA -80 IOUT = 1mA -80 IOUT = 100mA COUT = 1µF COUT = 1µF COUT = 1µF -100 -100 -100 1E10+111E0+021E1k+311E0+k411E0+05k1E1M+611E0M+7 1E10+111E0+021E1k+311E0+k411E0+05k1E1M+611E0M+7 1E10+111E0+021E1k+311E0+k411E0+05k1E1M+611E0M+7 FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) Power Supply Ripple Rejection vs. Voltage Drop Noise Performance 60 10 )B50 d 1 100mA (NO40 1mA )zH ITC /V 0.1 10mA EJER30 10mA IOUT = 100mA (ESµ 0.01 E20 IO L N V = 5V 1mA P OUT PIR10 COUT = 1µF 0.001 COUT = 10µF electrolytic 0 0.0001 0 0.1 0.2 0.3 0.4 11E0+111E0+021E1k+311E0+k411E00+5k1E1M+611E0M+7 VOLTAGE DROP (V) FREQUENCY (Hz) September 2007 5 M9999-090607-C

Micrel, Inc. MIC5237 Block Diagram Fixed Regulator September 2007 6 M9999-090607-C

Micrel, Inc. MIC5237 Application Information read from the data sheet. Assuming the worst case scenario is good design procedure, and the corresponding The MIC5237 is intended for general-purpose use and can ground current number can be obtained from the data be implemented in a wide variety of applications where sheet. First, calculate the power dissipation of the device. 500mA of output current is needed. It is available in several This example uses the MIC5237-5.0BT, a 13V input, and voltage options for ease of use. For voltage options that are 500mA output current, which results in 20mA of ground not available on the MIC5237, consult the MIC5209 for a current, worst case. The power dissipation is the sum of 500mA adjustable LDO regulator, or the MIC5219 for two power calculations: voltage drop × output current and applications that require only short-duration peak output input voltage × ground current. current. P = [(V – V ) × I ] + (V × I ) D IN OUT OUT IN GND Input Capacitor P = [(13V – 5V) × 500mA] + (13V × 20mA) D A 1µF capacitor should be placed from IN to GND if there is P = 4.260W D more than 10 inches of wire between the input and the ac From this number, the heat sink thermal resistance is filter capacitor or if a battery is used as the input. determined using the regulator’s maximum operating Output Capacitor junction temperature (TJ(max)) and the ambient temperature (T ) along with the power dissipation number already An output capacitor is required between OUT and GND to A calculated. prevent oscillation. 1µF minimum is recommended for standard applications. Larger values improve the T = 125°C J(MAX) regulator’s transient response. The output capacitor value θ = junction-to-case thermal resistance JC may be increased without limit. θ = case-to-sink thermal resistance CS The output capacitor should have an ESR (equivalent θ = junction-to-ambient thermal resistance series resistance) of about 5Ω or less and a resonant JA θ = sink-to-ambient thermal resistance frequency above 1MHz. Ultra low-ESR capacitors can SA cause low-amplitude oscillations and/or under-damped To determine the heat sink thermal resistance, the junction- transient response. Most tantalum or aluminum electrolytic to-case thermal resistance of the device must be used capacitors are adequate; film types will work, but are more along with the case-to-heat sink thermal resistance. These expensive. Since many aluminum electrolytics have numbers show the heat-sink thermal resistance required at electrolytes that freeze at about –30°C, solid tantalums are T =25°C that does not exceed the maximum operating A recommended for operation below –25°C. junction temperature. At lower values of output current, less output capacitance is T - T J(max) A needed for output stability. The capacitor can be reduced to θJA = P 0.47µF for current below 10mA or 0.33µF for currents D below 1mA. θ = θ - θ SA JA JC For 2.5V applications a 22µF output capacitor is recom- θ is approximately 1°C/W and θ for the TO-220 is CS JC mended to reduce startup voltage overshoot. 3°C/W in this example. 125 - 25 No-Load Stability θ = JA The MIC5237 will remain stable and in regulation with no 4.260W load (other than the internal voltage divider) unlike many θ = 23.5°C/W JA other voltage regulators. This is especially important in θ = 23.5°C/W – (3°C/W + 1°C/W) CMOSRAM keep-alive applications. SA θ = 19.5°C/W SA Thermal Considerations Therefore, a heat sink with a thermal resistance of Proper thermal design can be accomplished with some 19.5°C/W will allow the part to operate safely and it will not basic design criteria and some simple equations. The exceed the maximum junction temperature of the device. following information is required to implement a regulator The heat sink can be reduced by limiting power dissipation, design. by reducing the input voltage or output current. Either the V = input voltage TO-220 or TO-263 package can operate reliably at 2W of IN power dissipation without a heat sink. Above 2W, a heat V = output voltage OUT sink is recommended. I = output current OUT For a full discussion on voltage regulator thermal effects, T = ambient operating temperature A please refer to “Thermal Management” in Micrel’s I = ground current Designing with Low-Dropout Voltage Regulators handbook. GND The regulator ground current, I , can be measured or GND September 2007 7 M9999-090607-C

Micrel, Inc. MIC5237 Package Information 3-Pin TO-220 (T) 3-Pin TO-263 (U) September 2007 8 M9999-090607-C

Micrel, Inc. MIC5237 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. © 2000 Micrel, Incorporated. September 2007 9 M9999-090607-C

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M icrochip: MIC5237-5.0YT MIC5237-5.0YU MIC5237-3.3YU MIC5237-3.3YU TR MIC5237-5.0YU TR MIC5237-2.5YU MIC5237-5.0YU-TR MIC5237-3.3YU-TR MIC5237-2.5YU-TR