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mic47150 1.5a, low voltage, adjustable, high- bandwidth ldo regulator with dual input supplies *see thermal design section micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micre l.com october 2009 m9999-102309-a general description the mic47150 is a high-bandwidth, low-dropout, 1.5a volt- age regulator ideal for powering core voltages of low- power microprocessors. the mic47150 implements a dual supply con guration allowing for very low output impedance and very fast transient response. the mic47150 requires a bias input supply between 3v and 6.5v for proper operation. the main input supply rail operates from 1.4v to 6.5v that allows for adjustable output voltages down to 0.9v. the mic47150 requires a minimum of 1f output capacitance for stability, and opt imal operation is achieved with small ceramic capacitors. the mic47150 is available in a 5-pin power d-pak package (to-252) with an operating temperature range of ?40c to +125c. datasheets and support documentation can be found on micrel?s web site at www.micrel.com. features ? input voltage range: ? v in : 1.4v to 6.5v ? v bias : 3.0v to 6.5v ? stable with 1f ceramic capacitor ? 1% initial tolerance ? maximum dropout voltage (v in ?v out ) of 500mv over temperature ? adjustable output voltage down to 0.9v ? ultra fast transient response (up to 10mhz bandwidth) ? excellent line and load regulation specifications ? power d-pak package (to-252) ? thermal shutdown and current-limit protection ? junction temperature range: ?40c to +125c applications ? graphics processors ? pc add-in cards ? microprocessor core voltage supply ? low voltage digital ics ? high efficiency linear power supplies ? smps post regulators __________________________________________________________________________________________ typical application* figure 1. typical application circuit
micrel, inc. mic47150 october 2009 2 m9999-102309-a ordering information part number output current voltage junction temp. range package MIC47150WD* 1.5a adjustable ?40 to +125c 5-pin to-252 note: * rohs compliant with ?high-melting solder? exemption. pin configuration 5-pin to-252 d-pak (d) pin description pin number pin name pin name 1 adj adjustable regulator feedback input: connect to the resistor voltage divider that is placed from out to gnd in order to set the output voltage. 2 bias input bias voltage: voltage for powering all internal circuitry of the regulator with the exception of the output power device. 3 gnd, tab ground: tab is also connected internally to the ic?s ground on d-pak. 4 in input voltage: supplies the curr ent to the output power device 5 out regulator output: the output voltage is set by the resistor divider connected from out to gnd (with the divided connection tied to adj). a minimum value capacitor must be used to maintain stability. see applications information.
micrel, inc. mic47150 october 2009 3 m9999-102309-a absolute maximum ratings (1) supply voltage (v in ) ......................................... -0.3v to +8v bias supply voltage (v bias ).............................. -0.3v to +8v power dissipation .....................................in ternally limited esd rating (3) .................................................................. 2kv operating ratings (2) supply voltage (v in )..................................... +1.4v to +6.5v bias supply voltage (v bias )............................. +3v to +6.5v junction temperature (t j ) ..................?40c t j +125c package thermal resistance to-252 ( jc ) ........................................................3 c/w to-252 ( ja ).......................................................56c/w electrical characteristics (4) v in = v out + 1v, v bias = v out + 2.1v, i out = 10ma; t a = 25c, bold values indicate ?40c t j +125c, unless noted. symbol parameter condition min typ max units v lnreg line regulation v in = (v out +1v) to 6.5v ?0.1 0.01 +0.1 %/v v ldreg load regulation i out = 10ma to 1.5a 0.2 1.5 % v do dropout voltage (v in - v out ) i out = 750ma i out = 1.5a 130 280 300 500 mv mv v do(bias) dropout voltage (v bias - v out ), note 5 i out = 750ma i out = 1.5a 1.3 1.65 2.1 v i gnd ground pin current, note 6 i out = 10ma i out = 1.5a 15 15 30 ma i bias current thru v bias i out = 10ma i out = 1.5a 9 32 25 ma ma i lim current limit v out = 0v 1.6 2.3 3.4 4 a a t sd thermal shutdown 168 c thermal shutdown hysteresis 10 c reference (adjust pin) v adj reference voltage 0.891 0.882 0.9 0.909 0.918 v v i adj adjust pin current v adj = 1.2v 0.01 1 a notes: 1. exceeding the absolute maxi mum 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, 1.5k ? in series with 100pf. 4. specification for packaged product only. 5. for v out 1v, v bias dropout speci cation does not apply due to a minimum 3v v bias input. 6. i gnd = i bias + (i in ? i out ). at high loads, input current on v in will be less than the output current, due to drive current being supplied by v bias .
micrel, inc. mic47150 october 2009 4 m9999-102309-a typical characteristics
micrel, inc. mic47150 october 2009 5 m9999-102309-a typical characteristics (continued)
micrel, inc. mic47150 october 2009 6 m9999-102309-a functional characteristics
micrel, inc. mic47150 october 2009 7 m9999-102309-a functional description the mic47150 is an ultra-high performance, low-dropout linear regulator designed for high current applications requiring fast transient response. the mic47150 utilizes two input supplies, significantly reducing dropout voltage, perfect for low-voltage, dc-to-dc conversion. the mic47150 requires a minimum of external components and obtains a bandwidth of up to 10mhz. as a cap regulator, the output is tolerant of virtually any type of capacitor including ceramic type and tantalum type capacitors. the mic47150 regulator is fully protected from damage due to fault conditions, offering linear current limiting and thermal shutdown. bias supply voltage v bias , requiring relatively light current, provides power to the control portion of the mic47150. v bias requires approximately 32ma for a 1.5a load current. dropout conditions require higher currents. most of the biasing current is used to supply the base current to the pass transistor. this allows the pass element to be driven into saturation, reducing the dropout to 280mv at a 1.5a load current. bypassing on the bias pin is recommended to improve performance of t he regulator during line and load transients. small ceramic capacitors from v bias to ground help reduce high frequency noise from being injected into the control circuitry from the bias rail and are good design practice. good bypass techniques typically include one larger capacitor such as 1f ceramic and smaller valued capacitors such as 0.01f or 0.001f in parallel with that larger capacitor to decouple the bias supply. the v bias input voltage must be 2.1v above the output voltage with a minimum v bias input voltage of 3 volts. input supply voltage v in provides the high current to the collector of the pass transistor. the minimum input voltage is 1.4v, allowing conversion from low voltage supplies. output capacitor the mic47150 is designed to be stable with a minimal capacitance value and without esr constraints. however, proper capacitor selection is important to ensure desired transient response. a 1f ceramic chip capacitor should satisfy most applications and output capacitance can be increased without bound. see ? typical characteristic ? for examples of load transient response. x7r dielectric ceramic capacitors are recommended because of their temperatur e performance. x7r-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. z5u and y5v dielectric capacitors change value by as much as 50% and 60% respectively over their operating temperature ranges. to use a ceramic chip capacitor with y5v dielectric, the value must be much higher than an x7r ceramic or a tantalum capacitor to ensure the same capacitance value over the operating temperature range. tantalum capacitors have a very stable dielectric (10% over their operating temperature range) and can also be used with this device. input capacitor additional bypass capacitance is recommended when the device is more than 2 to 3 inches away from the bulk supply capacitance, or w hen the supply is a battery. small, surface-mount, ceramic chip capacitors can be used for the bypassing. a 1 f or greater ceramic input capacitor should be placed next to the device for optimal performance. larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage. thermal design linear regulators are simple to use. the most complicated design parameters to consider are thermal characteristics. thermal design requires the following application-specific parameters: ? maximum ambient temperature (t a ) ? output current (i out ) ? output voltage (v out ) ? input voltage (v in ) ? ground current (i gnd ) first, calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet. p d = v in i in + v bias i bias ? v out i out the input current will be less than the output current at high output currents as the load increases. the bias current is a sum of base drive and ground current. ground current is constant over load current. then the heat sink thermal resistance is determined with this formula: () cs jc d a j(max) sa p t t + ? ? ? ? ? ? ? ? ? ? = the heat sink may be significantly reduced in applications where the maximum input voltage is known and large compared with the dropout voltage. use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. the low-dropout properties of the mic47150 allow significant reductions in regulator power dissipation and the associated heat sink without compromising performance. when this technique is employed, a
micrel, inc. mic47150 october 2009 8 m9999-102309-a capacitor of at least 1f is needed directly between the input and regulator ground. refer to ? application note 9 ? for further details and examples on thermal design and heat sink specifications. the maximum power allowed can be calculated using the thermal resistance ( ja ) of the d-pak adhering to the following criteria for the pcb design: 2 oz. copper and 100mm 2 copper area for the mic47150. given a maximum ambient temperature (t a =75 c), and without the use of a heat sink, the maximum power allowed that would not exceed the ic?s maximum junction temperature (125 c) is p d(max) = (t j(max) ? t a )/ ja = (125 c ? 75 c)/(56 c/w) = 0.893w minimum load current the mic47150, unlike most other high current regulators, does not require a minimum load to maintain output voltage regulation.
micrel, inc. mic47150 october 2009 9 m9999-102309-a application information adjustable regulator design the mic47150 allows programming the output down to 0.9v. from the typical application in figure 1, the output voltage is set by placing a resistor divider network from out to gnd and is determined by the following equation: ? ? ? ? ? ? + = 1 r2 r1 0.9 v out where v out is the desired output voltage. the resistor value between v out and the adjust pin should not exceed 10k ? . larger values can cause instability. the resistor val ues are calculated from the above equation, resulting in the following: ? ? ? ? ? ? ? ? ? = 1 0.9 v r2 r1 out evb layout the mic47150 evaluation board layout is shown in figures 2 and 3. for customer application boards, recommended variations include using a static resistor for r2 in place of the potentiometer as well as the elimination of all test points and jumper options that are included on the mic47150 evaluation board. figure 2. mic47150 evb top layer figure 3. mic47150 evb bottom layer
micrel, inc. mic47150 october 2009 10 m9999-102309-a evaluation board bill of materials item part number manufacturer description qty. c1 c1206c106k8ractu kemet (1) ceramic capacitor, 10f, 10v, x7r 1 c2 c0805c105k8ractu kemet (1) ceramic capacitor, 1f, 10v, x7r 1 c3 c0805c105k8ractu kemet (1) ceramic capacitor, 1f, 10v, x7r 1 r1 crcw08051800f vishay (2) resistor, 180 ? , film, 0805 1 r2 pv36w502c01b00 murata (3) 5k ? potentiometer 1 u1 MIC47150WD micrel, inc. (4) mic47150 ldo regulator 1 notes: 1. kemet: www.kemet.com 2. vishay: www.vishay.com 3. murata: www.murata.com 4. micrel, inc.: www.micrel.com
micrel, inc. mic47150 october 2009 11 m9999-102309-a package information 5-pin to-252 power d-pak (d) 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 belie ved to be accurate and reliable. however, no responsibility is a ssumed 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 authori zed for use as components in life support app liances, devices or systems where malfu nction of a product can reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended 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 significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, 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.

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