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features description/ordering information LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 wide input range ? up to 30 v stable with low esr (>12 m w ) capacitors rated output current of 100 ma current- and thermal-limiting features low dropout ? 380 mv (typ) at 100 ma LP2950 only (3-pin package) low quiescent current ? 75 m a (typ) ? fixed-output voltages of 5 v, 3.3 v, and 3 v tight line regulation ? 0.03% (typ) lp2951 only (8-pin package) tight load regulation ? 0.04% (typ) ? fixed- or adjustable-output voltages: high v o accuracy 5 v/adj, 3.3 v/adj, and 3 v/adj ? 1.4% at 25 c ? low-voltage error signal on falling output ? 2% over temperature ? shutdown capability can be used as a regulator or reference ? remote sense capability for optimal output regulation and accuracy the LP2950 and lp2951 devices are bipolar, low-dropout voltage regulators that can accommodate a wide input supply-voltage range of up to 30 v. the easy-to-use, 3-pin LP2950 is available in fixed-output voltages of 5 v, 3.3 v, and 3 v. however, the 8-pin lp2951 is able to output either a fixed or adjustable output from the same device. by tying the output and sense pins together, and the feedback and v tap pins together, the lp2951 outputs a fixed 5 v, 3.3 v, or 3 v (depending on the version). alternatively, by leaving the sense and v tap pins open and connecting feedback to an external resistor divider, the output can be set to any value between 1.235 v to 30 v. the 8-pin lp2951 also offers additional functionality that makes it particularly suitable for battery-powered applications. for example, a logic-compatible shutdown feature allows the regulator to be put in standby mode for power savings. in addition, there is a built-in supervisor reset function in which the error output goes low when v out drops by 6% of its nominal value for whatever reasons ? due to a drop in v in , current limiting, or thermal shutdown. the LP2950 and lp2951 are designed to minimize all error contributions to the output voltage. with a tight output tolerance (0.5% at 25 c), a very low output voltage temperature coefficient (20 ppm typical), extremely good line and load regulation (0.3% and 0.4% typical), and remote sensing capability, the parts can be used as either low-power voltage references or 100-ma regulators. please be aware that an important notice concerning availability, standard warranty, and use in critical applications of texas instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. production data information is current as of publication date. copyright ? 2006?2007, texas instruments incorporated products conform to specifications per the terms of the texas instruments standard warranty. production processing does not necessarily include testing of all parameters. www.ti.com outputgnd input 12 3 4 87 6 5 input feedback v tap error output sense shutdown gnd lp2951...d (soic) package (top view) LP2950...lp (to-226/to-92 package (bottom view)
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 ordering information (1) v out orderable t a package (2) top-side marking (nom) part number bulk of 1000 LP2950-30lp to-226/to-92 ? lp ky5030 reel of 2000 LP2950-30lpr 3 v tube of 75 lp2951-30d soic ? d ky5130 reel of 2500 lp2951-30dr bulk of 1000 LP2950-33lp to-226/to-92 ? lp ky5033 reel of 2000 LP2950-33lpr 3.3 v tube of 75 lp2951-33d ?40 c to 125 c soic ? d ky5133 reel of 2500 lp2951-33dr bulk of 1000 LP2950-50lp preview to-226/to-92 ? lp reel of 2000 LP2950-50lpr ky5050 5 v tube of 75 lp2951-50d soic ? d ky5150 reel of 2500 lp2951-50dr tube of 75 lp2951d adj soic-d ky5150 reel of 2500 lp2951dr (1) for the most current package and ordering information, see the package option addendum at the end of this document, or see the ti website at www.ti.com . (2) package drawings, standard packing quantities, thermal data, symbolization, and pcb design guidelines are available at www.ti.com/sc/package . 2 submit documentation feedback www.ti.com
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 LP2950 functional block diagram lp2951 functional block diagram 3 submit documentation feedback www.ti.com v out i l 100 ma error amplifier ? + 1.23-vreference input output gnd + + unregulated dc + see application information t o cmos or ttl v out i l 100 ma error amplifier ? + 1.235-vreference input sense gnd + + + unregulated dc feedback ? + v tap error shutdown + 330 k error detection comparator 4 5 6 2 output 1 8 7 3 from cmos or ttl 60 mv see application information see application information
absolute maximum ratings (1) recommended operating conditions LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 over operating free-air temperature range (unless otherwise noted) min max unit v in continuous input voltage range ?0.3 30 v v shdn shutdown input voltage range ?1.5 30 v error comparator output voltage range (2) ?1.5 30 v v fdbk feedback input voltage range (2) (3) ?1.5 30 v d package 97 q ja package thermal impedance (4) (5) c/w lp package 140 t j operating virtual junction temperature 150 c t stg storage temperature range ?65 150 c (1) stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. (2) may exceed input supply voltage (3) if load is returned to a negative power supply, the output must be diode clamped to gnd. (4) maximum power dissipation is a function of t j (max), q ja , and t a . the maximum allowable power dissipation at any allowable ambient temperature is p d = (t j (max) ? t a )/ q ja . operating at the absolute maximum t j of 150 c can affect reliability. (5) the package thermal impedance is calculated in accordance with jesd 51-7. min max unit v in supply input voltage (1) 30 v t j operating virtual junction temperature ?40 125 c (1) minimum v in is the greater of: a. 2 v (25 c), 2.3 v (over temperature), or b. v out(max) + dropout (max) at rated i l 4 submit documentation feedback www.ti.com
electrical characteristics LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 v in = v out (nominal) + 1 v, i l = 100 m a, c l = 1 m f (5-v versions) or c l = 2.2 m f (3-v and 3.3-v versions), 8-pin version: feedback tied to v tap , output tied to sense, v shutdown 0.7 v parameter test conditions t j min typ max unit 3-v version (lp295x-30) 25 c 2.970 3 3.030 v out output voltage i l = 100 m a v ?40 c to 125 c 2.940 3 3.060 3.3-v version (lp295x-33) 25 c 3.267 3.3 3.333 v out output voltage i l = 100 m a v ?40 c to 125 c 3.234 3.3 3.366 5-v version (lp295x-50) 25 c 4.950 5 5.050 v out output voltage i l = 100 m a v ?40 c to 125 c 4.900 5 5.100 all voltage options output voltage temperature i l = 100 m a ?40 c to 125 c 20 100 ppm/ c coefficient (1) 25 c 0.03 0.2 line regulation (2) v in = [v out(nom) + 1 v] to 30 v %/v ?40 c to 125 c 0.4 25 c 0.04 0.2 load regulation (2) i l = 100 m a to 100 ma % ?40 c to 125 c 0.3 25 c 50 80 i l = 100 m a ?40 c to 125 c 150 v in ? v out dropout voltage (3) mv 25 c 380 450 i l = 100 ma ?40 c to 125 c 600 25 c 75 120 i l = 100 m a m a ?40 c to 125 c 140 i gnd gnd current 25 c 8 12 i l = 100 ma ma ?40 c to 125 c 14 25 c 110 170 v in = v out(nom) ? 0.5 v, dropout ground current m a i l = 100 m a ?40 c to 125 c 200 25 c 160 200 current limit v out = 0 v ma ?40 c to 125 c 220 thermal regulation (4) i l = 100 m a 25 c 0.05 0.2 %/w c l = 1 m f (5 v only) 430 c l = 200 m f 160 output noise (rms), 25 c m v lp2951-50: c l = 3.3 m f, 10 hz to 100 khz c bypass = 0.01 m f between pins 1 100 and 7 (lp2951-xx) 8-pin version only adj 25 c 1.218 1.235 1.252 ?40 c to 125 c 1.212 1.257 reference voltage v v out = v ref to (v in ? 1 v), v in = 2.3 v to 30 v, ?40 c to 125 c 1.200 1.272 i l = 100 m a to 100 ma reference voltage 25 c 20 ppm/ c temperature coefficient (1) (1) output or reference voltage temperature coefficient is defined as the worst-case voltage change divided by the total temperature range. (2) regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. changes in output voltage due to heating effects are covered under the specification for thermal regulation. (3) dropout voltage is defined as the input-to-output differential at which the output voltage drops 100 mv, below the value measured at 1-v differential. the minimum input supply voltage of 2 v (2.3 v over temperature) must be observed. (4) 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 50-ma load pulse at v in = 30 v, v out = 5 v (1.25-w pulse) for t = 10 ms. 5 submit documentation feedback www.ti.com
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 electrical characteristics (continued) v in = v out (nominal) + 1 v, i l = 100 m a, c l = 1 m f (5-v versions) or c l = 2.2 m f (3-v and 3.3-v versions), 8-pin version: feedback tied to v tap , output tied to sense, v shutdown 0.7 v parameter test conditions t j min typ max unit 25 c 20 40 feedback bias current na ?40 c to 125 c 60 feedback bias current 25 c 0.1 na/ c temperature coefficient error comparator 25 c 0.01 1 output leakage current v out = 30 v m a ?40 c to 125 c 2 25 c 150 250 v in = v out(nom) ? 0.5 v, output low voltage mv i ol = 400 m a ?40 c to 125 c 400 25 c 40 60 upper threshold voltage mv ( error output high) (5) ?40 c to 125 c 25 25 c 75 95 lower threshold voltage mv ( error output low) (5) ?40 c to 125 c 140 hysteresis (6) 25 c 15 mv shutdown input low (regulator on) 0.7 input logic voltage ?40 c to 125 c v high (regulator off) 2 25 c 30 50 v tap = 2.4 v ?40 c to 125 c 100 shutdown input current m a 25 c 450 600 v tap = 30 v ?40 c to 125 c 750 v shutdown 3 2 v, 25 c 3 10 regulator output current v in 30 v, v out = 0, m a in shutdown ?40 c to 125 c 20 feedback tied to v tap (5) comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured at v in ? v out = 1 v) minus feedback terminal voltage. to express these thresholds in terms of output voltage change, multiply by the error amplifier gain = v out /v ref = (r1 + r2)/r2. for example, at a programmed output voltage of 5 v, the error output is specified to go low when the output drops by 95 mv 5 v/1.235 v = 384 mv. thresholds remain constant as a percentage of v out (as v out is varied), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max). (6) comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured at v in ? v out = 1 v) minus feedback terminal voltage. to express these thresholds in terms of output voltage change, multiply by the error amplifier gain = v out /v ref = (r1 + r2)/r2. for example, at a programmed output voltage of 5 v, the error output is specified to go low when the output drops by 95 mv 5 v/1.235 v = 384 mv. thresholds remain constant as a percentage of v out (as v out is varied), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max). 6 submit documentation feedback www.ti.com
typical characteristics LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 quiescent current input current vs vs load current input voltage input current input current vs vs input voltage input voltage 7 submit documentation feedback www.ti.com 0.01 0.1 1 10 0.0001 0.001 0.01 0.1 i l C load current C a quiescent current C ma 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 v in C input voltage C v input current C a r = l 0 20 40 60 80 100 120 140 160 180 200 0 1 2 3 4 5 6 7 8 9 10 v in C input voltage C v input current C a r = 50 k l 0 10 20 30 40 50 60 70 80 90 100 110 120 0 1 2 3 4 5 6 7 8 9 10 v in C input voltage C v input current C ma r = 50 l
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) output voltage quiescent current vs vs temperature input voltage quiescent current quiescent current vs vs input voltage input voltage 8 submit documentation feedback www.ti.com 4.900 4.925 4.950 4.975 5.000 5.025 5.050 5.075 5.100 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c v out C output voltage C v i l = 100 a i l = 100 m a 0 10 20 30 40 50 60 70 80 90 100 110 120 0 1 2 3 4 5 6 7 8 v in C input voltage C v quiescent current C a i l = 0 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 v in C input voltage C v quiescent current C a i l = 100 ma 0 10 20 30 40 50 60 70 80 90 100 110 120 0 1 2 3 4 5 6 7 8 v in C input voltage C v quiescent current C a i l = 1 ma
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) quiescent current quiescent current vs vs temperature temperature short-circuit current dropout voltage vs vs temperature temperature 9 submit documentation feedback www.ti.com 50 55 60 65 70 75 80 85 90 95 100 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c quiescent current C a i l = 100 a v in = 6 v 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c quiescent current C ma i l = 100 m a v in = 6 v 50 75 100 125 150 175 200 225 250 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C tem perature C c short-circuit current C a 0 50 100 150 200 250 300 350 400 450 500 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c (v in C v out ) C dropout voltage C mv r l = 100 a r l = 100 m a
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) dropout voltage lp2951 minimum operating voltage vs vs output current temperature lp2951 feedback bias current lp2951 error comparator output vs vs temperature input voltage 10 submit documentation feedback www.ti.com 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c minimum operating voltage C v 0 50 100 150 200 250 300 350 400 0.0001 0.001 0.01 0.1 i o ? output current ? a (v in ? v out ) ? dropout voltage ? mv 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 v in C input voltage C v error output C v 50-k resistor to external 5-v supply w 50-k resistor to v w out -20 -15 -10 -5 0 5 10 15 20 25 30 -55 -30 -5 20 45 70 95 120 145 t a C temperature C c feedback bias current C na
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) lp2951 error comparator sink current line transient response vs vs output low voltage time load transient response load transient response vs vs time time (v out = 5 v, c l = 1 m f) (v out = 5 v, c l = 10 m f) 11 submit documentation feedback www.ti.com input voltage 2 v/div output voltage 80 mv/div 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 v ol ? output low voltage ? v i sink ? sink current ? ma t = 125 a t = 25 a t = ?40 a output load 100 ma/div output voltage 100 mv/div output load 100 ma/div output voltage 100 mv/div
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) enable transient response enable transient response vs vs time time (c l = 1 m f, i l = 1 ma) (c l = 10 m f, i l = 1 ma) output impedance ripple rejection vs vs frequency frequency 12 submit documentation feedback www.ti.com 20 30 40 50 60 70 80 90 1.e+01 1.e+02 1.e+03 1.e+04 1.e+05 1.e+06 f C frequency C hz power-supply ripple rejection C db i l = 100 a i l = 0 v in = 6 v c l = 1 f 10 100 1k 10k 100k 1m 0.01 0.1 1 10 100 1.e+01 1.e+02 1.e+03 1.e+04 1.e+05 1.e+06 f C frequency C hz output impedance C ohm i l = 1 m a i l = 100 m a i l = 100 a 10 100 1k 10k 100k 1m
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) ripple rejection ripple rejection vs vs frequency frequency lp2951 output noise lp2951 divider resistance vs vs frequency temperature 13 submit documentation feedback www.ti.com 10 20 30 40 50 60 70 80 90 100 1.e+01 1.e+02 1.e+03 1.e+04 1.e+05 1.e+06 f C frequency C hz power-supply ripple rejection C db i l = 10 ma i l = 1 ma v in = 6 v c l = 1 f 10 100 1k 10k 100k 1m 10 20 30 40 50 60 70 80 90 100 1.e+01 1.e+02 1.e+03 1.e+04 1.e+05 1.e+06 f C frequency C hz power-supply ripple rejection C db i l = 100 ma i l = 50 ma v in = 6 v c l = 1 f 10 100 1k 10k 100k 1m 0 50 100 150 200 250 300 350 400 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a ? temperature ? c r p2p4 ? pin 2 to pin 4 resistance ? k k w 0 1 2 3 4 5 6 1.e+01 1.e+02 1.e+03 1.e+04 1.e+05 f C frequency C hz output noise C v c l = 1 f c l = 3.3 f c l = 200 f 10 100 1k 10k 100k
LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 typical characteristics (continued) shutdown threshold voltage (off to on) shutdown threshold voltage (on to off) vs vs temperature temperature line regulation vs input voltage 14 submit documentation feedback www.ti.com 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c input logic voltage (off to on) C v 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 -40 -25 -10 5 20 35 50 65 80 95 110 125 t a C temperature C c input logic voltage (on to off) C v -2 -1 0 1 2 3 4 5 6 0 5 10 15 20 25 30 v in C input voltage C v output voltage change C mv
application information input capacitor (c in ) output capacitor (c out ) capacitance value esr range LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 a 1- m f (tantalum, ceramic, or aluminum) electrolytic capacitor should be placed locally at the input of the LP2950 or lp2951 if there is, or will be, significant impedance between the ac filter capacitor and the input; for example, if a battery is used as the input or if the ac filter capacitor is located more than 10 in away. there are no esr requirements for this capacitor, and the capacitance can be increased without limit. as with most pnp ldos, stability conditions require the output capacitor to have a minimum capacitance and an esr that falls within a certain range. for v out 3 5 v, a minimum of 1 m f is required. for lower v out , the regulator?s loop gain is running closer to unity gain and, thus, has lower phase margins. consequently, a larger capacitance is needed for stability. for v out = 3 v or 3.3 v, a minimum of 2.2 m f is recommended. for worst case, v out = 1.23 v (using the adj version), a minimum of 3.3 m f is recommended. c out can be increased without limit and only improves the regulator stability and transient response. regardless of its value, the output capacitor should have a resonant frequency less than 500 khz. the minimum capacitance values given above are for maximum load current of 100 ma. if the maximum expected load current is less than 100 ma, then lower values of c out can be used. for instance, if i out < 10 ma, then only 0.33 m f is required for c out . for i out < 1 ma, 0.1 m f is sufficient for stability requirements. thus, for a worst-case condition of 100-ma load and v out = v ref = 1.235 v (representing the highest load current and lowest loop gain), a minimum c out of 3.3 m f is recommended. for the LP2950, no load stability is inherent in the design ? a desirable feature in cmos circuits that are put in standby (such as ram keep-alive applications). if the lp2951 is used with external resistors to set the output voltage, a minimum load current of 1 m a is recommended through the resistor divider. the regulator control loop relies on the esr of the output capacitor to provide a zero to add sufficient phase margin to ensure unconditional regulator stability; this requires the closed-loop gain to intersect the open-loop response in a region where the open-loop gain rolls off at 20 db/decade. this ensures that the phase always is less than 180 (phase margin greater than 0 ) at unity gain. thus, a minimum-maximum range for the esr must be observed. the upper limit of this esr range is established by the fact that too high an esr could result in the zero occurring too soon, causing the gain to roll off too slowly, which, in turn allows a third pole to appear before unity gain and introduce enough phase shift to cause instability. this typically limits the max esr to approximately 5 w . conversely, the lower limit of the esr is tied to the fact that too low an esr shifts the zero too far out (past unity gain) and, thus, allows the gain to roll off at 40 db/decade at unity gain, with a resulting phase shift of greater than 180 . typically, this limits the minimum esr to approximately 20 m w to 30 m w . for specific esr requirements, see typical characteristics. 15 submit documentation feedback www.ti.com
capacitor types c bypass : noise and stability improvement (1) error function (lp2951 only) LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 application information (continued) most tantalum or aluminum electrolytics are suitable for use at the input. film-type capacitors also work, but at higher cost. when operating at low temperature, care should be taken with aluminum electrolytics, as their electrolytes often freeze at ?30 c. for this reason, solid tantalum capacitors should be used at temperatures below ?25 c. ceramic capacitors can be used, but due to their low esr (as low as 5 m w to 10 m w ), they may not meet the minimum esr requirement previously discussed. if a ceramic capacitor is used, a series resistor between 0.1 w to 2 w must be added to meet the minimum esr requirement. in addition, ceramic capacitors have one glaring disadvantage that must be taken into account ? a poor temperature coefficient, where the capacitance can vary significantly with temperature. for instance, a large-value ceramic capacitor ( 3 2.2 m f) can lose more than half of its capacitance as temperature rises from 25 c to 85 c. thus, a 2.2- m f capacitor at 25 c drops well below the minimum c out required for stability as ambient temperature rises. for this reason, select an output capacitor that maintains the minimum 2.2- m f required for stability for the entire operating temperature range. in the lp2951, an external feedback pin directly connected to the error amplifier noninverting input can allow stray capacitance to cause instability by shunting the error amplifier feedback to gnd, especially at high frequencies. this is worsened if high-value external resistors are used to set the output voltage, because a high resistance allows the stray capacitance to play a more significant role; i.e., a larger rc time delay is introduced between the output of the error amplifier and its feedback input, leading to more phase shift and lower phase margin. a solution is to add a 100-pf bypass capacitor (c bypass ) between output and feedback; because c bypass is in parallel with r1, it lowers the impedance seen at feedback at high frequencies, in effect offsetting the effect of the parasitic capacitance by providing more feedback at higher frequencies. more feedback forces the error amplifier to work at a lower loop gain, so c out should be increased to a minimum of 3.3 m f to improve the regulator?s phase margin. c bypass can be also used to reduce output noise in the lp2951. this bypass capacitor reduces the closed loop gain of the error amplifier at the high frequency, so noise no longer scales with the output voltage. this improvement is more noticeable with higher output voltages, because loop gain reduction is greatest. a suitable c bypass is calculated as shown in equation 1 : on the 3-pin LP2950, noise reduction can be achieved by increasing the output capacitor, which causes the regulator bandwidth to be reduced, therefore, eliminating high-frequency noise. however, this method is relatively inefficient, as increasing c out from 1 m f to 220 m f only reduces the regulator?s output noise from 430 m v to 160 m v (over a 100-khz bandwidth). the lp2951 has a low-voltage detection comparator that outputs a logic low when the output voltage drops by ? 6% from its nominal value, and outputs a logic high when v out has reached ? 95% of its nominal value. this 95% of nominal figure is obtained by dividing the built-in offset of ? 60 mv by the 1.235-v bandgap reference, and remains independent of the programmed output voltage. for example, the trip-point threshold ( error output goes high) typically is 4.75 v for a 5-v output and 11.4 v for a 12-v output. typically, there is a hysteresis of 15 mv between the thresholds for high and low error output. a timing diagram is shown in figure 1 for error vs v out (5 v), as v in is ramped up and down. error becomes valid (low) when v in ? 1.3 v. when v in ? 5 v, v out = 4.75 v, causing error to go high. because the dropout voltage is load dependent, the output trip-point threshold is reached at different values of v in , depending on the load current. for instance, at higher load current, error goes high at a slightly higher value of v in , and vice versa for lower load current. the output-voltage trip point remains at ? 4.75 v, regardless of the load. note that when v in 1.3 v, the error comparator output is turned off and pulled high to its pullup voltage. if v out is used as the pullup voltage, rather than an external 5-v source, error typically is ? 1.2 v. in this condition, an equal resistor divider (10 k w is suitable) can be tied to error to divide down the voltage to a valid logic low during any fault condition, while still enabling a logic high during normal operation. 16 submit documentation feedback www.ti.com f (cbypass) 200 hz c bypass 1 2 r1 200 hz
programming output voltage (lp2951 only) (2) LP2950 , , lp2951 adjustable micropower voltage regulators with shutdown slvs582d ? april 2006 ? revised march 2007 application information (continued) figure 1. error output timing because the error comparator has an open-collector output, an external pullup resistor is required to pull the output up to v out or another supply voltage (up to 30 v). the output of the comparator is rated to sink up to 400 m a. a suitable range of values for the pullup resistor is from 100 k w to 1 m w . if error is not used, it can be left open. a unique feature of the lp2951 is its ability to output either a fixed voltage or an adjustable voltage, depending on the external pin connections. to output the internally programmed fixed voltage, tie the sense pin to the output pin and the feedback pin to the v tap pin. alternatively, a user-programmable voltage ranging from the internal 1.235-v reference to a 30-v max can be set by using an external resistor divider pair. the resistor divider is tied to v out , and the divided-down voltage is tied directly to feedback for comparison against the internal 1.235-v reference. to satisfy the steady-state condition in which its two inputs are equal, the error amplifier drives the output to equal equation 2 : where: v ref = 1.235 v applied across r2 i fb = feedback bias current, typically 20 na a minimum regulator output current of 1 m a must be maintained. thus, in an application where a no-load condition is expected (for example, cmos circuits in standby), this 1- m a minimum current must be provided by the resistor pair, effectively imposing a maximum value of r2 = 1.2 m w (1.235 v/1.2 m w ? 1 m a). i fb = 20 na introduces an error of ? 0.02% in v out . this can be offset by trimming r1. alternatively, increasing the divider current makes i fb less significant, thus, reducing its error contribution. for instance, using r2 = 100 k w reduces the error contribution of i fb to 0.17% by increasing the divider current to ? 12 m a. this increase in the divider current still is small compared to the 600- m a typical quiescent current of the lp2951 under no load. 17 submit documentation feedback www.ti.com 5 v 1.3 v input voltage output voltage error 4.75 v v out v ref 1 r1 r2 i fb r 1
packaging information orderable device status (1) package type package drawing pins package qty eco plan (2) lead/ball finish msl peak temp (3) LP2950-30lp active to-92 lp 3 1000 pb-free (rohs) cu sn n / a for pkg type LP2950-30lpr active to-92 lp 3 2000 pb-free (rohs) cu sn n / a for pkg type LP2950-33lpe3 active to-92 lp 3 1000 pb-free (rohs) cu sn n / a for pkg type LP2950-33lpre3 active to-92 lp 3 2000 pb-free (rohs) cu sn n / a for pkg type LP2950-50lpre3 active to-92 lp 3 2000 pb-free (rohs) cu sn n / a for pkg type lp2951-30d active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-30dg4 active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-30dr active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-30drg4 active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-33d active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-33dg4 active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-33dr active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-33drg4 active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-50d active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-50dg4 active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-50dr active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951-50drg4 active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951d active soic d 8 75 green (rohs & no sb/br) cu nipdau level-1-260c-unlim lp2951dr active soic d 8 2500 green (rohs & no sb/br) cu nipdau level-1-260c-unlim (1) the marketing status values are defined as follows: active: product device recommended for new designs. lifebuy: ti has announced that the device will be discontinued, and a lifetime-buy period is in effect. nrnd: not recommended for new designs. device is in production to support existing customers, but ti does not recommend using this part in a new design. preview: device has been announced but is not in production. samples may or may not be available. obsolete: ti has discontinued the production of the device. (2) eco plan - the planned eco-friendly classification: pb-free (rohs), pb-free (rohs exempt), or green (rohs & no sb/br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. tbd: the pb-free/green conversion plan has not been defined. pb-free (rohs): ti's terms "lead-free" or "pb-free" mean semiconductor products that are compatible with the current rohs requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. where designed to be soldered package option addendum www.ti.com 11-jun-2007 addendum-page 1
at high temperatures, ti pb-free products are suitable for use in specified lead-free processes. pb-free (rohs exempt): this component has a rohs exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. the component is otherwise considered pb-free (rohs compatible) as defined above. green (rohs & no sb/br): ti defines "green" to mean pb-free (rohs compatible), and free of bromine (br) and antimony (sb) based flame retardants (br or sb do not exceed 0.1% by weight in homogeneous material) (3) msl, peak temp. -- the moisture sensitivity level rating according to the jedec industry standard classifications, and peak solder temperature. important information and disclaimer: the information provided on this page represents ti's knowledge and belief as of the date that it is provided. ti bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. efforts are underway to better integrate information from third parties. ti has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ti and ti suppliers consider certain information to be proprietary, and thus cas numbers and other limited information may not be available for release. in no event shall ti's liability arising out of such information exceed the total purchase price of the ti part(s) at issue in this document sold by ti to customer on an annual basis. package option addendum www.ti.com 11-jun-2007 addendum-page 2
tape and reel information package materials information www.ti.com 16-jun-2007 pack materials-page 1
device package pins site reel diameter (mm) reel width (mm) a0 (mm) b0 (mm) k0 (mm) p1 (mm) w (mm) pin1 quadrant lp2951-30dr d 8 fmx 330 12 6.4 5.2 2.1 8 12 q1 lp2951-33dr d 8 fmx 330 12 6.4 5.2 2.1 8 12 q1 lp2951-50dr d 8 fmx 330 12 6.4 5.2 2.1 8 12 q1 lp2951dr d 8 fmx 330 12 6.4 5.2 2.1 8 12 q1 tape and reel box information device package pins site length (mm) width (mm) height (mm) lp2951-30dr d 8 fmx 342.9 336.6 20.64 lp2951-33dr d 8 fmx 342.9 336.6 20.64 lp2951-50dr d 8 fmx 342.9 336.6 20.64 lp2951dr d 8 fmx 342.9 336.6 20.64 package materials information www.ti.com 16-jun-2007 pack materials-page 2
package materials information www.ti.com 16-jun-2007 pack materials-page 3

mechanical data msot002a ? october 1994 ? revised november 2001 1 post office box 655303 ? dallas, texas 75265 lp (o-pbcy-w3) plastic cylindrical package 4040001-2 /c 10/01 straight lead option 0.016 (0,41) 0.014 (0,35) 0.157 (4,00) max formed lead option 0.104 (2,65) 0.210 (5,34) 0.170 (4,32) 0.050 (1,27) 0.016 (0,41) 0.022 (0,56) 0.500 (12,70) min seating plane 0.175 (4,44) 0.205 (5,21) 0.165 (4,19) 0.125 (3,17) dia d c 0.105 (2,67) 0.095 (2,41) 0.135 (3,43) min 0.080 (2,03) 0.055 (1,40) 0.045 (1,14) 1 0.105 (2,67) 23 0.080 (2,03) 0.105 (2,67) notes: a. all linear dimensions are in inches (millimeters). b. this drawing is subject to change without notice. c. lead dimensions are not controlled within this area d. falls within jedec to -226 variation aa (to-226 replaces to-92) e. shipping method: straight lead option available in bulk pack only. formed lead option available in tape & reel or ammo pack.
mechanical data msot002a ? october 1994 ? revised november 2001 2 post office box 655303 ? dallas, texas 75265 lp (o-pbcy-w3) plastic cylindrical package 4040001-3 /c 10/01 0.094 (2,40) 0.114 (2,90) 0.460 (11,70) 0.539 (13,70) tape & reel 0.335 (8,50) 0.384 (9,75) 0.020 (0,50) min 0.217 (5,50) 0.748 (19,00) 0.748 (19,00) 0.689 (17,50) 0.098 (2,50) 0.433 (11,00) 0.335 (8,50) 0.610 (15,50) 0.650 (16,50) 1.260 (32,00) 0.905 (23,00) 0.234 (5,95) 0.266 (6,75) 0.512 (13,00) 0.488 (12,40) 0.114 (2,90) 0.094 (2,40) 0.146 (3,70) 0.169 (4,30) dia notes: a. all linear dimensions are in inches (millimeters). b. this drawing is subject to change without notice. c. tape and reel information for the format lead option package.
important notice texas instruments incorporated and its subsidiaries (ti) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. all products are sold subject to ti?s terms and conditions of sale supplied at the time of order acknowledgment. ti warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with ti?s standard warranty. testing and other quality control techniques are used to the extent ti deems necessary to support this warranty. except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. ti assumes no liability for applications assistance or customer product design. customers are responsible for their products and applications using ti components. to minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. ti does not warrant or represent that any license, either express or implied, is granted under any ti patent right, copyright, mask work right, or other ti intellectual property right relating to any combination, machine, or process in which ti products or services are used. information published by ti regarding third-party products or services does not constitute a license from ti to use such products or services or a warranty or endorsement thereof. use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from ti under the patents or other intellectual property of ti. reproduction of ti information in ti data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. reproduction of this information with alteration is an unfair and deceptive business practice. ti is not responsible or liable for such altered documentation. information of third parties may be subject to additional restrictions. resale of ti products or services with statements different from or beyond the parameters stated by ti for that product or service voids all express and any implied warranties for the associated ti product or service and is an unfair and deceptive business practice. ti is not responsible or liable for any such statements. ti products are not authorized for use in safety-critical applications (such as life support) where a failure of the ti product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of ti products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by ti. further, buyers must fully indemnify ti and its representatives against any damages arising out of the use of ti products in such safety-critical applications. ti products are neither designed nor intended for use in military/aerospace applications or environments unless the ti products are specifically designated by ti as military-grade or "enhanced plastic." only products designated by ti as military-grade meet military specifications. buyers acknowledge and agree that any such use of ti products which ti has not designated as military-grade is solely at the buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. ti products are neither designed nor intended for use in automotive applications or environments unless the specific ti products are designated by ti as compliant with iso/ts 16949 requirements. buyers acknowledge and agree that, if they use any non-designated products in automotive applications, ti will not be responsible for any failure to meet such requirements. following are urls where you can obtain information on other texas instruments products and application solutions: products applications amplifiers amplifier.ti.com audio www.ti.com/audio data converters dataconverter.ti.com automotive www.ti.com/automotive dsp dsp.ti.com broadband www.ti.com/broadband interface interface.ti.com digital control www.ti.com/digitalcontrol logic logic.ti.com military www.ti.com/military power mgmt power.ti.com optical networking www.ti.com/opticalnetwork microcontrollers microcontroller.ti.com security www.ti.com/security rfid www.ti-rfid.com telephony www.ti.com/telephony low power www.ti.com/lpw video & imaging www.ti.com/video wireless wireless www.ti.com/wireless mailing address: texas instruments, post office box 655303, dallas, texas 75265 copyright ? 2007, texas instruments incorporated

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