general description the max8887/max8888 low-dropout linear regulators operate from a +2.5v to +5.5v input and deliver up to 300ma continuous (500ma pulsed) current. the max8887 is optimized for low-noise operation, while the max8888 includes an open-drain pok ouput flag. both regulators feature exceptionally low 100mv dropout at 200ma. these devices are available in a variety of pre- set output voltages in the +1.5v to +3.3v range. an internal pmos pass transistor allows the low 55? supply current to remain independent of load, making these devices ideal for portable battery-powered equip- ment such as personal digital assistants (pdas), cellu- lar phones, cordless phones, and notebook computers. other features include a micropower shutdown mode, short-circuit protection, thermal shutdown protection, and an active-low open-drain power-ok (pok) output that indicates when the output is out of regulation. the max8887/max8888 are available in a thin 5-pin sot23 package that is only 1mm high. ________________________applications notebook computers wireless handsets pdas and palmtop computers digital cameras pcmcia cards hand-held instruments features guaranteed 300ma ouput current (500ma for pulsed loads) low 100mv dropout at 200ma load pok output (max8888) 42? rms ouput noise (max8887) preset output voltages (1.5v, 1.8v, 2.85v, and 3.3v) 55? no-load supply current thermal-overload and short?ircuit protection foldback ouput current-limit protection 60db psrr at 1khz 0.1? shutdown current thin 5-pin sot23 package, 1mm high max8887/max8888 low-dropout, 300ma linear regulators in sot23 ________________________________________________________________ maxim integrated products 1 gnd bp shdn 15 out in max8887 top view 2 34 gnd pok shdn 15 out in max8888 2 34 pin configurations max8887 max8888 on off input +2.5v to +5.5v in shdn gnd (bp) pok out v out 300ma c in 2.2 f c out 2.2 f c bp 0.01 f ( ) are for max8887 only. typical operating circuit 19-1859; rev 0; 12/00 for price, delivery, and to place orders, please contact maxim distribution at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information part temp range pin- package top mark m a x8 8 8 7 e z k15 -40 c to +85 c 5-sot23 adqd max8887ezk18 -40 c to +85 c 5-sot23 adpx max8887ezk29 -40 c to +85 c 5-sot23 adpy max8887ezk33 -40 c to +85 c 5-sot23 adpz max8887ezkxy* -40 c to +85 c 5-sot23 m a x8 8 8 8 e z k15 -40 c to +85 c 5-sot23 adqe max8888ezk18 -40 c to +85 c 5-sot23 adqa max8888ezk29 -40 c to +85 c 5-sot23 adqb max8888ezk33 -40 c to +85 c 5-sot23 adqc max8888ezkxy* -40 c to +85 c 5-sot23 * other versions (xy) between +1.5 and +3.3v are available in 100mv increments. contact factory for other versions. minimum order quantity is 25,000 units.
max8887/max8888 low-dropout, 300ma linear regulators in sot23 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = v out + 1v, shdn = in, t a = -40? to +85?, 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, shdn , pok, to gnd........................................-0.3v to +6.0v out, bp to gnd ............................................-0.3 to (v in + 0.3v) output short-circuit duration.....................................continuous continuous power dissipation (t a = +70 c) 5-pin sot23 (derate 9.1mw/ c above +70 c)............727mw operating temperature ranges..........................-40 c to +85 c junction temperature ......................................................+150 c storage temperature range .............................-65 c to +150 c lead temperature (soldering, 10s) .................................+500 c parameter symbol conditions min typ max units input voltage v in 2.5 5.5 v input undervoltage lockout v in rising (2% typical hysteresis) 2.15 2.4 v t a = +25 c, i out = 100ma -1.2 +1.2 i out = 100 a to 300ma, t a = 0 c to +85 c -2 +2 output voltage accuracy i out = 100 a to 300ma -3 +3 % continuous 300 maximum output current 10ms pulse 500 ma v out = 0 300 current limit v out > 93% of nominal value 420 ma no load 55 100 ground-pin current i out = 300ma 65 a i out = 1ma 0.5 i out = 200ma 100 200 dropout voltage (note 2) v out = +3.3v i out = 300ma 150 mv line regulation v in =2.5v or (v out + 0.4v) to 5.5v, i out = 5ma -0.15 0 0.15 %/v max8887 10hz to 100khz, c bp = 0.01 f, c out = 2.2 f, esr cout < 0.1 ? 42 output noise max8888 10hz to 100khz, c out = 2.2 f, esr cout < 0.1 ? 360 v rms max8887 f < 1khz, c bp = 0.01 f, c out = 4.7 f, esr cout < 0.1 ? 60 psrr max8888 f < 1khz, c out = 2.2 f, esr cout < 0.1 ? 40 db
max8887/max8888 low-dropout, 300ma linear regulators in sot23 _______________________________________________________________________________________ 3 parameter symbol conditions min typ max units shutdown shutdown supply current shdn = gnd, v in = 5.5v 0.1 2 a v ih 2.5v v in 5.5v 1.6 shdn input threshold v il 2.5v v in 5.5v 0.6 v shdn input bias current shdn = in or gnd 10 100 na out discharge resistance in shutdown shdn = gnd 650 1100 ? pok (max8888 only) pok trip level, referred to out set point v out falling (1% typical hysteresis) 90 92.5 95 % operating in voltage range for valid pok 1.0 5.5 v pok output voltage low v ol i sink = 1ma 0.1 v pok output leakage current v pok = 5.5v, shdn = in 100 na thermal protection thermal shutdown temperature 170 c thermal shutdown hysteresis 20 c electrical characteristics (continued) (v in = v out + 1v, shdn = in, t a = -40 c to +85 c, unless otherwise noted.) (note 1) note 1: all parts are 100% tested at t a = +25 c. limits over the operating temperature range are guaranteed by design. note 2: typical and maximum dropout voltage for different output voltages are shown in typical operating characteristics curve. typical operating characteristics ( typical operating circuit , t a = +25 c, unless otherwise noted.) 0 1.0 0.5 2.0 1.5 3.0 2.5 3.5 2.0 3.0 3.5 2.5 4.0 4.5 5.0 5.5 output voltage vs. input voltage max8887-8 toc01 input voltage (v) output voltage (v) i out = 0 i out = 300ma -1.0 -0.6 -0.8 0.0 -0.2 -0.4 0.2 0.4 0.8 0.6 1.0 100 50 150 200 250 300 output voltage accuracy vs. load current max8887-8 toc02 load current (ma) % deviation (%) 0 -0.05 -0.02 -0.03 -0.04 -0.01 0.0 0.01 0.02 0.03 0.04 0.05 -40 10 -15 356085 output voltage accuracy vs. temperature max8887-8 toc03 temperature ( c) % deviation i out = 0 v in = v out + 500mv
max8887/max8888 low-dropout, 300ma linear regulators in sot23 4 _______________________________________________________________________________________ 0 20 40 60 80 100 120 140 160 0 100 50 150 200 250 300 dropout voltage vs. load current max8887-8 toc04 load current (ma) v dropout (mv) t a = +25 c t a = +85 c t a = -40 c 0 50 100 150 200 250 300 2.5 2.7 2.9 3.1 3.3 dropout voltage vs. output voltage max8887-8 toc05 v out (v) v dropout (mv) i out = 200ma maximum typical 0 1.0 2.0 3.0 4.0 5.0 input voltage (v) 0 50 25 100 75 125 150 ground-pin current vs. input voltage max8887-8 toc06 ground-pin current ( a) i load = 300ma i load = 0 0 20 60 40 80 100 0100 50 150 200 250 300 ground-pin current vs. load current max8887-8 toc07 load current (ma) ground-pin current ( a) v in = +5.5v v in = +3.8v 50 56 54 52 58 60 62 64 66 68 70 -40 10 -15 35 60 85 ground-pin current vs. temperature max8887-8 toc08 temperature ( c) ground-pin current ( a) i out = 0 v in = v out + 500mv 70 0.01 0.1 1 10 100 1000 60 50 40 30 20 power-supply rejection ratio vs. frequency max8887-8 toc09 frequency (khz) psrr (db) 10 0 c out = 2.2 f c bp = 0.01 f v out = +3.30v i load = 30ma max8887 only max8887 output noise dc to 1mhz v out 50 v/div max8887-9 toc10 time (40ms/div) v out = +1.8v, v in = 3.8v, i load = 15 m a load-transient response 50mv/div ac-coupled max8887-9 toc11 300ma 10ma v out i out v out = +3.3v v in = +3.8v time (10 s/div) typical operating characteristics (continued) ( typical operating circuit , t a = +25 c, unless otherwise noted.)
max8887/max8888 low-dropout, 300ma linear regulators in sot23 _______________________________________________________________________________________ 5 line-transient response max8887-9 toc13 20mv/div ac-coupled +4v +4.5v v out v in v out = +3.3v i load = 100ma time (100 s/div) shutdown waveform max8887-9 toc14 v shdn 1v/div dc-coupled 2v/div v out v out = +3.3v, r load = 10 ? time (20 s/div) pok waveform max8887-9 toc15 2v/div 2v/div 2v/div v out v pok v in v out = +3.3v, r load = 100 ? time (20ms/div) pin description max8887 max8888 name function 11in regulator input. supply voltage can range from 2.5v to 5.5v. bypass with 2.2 f capacitor to gnd (see capacitor selection and regulator stability ). 2 2 gnd ground 33 shdn active-low shutdown input. a logic low reduces the supply current to below 0.1 a. in shutdown, pok and out are driven low. connect to in for normal operation. 4pok open-drain active-low pok output. pok remains low while the output voltage (v out ) is below the reset threshold. connect a 100k ? pullup resistor to out to obtain a logic level output. pok is driven low in shutdown. if not used, leave this pin unconnected. 4 bp reference bypass. bypass with a low-leakage 0.01 f ceramic capacitor. 5 5 out regulator output. sources up to 300ma guaranteed. bypass with 2.2 f (<0.2 ? typical esr) ceramic capacitor to gnd. load-transient response near dropout max8887-9 toc12 50mv/div ac-coupled 300ma 10ma v out i out v out = +3.3v v in = +3.4v time (10 s/div) typical operating characteristics (continued) ( typical operating circuit , t a = +25 c, unless otherwise noted.)
detailed description the max8887/max8888 are low-dropout, low-quies- cent-current linear regulators designed primarily for battery-powered applications. the devices supply loads up to 300ma and are available in several fixed output voltages in the +1.5 to +3.3v range. the max8887 is optimized for low-noise operation, while the max8888 includes an open-drain pok output flag. as illustrated in figure 1, the max8888 consists of a 1.25v reference, error amplifier, p-channel pass tran- sistor, and internal feedback voltage divider. internal p-channel pass transistor the max8887/max8888 feature a 0.5 ? p-channel mosfet pass transistor. unlike similar designs using pnp pass transistors, p-channel mosfets require no base drive, which reduces quiescent current. pnp- based regulators also waste considerable current in dropout when the pass transistor saturates and use high base drive currents under large loads. the max8887/max8888 do not suffer from these problems and consume only 55a of quiescent current under heavy loads as well as in dropout. ouput voltage selection the max8887/max8888 are supplied with various fac- tory-set output voltages ranging from 1.5v to 3.3v. the part number s two-digit suffix identifies the nominal out- put voltage. for example, the max8887euk33 has a preset output voltage of 3.3v (see ordering infor- mation ). shutdown drive shdn low to enter shutdown. during shutdown, the output is disconnected from the input and supply current drops to 0.1a. when in shutdown, pok and out are driven low. shdn can be pulled as high as 6v, regardless of the input and output voltages. power-ok output the power-ok output (pok) pulls low when out is less than 93% of the nominal regulation voltage. once out exceeds 93% of the nominal voltage, pok goes high impedance. pok is an open-drain n-channel output. to obtain a logic level output, connect a pullup resistor from pok to out. a 100k ? resistor works well for most applications. pok can be used as a power-on-reset (por) signal to a microcontroller (c) or to drive other logic. adding a capacitor from pok to ground creates pok delay. when the max8887 is shut down, pok is held low independent of the output voltage. if unused, leave pok grounded or unconnected. current limit the max8887/max8888 monitor and control the pass transistor s gate voltage, limiting the output current to 0.8a (typ). this current limit is reduced to 500ma (typ) when the output voltage is below 93% of the nominal value to provide foldback current limiting. thermal-overload protection thermal-overload protection limits total power dissipa- tion in the max8887/max8888. when the junction tem- perature exceeds t j =+170 c, a thermal sensor turns off the pass transistor, allowing the device to cool. the thermal sensor turns the pass transistor on again after the junction temperature cools by 20 c, resulting in a pulsed output during continuous thermal overload con- ditions. thermal overload protection protects the max8887/max8888 in the event of fault conditions. for continuous operation, do not exceed the absolute maxi- mum junction-temperature rating of t j =+150 c. operating region and power dissipation the max8887/max8888 s maximum power dissipation depends on the thermal resistance of the ic package and circuit board. the temperature difference between the die junction and ambient air, and the rate of air flow. the power dissipated in the device is p = i out ? (v in - v out ). the maximum allowed power dissipation is 727mw or: p max = (t j(max) - t a ) / ( jc + ca ) where t j(max) -t a is the temperature difference between the max8887/max8888 die junction and the surrounding air; jc is the thermal resistance from the junction to the case; and ca is the thermal resistance from the case through pc board, copper traces, and other materials to the surrounding air. refer to figure 2 for the max8887/max888 valid oper- ating region. noise reduction for the max8887 only, an external 0.01f bypass capacitor at bp creates a lowpass filter for noise reduc- tion. the max8887 exhibits 42v rms of output voltage noise with c bp = 0.01f and c out = 2.2f (see typical operating characteristics ) . applications information capacitor selection and regulator stability connect a 2.2f ceramic capacitor between in and ground and a 2.2f ceramic capacitor between out and ground. the input capacitor (c in ) lowers the source impedance of the input supply. reduce noise and improve load-transient response, stability, and power-supply rejection by using a larger ceramic out- put capacitor such as 4.7f. the output capacitor s (c out ) equivalent series resis- tance (esr) affects stability and output noise. use out- max8887/max8888 low-dropout, 300ma linear regulators in sot23 6 _______________________________________________________________________________________
put capacitors with an esr of 0.1 ? or less to ensure sta- bility and optimum transient response. surface-mount ceramic capacitors have very low esr and are com- monly available in values up to 10f. connect c in and c out as close to the max8887/max8888 as possible to minimize the impact of pc board trace inductance. noise, psrr, and transient response the max8887/max8888 are designed to operate with low dropout voltages and low quiescent currents in bat- tery-powered systems while still maintaining excellent noise, transient response, and ac rejection. see the typical operating characteristics for a plot of power- supply rejection ratio (psrr) versus frequency. when operating from noisy sources, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors and through passive filtering techniques. input-output (dropout) voltage a regulator s minimum input-to-output voltage differen- tial (dropout voltage) determines the lowest usable sup- ply voltage at which the output is regulated. in battery-powered systems, this determines the useful end-of-life battery voltage. the max8887/max8888 use a p-channel mosfet pass transistor. its dropout volt- age is a function of drain-to-source on-resistance (r ds(on) ) multiplied by the load current (see typical operating characteristics ). v dropout = v in - v out = r ds(on) ? i out chip information transistor count: 620 process: bicmos max8887/max8888 low-dropout, 300ma linear regulators in sot23 _______________________________________________________________________________________ 7 shutdown logic error amp 1.25v ref 95% ref p out pok gnd in shdn max8888 thermal sensor mos driver with i limit pok figure 1. functional diagram 0 100 200 300 400 0 1.0 2.0 3.0 0.5 1.5 2.5 3.5 4.0 maximum output current vs. input voltage (power dissipation limit) (v in - v out ) (v) maximum output current (ma) v out = +3.3v v out = +2.85v v out = +1.8v maximum recommended output current t a = +85 c t a = +70 c figure 2. power operating regions: maximum output current vs. input voltage
max8887/max8888 low-dropout, 300ma linear regulators in sot23 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 ? 2000 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information thin sot23.eps
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