1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 1 - htc sot-223 3l pkg to-252 3l pkg ordering information device package tj3940s-x.x sot-223 3l tj3940grs-x.x to-252 3l features z ultra low dropout voltage z low ground pin current z excellent line and load regulation z guaranteed output current of 1a z available in sot-223, to-252 package z fixed output voltages : 1.2v, 1.5v, 1.8v, 2.5v, and 3.3v z over-temperature/over-current protection z -40 to 125 junction temperature range z moisture sensitivity level 3 application z battery powered equipments z motherboards and graphic cards z microprocessor power supplies z peripheral cards z high efficiency linear regulators z battery chargers x.x = output voltage = 1.2, 1.5, 1.8, 2.5, and 3.3 descripsion the tj3940 series of high performance ultra low-dropout linear regulators operates fr om 2.5v to 6v input suppl y and provides ultra low-dropout voltage, high output current with low ground current. wide range of preset output voltage options are available. these ultra low dropout linear regulators respond fast to step changes in load which makes them suitable for low voltage micro-processor applications. the tj3940 is developed on a cmos process technology which allows low quiescent current operati on independent of output load current. this cmos process also allows the tj3940 to operate under extremely low dropout conditions. absolute maximum ratings characteristic symbol min. max. unit input supply voltage (survival) v in -0.3 6.5 v maximum output current i max - 1.0 a lead temperature (soldering, 5 sec) t sol 260 storage temperature range t stg -65 150 operating junction temperature range t jopr -40 125
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 2 - htc ordering information v out package order no. description supplied as status sot-223 3l tj3940s -1.2v -3l 1a reel contact us 1.2 v to-252 3l tj3940grs -1.2v -3l 1a reel contact us sot-223 3l tj3940s -1.5v -3l 1a reel contact us 1.5 v to-252 3l tj3940grs -1.5v -3l 1a reel contact us sot-223 3l tj3940s -1.8v -3l 1a reel contact us 1.8 v to-252 3l tj3940grs -1.8v -3l 1a reel contact us sot-223 3l tj3940s -2.5v -3l 1a reel contact us 2.5 v to-252 3l tj3940grs -2.5v -3l 1a reel contact us sot-223 3l tj3940s -3.3v -3l 1a reel contact us 3.3 v to-252 3l tj3940grs -3.3v -3l 1a reel contact us package type root name product code tj 3940 output voltage : 1.2v / 1.5v / 1.8v / 2.5v / 3.3v lead count : 3l s rs green mode g : halogen free blank : pb free : sot-223 : to-252 pin configuration sot-223 3l to-252 3l pin description sot-223 / to-252 3ld pin no. name function 1 gnd ground 2 vout output voltage 3 vin input voltage gnd vout vin gnd vout vin
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 3 - htc typical application - typical application circuit * tj3940 can deliver a continuous current of 1a over the full operating temperature. however, the output current is limited by the restriction of power dissipat ion which differs from packages. a heat sink may be required depending on the maximum power dissipation and maximum ambient temperature of application. with respect to the applied package, the maximum output current of 1a may be still undeliverable. * see application information.
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 4 - htc electrical characteristics (note 1) limits in standard typeface are for t j =25 , and limits in boldface type apply over the full operating temperature range . unless otherwise specified: v in (note 2) = v o(nom) + 1 v, i l = 10 ma, c in = 68 uf, c out = 33 uf parameter symbol test condit ion min. typ. max. unit output voltage tolerance v o 10 ma < i l < 1a v out +1 v < v in < 6 v -2 -3 0 2 3 % line regulation (note 3) v line v out +1 v < v in < 6 v - 0.10 0.22 0.25 %/v load regulation (note 3, 4) v load 10 ma < i l < 1a - 0.25 0.55 0.60 % dropout voltage (note 5) v drop i l = 1a - 450 550 600 mv i l = 100ma - 30 55 75 ground pin current (note 6) i gnd1 i l = 1a - 30 55 75 ua output peak current i peak 1.4 1.2 1.6 - a thermal shutdown temperature t sd - 165 - thermal shutdown hysteresis t sd - 10 - note 1. stresses listed as the absolute maximum ratings may c ause permanent damage to the device. these are for stress ratings. functional operating of the device at these or any other conditions beyond th ose indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rati ng conditions for extended periods may rema in possibly to affect device reliability. note 2. the minimum operating value for input voltage is equal to either (v out,nom + v drop ) or 2.5v, whichever is greater. note 3. output voltage line regulation is defined as the change in output voltage from the nominal value due to change in the i nput line voltage. output voltage load regulation is defined as the change in output voltage from the nominal value due to change in load current. note 4. regulation is measured at const ant junction temperature by using a 20ms curr ent pulse. devices are tested for load regu lation in the load range from 10ma to 1a. note 5. dropout voltage is defined as the minimum input to output differential voltage at which the output drops 2% below the n ominal value. dropout voltage specification applies only to output voltages of 2.5v and above. for output voltages below 2.5v, the dropout vo ltage is nothing but the input to output differential, since the minimum input voltage is 2.5v. note 6. ground current, or quiescent current, is the di fference between input and output currents. it's defined by i gnd1 = i in - i out under the given loading condition. the total current dr awn from the supply is the sum of the load current plus the ground pin current.
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 5 - htc typical operating characteristic ambient temperature vs. output voltage change output current vs. dropout voltage
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 6 - htc application information output capacitor the tj3940 requires a proper output capacitance to maintain stability and improve transient response over current. the esr of the output capacitor within the limits of 0.5 ? to 10 ? is required. a minimum capacitance value of 22 f of tantalum or aluminum electrolytic capacitor is recommended. in a case of ceramic capacitor, a minimum capacitance value of 10 f is required and additional resistance of minimum 1 ? should be added with the output capacitor in series to maintain its minimum esr. the resistance and capacitance have to be varied upon the load current. maximum output current capability the tj3940 can deliver a continuous current of 1a over the full operating ju nction temperature range. however, the output current is limited by the restriction of power dissipat ion which differs from packages. a heat sink may be required depending on the maximum power dissipation and maximum ambient temperature of application. with respect to the applied package, the maximum output current of 1a may be still undeliverable due to the rest riction of the power dissipation of tj3940. under all possible conditions, the junction temperature must be within the range specified under operating conditions. the temperatures over the device are given by: t c = t a + p d x ca / t j = t c + p d x jc / t j = t a + p d x ja where t j is the junction temperature, t c is the case temperature, t a is the ambient temperature, p d is the total power dissipation of the device, ca is the thermal resistan ce of case-to-ambient, jc is the thermal resistance of junction-to-case, and ja is the thermal resistance of junction to ambient. the total power dissipation of the device is given by: p d = p in ? p out = (v in x i in )?(v out x i out ) = (v in x (i out +i gnd )) ? (v out x i out ) = (v in - v out ) x i out + v in x i gnd where i gnd is the operating ground current of the device which is specified at the electrical characteristics. the maximum allowable temperature rise (t rmax ) depends on the maximum ambient temperature (t amax ) of the application, and the maximum allowable junction temperature (t jmax ): t rmax = t jmax ? t amax the maximum allowable value for junction-to-ambient thermal resistance, ja , can be calculated using the formula: ja = t rmax / p d = (t jmax ? t amax ) / p d tj3940 is available in sot-223, and to-252 pack ages. the thermal resistance depends on amount of copper area or heat sink, and on air flow. if the maximum allowable value of ja calculated above is as described in table 1, no heat sink is needed since the package can dissipate enough heat to satisfy these requirements. if the value for allowable ja falls near or below these limits, a heat sink or proper area of copper plane is required.
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 7 - htc table. 1. absolute maximum ratings of thermal resistance no heat sink / no air flow / no adjacent heat source / t a = 25c characteristic symbol rating unit thermal resistance junction-to-ambient / sot-223 ja-sot223 140 c/w thermal resistance junction-to-ambient / to-252 ja-to252 105 c/w in case that there is no cooling solution and no heat sink / minimum copper plane area for heat sink, the maximum allowable power dissipation of each package is as follow; characteristic symbol rating unit maximum allowable power dissipation at t a =25c / sot-223 p dmax-sot223 0.714 w maximum allowable power dissipation at t a =25c / to-252 p dmax-to252 0.952 w - please note that above maximum allowable power dissipation is based on the minimum copper plane area which does not exceed the proper foot print of the package. and the ambient temperature is 25c. if proper cooling solution such as heat sink, copper pl ane area, air flow is applied, the maximum allowable power dissipation could be increased. however, if the ambient temperature is increased, the allowable power dissipation would be decreased. for example, in case of sot-223 and to-252 package, ja-sot223 is 140 c/w and ja-to52 is 105 c/w, however, as shown in below graph, ja could be decreased with respect to the copper plane area. so, the specification of maximum power dissipation for an application is fixed, the proper copper plane area could be estimated by following graphs. as shown in graph, wider copper plane area leads lower ja . junction to ambient thermal resistance, ja vs. 1 ounce copper area [sot-223 package] junction to ambient thermal resistance, ja vs. 2 ounce copper area [to-252 package]
1a ultra low dropout linear regulator tj3940 jan. 2011 ? rev.1.0 - 8 - htc the maximum allowable power dissipation is also in fluenced by the ambient te mperature. with the above ja -copper plane area relationship, the maximum allowable power dissipation could be evaluated with respect to the ambient temperature. as s hown in graph, the higher copper plane area leads ja . and the higher ambient temperature leads lo wer maximum allowable power dissipation. all this relationship is based on the aforesaid equation ; ja = t rmax / p d = (t jmax ? t amax ) / p d . t. b . d
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