available si91841 vishay siliconix document number: 71447 s-50956?rev. d, 16-may-05 www.vishay.com 1 150-ma ultra low-noise ldo regulator with discharge option features ultra low dropout?130 mv at 150-ma load ultra low noise?30 v (rms) (10-hz to 100-khz bandwidth) shutdown control 110- a ground current at 150-ma load 1.5% guaranteed output voltage accuracy 300-ma peak output current capability uses low esr ceramic capacitors fast start-up (50 s) fast line and load transient response ( 30 s) 1- a maximum shutdown current output current limit reverse battery protection built-in short circuit and thermal protection output, auto-discharge in shutdown mode fixed 1.8, 2.5, 2.6, 2.8, 2.85, 2.9, 3.0, 3.3, 5.0-v output voltage options thin sot23-5 package applications cellular phones, wireless handsets noise-sensitive electronic systems, laptop and palmtop computers pdas pagers digital cameras mp3 player wireless modem description the si91841 is a 150-ma cmos ldo (low dropout) voltage regulator. it is the perfect choice for low voltage, low power applications. an ultra low ground current makes this part attractive for battery operated power systems. the si91841 also offers ultra low dropout voltage to prolong battery life in portable electronics. systems requiring a quiet voltage source, such as rf applications, will benefit from the si91841?s ultra low output noise. an external noise bypass capacitor connected to the device?s bp pin can further reduce the noise level. the si91841 is designed to maintain regulation while delivering 300-ma peak current, making it ideal for systems that have a high surge current upon turn-on. for better transient response and regulation, an active pull-down circuit is built into the si91841 to clamp the output voltage when it rises beyond normal regulation. the si91841 automatically discharges the output voltage by connecting the output to ground through a 100- n-channel mosfet when the device is put in shutdown mode. the si91841 features reverse battery protection to limit reverse current flow to approximately 1- a in the event reversed battery is applied at the input, thus preventing damage to the ic. the si91841 is available in both standard and lead (pb)-free packages. typical application circuit 3 2 si91841 1 4 5 v in gnd sd v out v in sd v out 1 f 1 f bp 10 nf thin sot -23, 5-lead
si91841 vishay siliconix www.vishay.com 2 document number: 71447 s-50956?rev. d, 16-may-05 absolute maximum ratings absolute maximum ratings input voltage, v in to gnd ? 6.0 to 6.5 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v sd (see detailed description) ? 0.3 v to v in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . output current, i out short circuit protected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . output v oltage, v out ? 0.3 v to v in + 0.3 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . package power dissipation, (p d ) b 440 mw . . . . . . . . . . . . . . . . . . . . . . . . . . . package thermal resistance, ( ja ) a 180 c/w . . . . . . . . . . . . . . . . . . . . . . . . . maximum junction temperature, t j(max) 150 c . . . . . . . . . . . . . . . . . . . . . . . storage temperature, t stg ? 65 c to 150 c . . . . . . . . . . . . . . . . . . . . . . . . . . notes a. device mounted with all leads soldered or welded to pc board. b. derate 5.5 mw/ c above t a = 70 c stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratin gs only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. recommended operating range input v oltage, v in 2 v to 6 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . input voltage, v sd 0 v to v in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . operating ambient temperature, t a ? 40 c to 85 c . . . . . . . . . . . . . . . . . . . . c in = c out = 1 f (ceramic), c bp = 0.01 f (ceramic) maximum esr of c out : 0.4 specifications test conditions unless specified t a = 25 c, v in = v out(nom) + 1 v c c limits ? 40 to 85 c parameter symbol () i out = 1 ma, c in = 1 f, c out = 1.0 f v sd = 1.5 v temp a min b typ c max b unit start-up bp current i out on/off = high room 1 ma input voltage range v in full 2 6 v output voltage accuracy v out 1 ma i out 150 ma room ? 1.5 1 1.5 % output voltage accuracy v out 1 ma i out 150 ma full ? 2.5 1 2.5 % line regulation (v out 3 v) full ? 0.06 0.18 line regulation (3.0 v < v out 3.6 v) v out 100 v in v out(nom) from v in = v out(nom) + 1 v to v out(nom) + 2 v full 0 0.3 %/v line regulation (5-v v ersion) in out(nom) from v in = 5.5 v to 6 v full 0 0.4 i out = 1 ma room 1 dt vlt dg i out = 50 ma room 45 80 dropout voltage d, g ( v out(nom) 2.6 v ) i out = 50 ma full 50 90 (v out(nom) 2 . 6 v) i out = 150 ma room 130 180 v in ? v out i out = 150 ma full 220 mv in out i out = 50 ma room 65 100 dropout voltage d, g (v out( ) 26 v v in i out = 50 ma full 120 (v out(nom) 2.6 v, v in 2 v) i out = 150 ma room 190 250 2 v) i out = 150 ma full 300 i out = 0 ma room 100 150 ground pin current e, g i out = 0 ma full 180 ground pin current e, g (v out(nom) 3 v) i out = 150 ma room 110 200 i gnd i out = 150 ma full 230 a i gnd i out = 0 ma room 110 170 a ground pin current e i out = 0 ma full 200 ground pin current e (v out(nom) 3 v) i out = 150 ma room 120 200 i out = 150 ma full 230 peak output current i o(peak) v out 0.95 x v out(nom) . t pw = 2 ms full 300 ma
si91841 vishay siliconix document number: 71447 s-50956?rev. d, 16-may-05 www.vishay.com 3 specifications limits ? 40 to 85 c temp a test conditions unless specified t a = 25 c, v in = v out(nom) + 1 v i out = 1 ma, c in = 1 f, c out = 1.0 f v sd = 1.5 v parameter unit max b typ c min b temp a test conditions unless specified t a = 25 c, v in = v out(nom) + 1 v i out = 1 ma, c in = 1 f, c out = 1.0 f v sd = 1.5 v symbol output noise voltage e n v nom = 2.6 v, bw = 10 hz to 100 khz, 0 ma i out 150 ma, c noise = 0.01 f room 30 v(rms) f = 1 khz room 60 ripple rejection v out / v in i out = 150 ma f = 10 khz room 40 db pp j out in out f = 100 khz room 30 dynamic line regulation v o(line) v in : v out(nom) + 1 v to v out(nom) + 2 v t r /t f = 2 s, i out = 150 ma room 20 mv dynamic load regulation v o(load) i out : 1 ma to 150 ma, t r /t f = 2 s room 20 mv thermal shutdown junction temperature t j(s/d) room 150 c thermal hysteresis t hyst room 20 c reverse current i r v in = ? 6.0 v room 1 a short circuit current i sc v out = 0 v room 700 ma shutdown shutdown supply current i cc(off) v sd = 0 v room 0.1 1 a sd pin input voltage v sd high = regulator on (rising) full 1.5 v in v sd pin input voltage v sd low = regulator off (falling) full 0.4 v auto discharge resistance r_dis si91841 only room 100 sd pin input current f i in(sd ) v sd = 1.5 v, v in = 6 v room 0.7 a sd hysteresis v hyst(sd ) full 150 mv v out turn-on time t on v sd (see figure 1), i load = 100 na 50 s notes a. room = 25 c, full = ? 40 to 85 c. b. the algebraic convention whereby the most negative value is a minimum and the most positive a maximum. c. typical values are for design aid only, not guaranteed nor subject to production testing. typical values for dropout voltage at v out 2 v are measured at v out = 3.3 v, while typical values for dropout voltage at v out < 2 v are measured at v out = 1.8 v. d. dropout voltage is defined as the input to output differential voltage at which the output voltage drops 2% below the output voltage measured with a 1-v differential, provided that v in does not not drop below 2.0 v. e. ground current is specified for normal operation as well as ?drop-out? operation. f. the device?s shutdown pin includes a typical 2-m internal pull-down resistor connected to ground. g. v out(nom) is v out when measured with a 1-v differential to v in. timing waveforms figure 1. timing diagram for power-up v sd 0.95 v nom v out v nom t on 0 v v in t r 1 s
sd 3 2 thin sot -23, 5-lead 1 4 5 v in gnd v out bp si91841 vishay siliconix www.vishay.com 4 document number: 71447 s-50956?rev. d, 16-may-05 pin configuration pin description pin no. name function 1 v in input supply pin. bypass this pin with a 1- f ceramic or tantalum capacitor to ground 2 gnd ground pin. for better thermal capability, directly connected to large ground plane 3 sd by applying less than 0.4 v to this pin, the device will be turned off. connect this pin to v in if unused 4 bp noise bypass pin. for low noise applications, a 0.01 f ceramic capacitor should be connected from this pin to ground. 5 v out output voltage. connect c out between this pin and ground. ordering informationsi91841 part number lead (pb)-free part number marking voltage temperature range package si91841dt-18-t1 si91841dt-18-t1?e3 b4ll 1.8 si91841dt-25-t1 si91841dt-25-t1?e3 b7ll 2.5 si91841dt-26-t1 si91841dt-26-t1?e3 b8ll 2.6 SI91841DT-28-T1 SI91841DT-28-T1?e3 b0ll 2.8 si91841dt-285-t1 si91841dt-285?e3 c1ll 2.85 ? 40 to 85 c thin sot23-5 si91841dt-29-t1 si91841dt-29-t1?e3 c2ll 2.9 si91841dt-30-t1 si91841dt-30-t1?e3 c3ll 3.0 si91841dt-33-t1 si91841dt-33-t1?e3 c4ll 3.3 si91841dt-50-t1 si91841dt-50-t1?e3 c7ll 5.0 note: ll = lot code
si91841 vishay siliconix document number: 71447 s-50956?rev. d, 16-may-05 www.vishay.com 5 typical characteristics (internally regulated, 25 c unless noted) ? 1.0 ? 0.8 ? 0.6 ? 0.4 ? 0.2 ? 0.0 0.2 0.4 ? 40 ? 15 10 35 60 85 normalized v out vs. t emperature ambient temperature ( c) (%) v out 0 50 100 150 200 250 300 234567 no load gnd pin current vs. input voltage ( i gnd a) input voltage (v) i out = 0 ma i out = 150 ma i out = 75 ma ? 40 c 85 c 50 75 100 125 150 0 25 50 75 100 125 150 gnd current vs. load current ( i gnd a) load current (ma) 600 625 650 675 700 725 750 ? 40 ? 15 10 35 60 85 output short circuit current vs. t emperature 25 c (ma) i sc ambienttemperature ( c) 25 c ? 80 ? 60 ? 40 ? 20 0 10 100 1000 10000 100000 1000000 power supply rejection frequency (hz) gain (db) c in = 1 f c out = 1 f i load = 150 ma v out = 3.0 v ? 0.75 ? 0.60 ? 0.45 ? 0.30 ? 0.15 0.00 0.15 0.30 0 25 50 75 100 125 150 normalized output voltage vs. load current output voltage (%) load current (ma) v out = 2.6 v v in = v out(nom) + 1 v v out = 3.0 v v in = 4.0 v v in = v out(nom) + 1 v ? 40 c 85 c
si91841 vishay siliconix www.vishay.com 6 document number: 71447 s-50956?rev. d, 16-may-05 typical characteristics (internally regulated, 25 c unless noted) 0 50 100 150 200 250 300 350 0 60 120 180 240 300 dropout v oltage vs. load current i load (ma) (mv) v drop 0 50 100 150 200 250 300 350 ? 50 ? 25 0 25 50 75 100 125 150 dropout v oltage vs. t emperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0123456 v in ? v out transfer characteristic v in (v) (v) v out junction temperature ( c) 0 50 100 150 200 250 300 350 400 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 dropout voltage vs. v out dropout voltage (mv) v out (mv) v drop i out = 0 ma i out = 150 ma i out = 10 ma i out = 75 ma v out = 3.0 v v out = 3.0 v v out = 3.0 v i out = 10 ma i out = 75 ma i out = 150 ma i out = 300 ma i out = 300 ma
si91841 vishay siliconix document number: 71447 s-50956?rev. d, 16-may-05 www.vishay.com 7 typical waveforms load t ransient response-1 i load 100 ma/div v out 10 mv/div v out = 3.0 v c out = 1 f i load = 1 to 150 ma t rise = 2 sec load t ransient response-2 v out = 3.0 v c out = 1 f i load = 150 to 1 ma t fall = 2 sec 20 s/div i load 100 ma/div v out 10 mv/div linetransient response-1 v out 10 mv/div v in 2 v/div v instep = 4 to 5 v v out = 3 v c out = 1 f c in = 1 f i load = 150 ma t rise = 5 sec 20 s/div linetransient respons-2 v instep = 5 to 4 v v out = 3 v c out = 1 f c in = 1 f i load = 150 ma t fall = 5 sec 20 s/div 20 s/div v out 10 mv/div v in 2 v/div
si91841 vishay siliconix www.vishay.com 8 document number: 71447 s-50956?rev. d, 16-may-05 typical waveforms output noise v out 200 v/div noise spectrum 4 ms/div 10 hz v in = 4 v v out = 3 v i out = 150 ma c noise = 0.01 f bw = 10 hz to 100 khz 10 0.01 1 mhz v in = 4 v v out = 3 v i load = 150 ma c noise = 0.01 f v hz output spectral noise density block diagram si91841 v in reference ? + thermal sensor shutdown control gnd v out reverse polarity protection current limit sd bp
si91841 vishay siliconix document number: 71447 s-50956?rev. d, 16-may-05 www.vishay.com 9 detailed description the si91841 is a low-noise, low drop-out and low quiescent current linear voltage regulator, packaged in a small footprint thin sot23-5 package. the si91841 can supply loads up to 150 ma. as shown in the block diagram, the circuit consists of a bandgap reference error, amplifier, p-channel pass transistor and feedback resistor string. an external bypass capacitor connected to the bp pin reduces noise at the output. additional blocks, not shown in the block diagram, include a precise current limiter, reverse battery and current protection and thermal sensor. thermal overload protection the thermal overload protection limits the total power dissipation and protects the device from being damaged. when the junction temperature exceeds 150 , the device turns the p-channel pass transistor off. reverse battery protection the si91841 has a battery reverse protection circuitry that disconnects the internal circuitry when v in drops below the gnd voltage. there is no current drawn in such an event. when the sd pin is hardwired to v in , the user must connect the sd pin to v in via a 100-k resistor if reverse battery protection is d esired. hardwiring the sd pin directly to the v in pin is allowed when reverse battery protection is not desired. noise reduction an external 10-nf bypass capacitor at bp is used to create a low pass filter for noise reduction. the start-up time is fast, since a power-on circuit pre-charges the bypass capacitor. after the power-up sequence the pre-charge circuit is switched to standby mode in order to save current. it is therefore not recommended to use larger bypass capacitor values than 50 nf. when the circuit is used without a capacitor, stable operation is guaranteed. auto-discharge/no-discharge for si91841 only, v out has an internal 100- (typ.) discharge path to ground when the sd pin is low. stability the circuit is stable with only a small output capacitor equal to 6 nf/ma (= 1 f @ 150 ma). since the bandwidth of the error amplifier is around 1 ? 3 mhz and the dominant pole is at the output node, the capacitor should be capacitive in this range, i.e., for 150-ma load current, an esr <0.4 is necessary. parasitic inductance of about 10 nh can be tolerated. vishay siliconix maintains worldwide manufacturing c apability. pr oducts may be manufactured at on e of several qualified locati ons. reliability data for silicon technology and package reliability repr esent a composite of all qualified locations. for re lated documents such as package/tape drawings, par t marking, and reliability data, see http://www.vishay.com/ppg?71447 .
document number: 91000 www.vishay.com revision: 18-jul-08 1 disclaimer legal disclaimer notice vishay all product specifications and data are subject to change without notice. vishay intertechnology, inc., its affiliates, agents, and employees, and all persons acting on its or their behalf (collectively, ?vishay?), disclaim any and all liability fo r any errors, inaccuracies or incompleteness contained herein or in any other disclosure relating to any product. vishay disclaims any and all li ability arising out of the use or application of any product describ ed herein or of any information provided herein to the maximum extent permit ted by law. the product specifications do not expand or otherwise modify vishay?s terms and conditions of purcha se, including but not limited to the warranty expressed therein, which apply to these products. no license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document or by any conduct of vishay. the products shown herein are not designed for use in medi cal, life-saving, or life-sustaining applications unless otherwise expressly indicated. customers using or selling vishay products not expressly indicated for use in such applications do so entirely at their own risk and agree to fully indemnify vishay for any damages arising or resulting from such use or sale. please contact authorized vishay personnel to obtain written terms and conditions regarding products designed for such applications. product names and markings noted herein may be trademarks of their respective owners.
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