general description the MAX8891/max8892 low-dropout (ldo) linear regu- lators are designed to deliver up to 150ma continuous output current. these regulators achieve a low 120mv dropout for 120ma load current. the MAX8891 only requires an input/output capacitor, hence achieving the smallest pcb area. the max8892? output voltage can be adjusted with an external divider. the MAX8891 is preset to a variety of voltages in the 1.5v to 4.5v range. designed with a p-channel mosfet series pass transistor, the MAX8891/max8892 maintain very low ground current (40?). the regulators are designed and optimized to work with low-value, low-cost ceramic capacitors. the MAX8891/ max8892 require only 1? (typ) of output capacitance for stability with any load. when disabled, current con- sumption drops to below 1?. these regulators are available in a tiny 5-pin sc70 package. applications cellular and cordless phones pda and palmtop computers base stations bluetooth portable radios and accessories wireless lans digital cameras personal stereos portable and battery-powered equipment features ? space-saving sc70 package ? 65db psrr at 10khz ? 120mv dropout at 120ma load ? stable with 1? ceramic capacitor for any load ? guaranteed 150ma output ? only need input and output capacitors (MAX8891) ? output voltages: 1.5v, 1.8v, 2.5v, 2.6v, 2.7v, 2.8v, 2.85v, 3v, 3.3v, 4.5v (MAX8891) and adjustable (max8892) ? low 40? ground current ? excellent load/line transient ? overcurrent and thermal protection MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators ________________________________________________________________ maxim integrated products 1 gnd n.c. (MAX8891) fb (max8892) shdn 1 2 3 5 4 out in MAX8891/ max8892 sc70 + top view pin configuration MAX8891 output preset 1.5v to 4.5v in input 2v to 6v off shdn c out = 1 f c in = 1 f out on gnd max8892 output adjustable 1.5v to 4.5v in input 2v to 6v off shdn r1 r2 c out = 1 f c in = 1 f out on fb gnd typical operating circuits ordering information 19-4537; rev 0; 3/09 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. * xy is the output voltage code (see output voltage selector guide). other versions between 1.5v and 4.5v are available in 100mv increments. contact factory for other versions. + denotes a lead(pb)-free/rohs-compliant package. part* temp range pin-package MAX8891 exkxy+t -40? to +85? 5 sc70 max8892 exk+t -40? to +85? 5 sc70 output voltage selector guide appears at end of data sheet.
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = v out + 0.5v, t a = -40? to +85?, unless otherwise noted. c in = 1?, c out = 1?. typical values are at t a = +25?; the max8892 is tested with 2.45v output, unless otherwise noted.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in to gnd .................................................................-0.3v to +7v output short-circuit duration.....................................continuous out, shdn to gnd ......................................-0.3v to (in + 0.3v) fb, bp, n.c. to gnd..................................-0.3v to (out + 0.3v) continuous power dissipation (t a = +70?) 5-pin sc70 (derate 3.1mw/? above +70?) ..............0.247w ja 5-pin sc70 .................................................................324?/w operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol conditions min typ max units input voltage range v in 26v output voltage accuracy i out = 100? to 80ma -3 +3 % maximum output current i out 150 ma current limit i lim out = 90% of nominal value 200 ma v out 3v, i out = 120ma 120 2.5v v out < 3v, i out = 120ma 135 dropout voltage (note 2) 2v v out < 2.5v, i out = 120ma 180 mv ground current i q i out = 0.05ma 40 a line regulation v lnr v in = (v out + 0.5v) to 6v, i out = 0.1ma 0.001 %/v load regulation v ldr i out = 1ma to 80ma 0.003 %/ma t a = +25? 0.003 1 shutdown supply current i shdn shdn = 0v t a = +85? 0.05 ? ripple rejection psrr f = 10khz, i out = 10ma 65 db output noise voltage (rms) f = 100hz to 100khz, i load = 80ma 230 ? shdn logic-low level v in = 2v to 6v 0.4 v shdn logic-high level v in = 2v to 6v 1.5 v t a = +25? shdn input bias current v in = 6v, shdn = 0v or 6v t a = +85? 0.01 ? t a = +25? 0.006 0.1 fb input bias current (max8892) v in = 6v, v fb = 1.3v t a = +85? 0.01 ? thermal shutdown 160 ? thermal-shutdown hysteresis 10 ? note 1: limits are 100% tested at t a = +25?. limits over operating temperature range are guaranteed by design. note 2: dropout is defined as v in - v out when v out is 100mv below the value of v out for v in = v out + 0.5v.
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators _______________________________________________________________________________________ 3 dropout voltage vs. load current MAX8891/2 toc04 load current (ma) dropout voltage (mv)) 125 100 75 50 25 40 80 120 160 200 0 60 100 140 180 20 0150 t a = +85 c t a = +25 c t a = -40 c dropout voltage vs. output voltage MAX8891/2 toc05 output (v) dropout voltage (mv) 3.0 2.8 2.6 2.4 2.2 50 100 150 200 250 0 2.0 3.2 i out = 80ma ground pin current vs. input voltage MAX8891/2 toc06 input voltage (v) ground pin current ( a) 4 3 2 1 150 200 50 100 250 300 350 0 05 i out = 0ma ground pin current vs. load current MAX8891/2 toc07 load current (ma) ground pin current ( a) 125 100 75 50 25 50 100 150 200 250 300 350 0 0 150 v in = 3.8v v in = 5.5v ground pin current vs. temperature MAX8891/2 toc08 temperature ( c) ground pin current ( a) 60 35 10 -15 35 40 45 50 30 -40 85 typical operating characteristics (v in = v out + 0.5v, c in = 1?, c out = 1?, t a = +25?, unless otherwise noted.) output voltage vs. input voltage MAX8891/2 toc01 input voltage (v) output voltage (v) 5 4 3 2 1 0.5 1.0 1.5 2.0 2.5 3.0 0.0 06 i out = 120ma i out = 0ma output voltage accuracy vs. load current MAX8891/2 toc02 load current (ma) % deviation (%) 125 100 75 50 25 -0.4 -0.2 0 0.2 0.4 0.6 -0.6 0150 output voltage accuracy vs. temperature MAX8891/2 toc03 temperature ( c) % deviation (%) 60 35 10 -15 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 -40 85 i out = 1ma psrr vs. frequency MAX8891/2 toc09 frequency (khz) psrr (db) 0.1 1 10 100 40 50 60 10 20 30 70 80 90 0 0.01 1000 i load = 10ma
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators 4 _______________________________________________________________________________________ load transient response dl/dt = 0.5ma/ s MAX8891/2 toc10 200 s 10ma 10ma load transient response dl/dt = 5ma/ s MAX8891/2 toc11 20 s 10ma 10ma load transient response dl/dt = 20ma/ s MAX8891/2 toc12 4 s 10ma 10ma startup waveform MAX8891/2 toc13 10 v shdn 2v/div v out 500mv/div on off shutdown waveform MAX8891/2 toc14 40 v out 500mv/div v shdn 2v/div on off line transient response dv/dt = 500mv/ s MAX8891/2 toc15 40 v in 500mv/div v out 10mv/div 3.5v dv/dt = 500mv/ s 4v 4v line transient response dv/dt = 200mv/ s MAX8891/2 toc16 40 v in 1v/div v out 10mv/div 3.5v dv/dt = 200mv/ s 5v 5v region of stable c out esr vs. load current MAX8891/2 to17 load current (ma) c out esr ( ) 75 100 25 125 50 0.1 1 10 100 0.01 0 150 stable region typical operating characteristics (continued) (v in = v out + 0.5v, c in = 1?, c out = 1?, t a = +25?, unless otherwise noted.)
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators _______________________________________________________________________________________ 5 _______________________________________________________________________________________ 5 detailed description the MAX8891/max8892 are low-dropout, low-quies- cent current linear regulators designed for space- restricted applications. the parts are available with preset output voltages ranging from 1.5v to 4.5v in 100mv increments. these devices can supply loads up to 150ma. as shown in the functional diagram , the MAX8891 consists of an innovative bandgap core, error amplifier, p-channel pass transistor, and internal feed- back voltage-divider. the max8892 allows for adjustable output with an external feedback network. additional blocks include a current limiter, thermal sen- sor, and shutdown logic. the 1.225v bandgap reference is connected to the error amplifier? inverting input. the error amplifier com- pares this reference with the feedback voltage and amplifies the difference. if the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled low. this allows more current to pass to the out- put and increases the output voltage. if the feedback voltage is too high, the pass transistor gate is pulled high, allowing less current to pass to the output. the output voltage is fed back through an internal (external for the max8892) resistor voltage-divider connected to the out pin. internal p-channel pass transistor the MAX8891/max8892 feature a 1 (typ) p-channel mosfet pass transistor. this provides several advan- tages over similar designs using a pnp pass transistor, including longer battery life. the p-channel mosfet requires no base drive, which considerably reduces qui- escent current. pnp-based regulators waste consider- able current in dropout when the pass transistor saturates. they also use high base-drive current under heavy loads. the MAX8891/max8892 do not suffer from these problems and consume only 40? of quiescent current in light load and 220? in dropout (see the typical operating characteristics ). output voltage selection the MAX8891 is supplied with factory-set output volt- ages from 1.5v to 4.5v, in 100mv increments (see the ordering information ). the max8892 features a user- adjustable output through an external feedback net- work (see the typical operating circuits ). to set the output of the max8892, use the following equation: where r2 is chosen to be less than 240k and v ref = 1.225v. use 1% or better resistors. shutdown the MAX8891/max8892 feature a low-power shutdown mode that reduces quiescent current less than 1?. driving shdn low disables the voltage reference, error amplifier, gate-drive circuitry, and pass transistor (see the functional diagram ), and the device output enters a high-impedance state. connect shdn to in for normal operation. current limit the MAX8891/max8892 include a current limiter, which monitors and controls the pass transistor? gate volt- age, limiting the output current to 200ma. the output can be continuously shorted to ground without damag- ing the part. rrx v v out ref 12 1 = ? ? ? ? ? ? - pin description pin MAX8891 max8892 name function 1 1 in unregulated input supply 2 2 gnd ground 33 shdn shutdown. pull low to disable the regulator. 4 fb adjustable output feedback point 4 n.c. not internally connected 5 5 out reg ul ated outp ut v ol tag e. byp ass w i th a cap aci tor to gn d . s ee the c ap aci tor s el ecti on and reg ul ator s tab i l i ty secti on for m or e d etai l s.
thermal-overload protection thermal-overload protection limits total power dissipation in the MAX8891/max8892. when the junction tempera- ture exceeds t j = +160?, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the ic to cool down. the thermal sensor turns the pass transistor on again after the ic? junction tem- perature drops by 10?, resulting in a pulsed output dur- ing continuous thermal-overload conditions. thermal-overload protection is designed to protect the MAX8891/max8892 in the event of a fault condition. for continual operation, do not exceed the absolute maxi- mum junction temperature rating of t j = +150?. operating region and power dissipation the MAX8891/max8892 maximum power dissipation depends on the thermal resistance of the case and cir- cuit board, the temperature difference between the die junction and ambient, and the rate of airflow. the power dissipation across the device is: p = i out (v in - v out ) the maximum power dissipation is: p max = (t j - t a )/( jc + ca ) where t j - t a is the temperature difference between the MAX8891/max8892 die junction and the surrounding air, jc is the thermal resistance of the package, and ca is the thermal resistance through the pcb, copper traces, and other materials to the surrounding air. the gnd pin of the MAX8891/max8892 performs the dual function of providing an electrical connection to ground and channeling heat away. connect the gnd pin to ground using a large pad or ground plane. applications information capacitor selection and regulator stability use a 1? capacitor on the MAX8891/max8892 input and a 1? capacitor on the output. larger input capacitor values and lower esrs provide better noise rejection and line-transient response. reduce output noise and improve load-transient response, stability, and power- supply rejection by using large output capacitors. note that some ceramic dielectrics exhibit large capacitance and esr variation with temperature. with dielectrics such as z5u and y5v, it may be necessary to use a 2.2? or larger output capacitor to ensure stability at temperatures below -10?. with x7r or x5r dielectrics, 1? is sufficient at all operating temperatures. a graph of the region of stable c out esr vs. load current is shown in the typical operating characteristics . psrr and transient response the MAX8891/max8892 are designed to deliver high psrr as well as low dropout and low quiescent currents in battery-powered systems. the MAX8891/ max8892 power-supply rejection is 65db at 10khz. when operating from sources other than batteries, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors, and through passive fil- tering techniques. the typical operating characteristics show the MAX8891/max8892 line- and load-transient responses. dropout voltage a regulator? minimum dropout voltage determines the lowest usable supply voltage. in battery-powered systems, this determines the useful end-of-life battery voltage. because the MAX8891/max8892 use a p-channel mosfet pass transistor, their dropout volt- age is a function of drain-to-source on-resistance (r ds(on) ) multiplied by the load current (see the typical operating characteristics ). MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators 6 _______________________________________________________________________________________
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators _______________________________________________________________________________________ 7 p out fb** *MAX8891 only **max8892 only * * MAX8891/ max8892 error amp in shdn gnd shutdown and power-on control thermal sensor mos driver with i limit 1.225v reference functional diagram chip information process: bicmos output voltage selector guide part v out (v) top mark MAX8891exk15+t 1.5 ati MAX8891exk18+t 1.8 atj MAX8891exk25+t 2.5 atl MAX8891exk26+t 2.6 atm MAX8891exk28+t 2.8 ato MAX8891exk29+t 2.85 atp MAX8891exk89+t 2.9 atv MAX8891exk31+t 3.1 atr MAX8891exk33+t 3.3 ats MAX8891exk45+t 4.5 atu max8892exk+t adjustable atw note: standard output voltage options, shown in bold , are available. contact the factory for other output voltages between 1.5v and 4.5v. minimum order quantity is 15,000 units.
MAX8891/max8892 high psrr, low-dropout, 150ma linear regulators maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 8 _____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. package type package code document no. 5 sc70 x5-1 21-0076 package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . sc70, 5l.eps package outline, 5l sc70 21-0076 1 1 e
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