View LM37101_7312053.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 1 - htc features ? fixed and adjustable output voltages to 1.24v ? 470mv typical dropout at 1a ideal for 3.0v to 2.5v conversion ideal for 2.5v to 1.8v or 1.5v conversion ? 1a minimum guaranteed output current ? 1% initial accuracy ? low ground current ? current limiting and thermal shutdown ? reversed-battery protection ? reversed-leakage protection ? fast transient response ? moisture sensitivity level 3 application ? battery powered equipments ? motherboards and graphic cards ? microprocessor power supplies ? peripheral cards ? high efficiency linear regulators ? battery chargers description sop-8 pkg to-252 pkg ordering information device package LM37101d-x.x sop-8 lm37102d LM37101rs-x.x to-252 lm37102rs x.x = output voltage = 1.5, 1.8, 2.5, 3.3, 5.0 the LM37101/2 is 1a low-dropout linear voltage regulat ors that provide low-volt age, high-current output. the LM37101/2 offers extremely low dropout (typically 470mv at 1a) and low ground current (typically 12ma at 1a). the LM37101 and lm37102 are fixed and adjustable regul ators, respectively, in sop-8 and to-252 package. the LM37101/2 is ideal for pc add-in cards that need to c onvert from standard 5v to 3. 3v, 3.3v to 2.5v or 2.5v to1.8v. a guaranteed maximum dropout voltage of 630mv overall operating conditions allows the LM37101/2 to provide2.5v from a supply as low as 3.13v and 1.8v fr om a supply as low as 2.43v. the LM37101/2 is fully protected with over current limiting, thermal shutdown , and reversed-battery protecti on. fixed voltages of 5.0v, 3.3v, 2.5v, 1.8v and 1.5v are available on LM37101 wi th adjustable output voltages to 1.24v on lm37102. absolute maximum ratings (note 1) characteristic symbol min. max. unit supply voltage v in - 0.3 + 20 v enable voltage v en - + 20 v output voltage v out -0.3 v in +0.3 v lead temperature (soldering, 5 sec) t sol - 260 storage temperature range t stg -65 + 150 free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 2 - htc operating ratings (note 2) characteristic symbol min. max. unit supply voltage v in + 2.25 + 16 v enable voltage v en + 2.25 + 16 v maximum power dissipation pd (max-sop8) (note 3) 0.77 w pd (max-to-252) (note 3) 0.952 junction temperature t j -40 + 125 package thermal resistance ja-sop-8 130 /w jc-sop-8 30 /w ordering information v out package order no. description supplied as status 1.5v sop-8 LM37101d-1.5 1a, fixed, enable reel contact us. to-252 LM37101rs-1.5 1a, fixed, enable reel contact us. 1.8v sop-8 LM37101d-1.8 1a, fixed, enable reel contact us. to-252 LM37101rs-1.8 1a, fixed, enable reel contact us. 2.5v sop-8 LM37101d-2.5 1a, fixed, enable reel contact us. to-252 LM37101rs-2.5 1a, fixed, enable reel contact us. 3.3v sop-8 LM37101d-3.3 1a, fixed, enable reel contact us. to-252 LM37101rs-3.3 1a, fixed, enable reel contact us. 5.0v sop-8 LM37101d-5.0 1a, fixed, enable reel contact us. to-252 LM37101rs-5.0 1a, fixed, enable reel contact us. adj sop-8 lm37102d 1a, adjustable, enable reel active to-252 lm37102rs 1a, adjustable, enable reel contact us. package type root name product code 3710x output voltage : 1.5v / 1.8v / 2.5v / 3.3v / 5.0v / blank(adj only) 37101 : fixed output 37102 : adjustable output tj d rs : sop-8 : to-252 free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 3 - htc pin configuration sop-8 to-252 5l pin description pin no. to-252 5l pkg sop-8 pkg name function name function 1 en chip enable en chip enable 2 vin input supply vin input supply 3 gnd ground vout output voltage 4 vout output voltage flg / adj error flag output or output adjust 5 flg / adj error flag output or output adjust gnd ground 6 / 7 / 8 - - gnd ground typical application in out en flg gnd 100k LM37101 2.5v error flag output 3.3v enable shutdown 2.5v / 1a regulator with error flag in out en adj gnd lm37102 1.5v 2.5v enable shutdown r1 r2 1.5v / 1a adjustable regulator en 1 vin 2 vout 3 flg/adj 4 8 gnd 7 gnd 6 gnd 5 gnd flg/adj vout gnd (tab) vin en 5 4 3 2 1 free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 4 - htc electrical characteristics v in = v out +1v; v en = 2.25v; t j = 25 c, bold values indicate -40 c t j +125 c; unless noted symbol parameters condition min. typ. max. unit v out output voltage 10ma 10ma i out 1a, v out +1v v in 8v -1 -2 1 2 % % line regulation i out =10ma, v out +1v v in 16v 0.06 0.5 % load regulation v in = v out +1v, 10ma i out 1a 0.2 1 % v out / t output voltage temp. coefficient (note 4) 40 100 ppm/ c v do dropout voltage (note 5) i out =100ma, v out = -1% 170 210 250 mv mv i out =500ma, v out = -1% 315 mv i out =750ma, v out = -1% 390 500 mv i out =1a, v out = -1% 470 570 630 mv mv i gnd ground current (note 6) i out =100ma, v in = v out +1v 700 a i out =500ma, v in = v out +1v 4 ma i out =750ma, v in = v out +1v 7 ma i out(lim) current limit v out =0v, v in =v out +1v 1.8 2.5 a enable input v en enable input voltage logic low (off) 0.8 v logic high (on) 2.25 v i en enable input current v en =2.25v 1 15 30 75 a a v en =0.8v 2 4 a a t en delay time to nominal output voltage (note 7) i out =10ma, v in =v out +1v, v en =0v to v in 50 500 s i out =500ma, v in =v out +1v, v en =0v to v in 250 2000 i out =1.0a, v in =v out +1v, v en =0v to v in 350 3000 flag output i flg (leak) output leakage current v oh =16v 0.01 1 2 a a v flg (do) output low voltage (note 8) v in =0.9.v out nominal, i ol =250 a 240 300 400 mv mv v flg low threshold % of v out 93 % high threshold % of v out 99.2 % hysteresis 1 % free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 5 - htc lm37102 only v ref reference voltage 1.228 1.215 1.24 1.252 1.265 v v (note 9) 1.203 1.277 v i ref adjust pin bias current 40 80 120 na na v ref / t reference voltage temp. coefficient (note 4) 20 ppm/ c i adj / t adjust pin bias current temp. coefficient 0.1 99.2 na/ c note 1. exceeding the absolute maxi mum ratings may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. pd (max)= (t j (max) - t a ) ja , where ja -junction-to-ambient thermal resistance. note 4. output voltage temperature coefficient is v out (worst case) (t j(max) - t j(min) ) where t j(max) is +125c and t j(min) is 0c. note 5. v do = v in - v out when v out decreases to 99% of its nominal output voltage with v in = v out + 1v. for output voltages below 2.25v, dropout voltage is the input-to-output voltage differential with the minimum input voltage being 2.25v. minimum input operating voltage is 2.25v. note 6. i gnd is the quiescent current. i in = i gnd + i out. note 7. delay time is measured after v en =v in . c in =c out =10 f. note 8. for adjustable device and fixed device with v out 2.5v note 9. v ref v out (v in - 1v), 2.25v v in 16v, 10ma i l 1 a. free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 6 - htc typical operating characteristics free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 7 - htc typical operating characteristics free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 8 - htc application information the LM37101/2 is a high-performance low-dropout voltage regulator suitable for moderate to high-current voltage regulator applications. its 630mv dropout vo ltage at full load and over temperature makes it especially valuable in battery-powered systems and as high-efficiency noise filters in post-regulator applications. unlike older npn-pass transistor de-sig ns, where the minimum dropout voltage is limited by the base-to-emitter voltage drop and collect or-to-emitter saturation voltage, dropout performance of the pnp output of these devices is limited only by the low vce saturation voltage. a trade-off for the low dropout voltage is a varying base drive requirement. the LM37101/2 regulator is fully protected from dam age due to fault conditions. linear current limiting is provided. output current during overl oad conditions is constant. thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. transient protection allows device (and load) survival even when the input voltage spikes above and below nominal. the output structure of these regulators allows voltages in excess of the des ired output voltage to be applied without reverse current flow. output capacitor the LM37101/2 requires an output capacitor to maintain stability and improve transient response. proper capacitor selection is important to ensure proper oper ation. the LM37101/2 output capacitor selection is dependent upon the esr (equivalent series resistance) of the output capacitor to maintain stability. when the output capacitor is 10 f or greater, the output capacitor should have an esr less than 2 ? . this will improve transient response as well as promote stability. ultra-low esr capacitors (<100m ? ), such as ceramic chip capacitors, may promote the instability. these very low esr levels may cause an oscillation and/or underdamped transient response. a low esr so lid tantalum capacitor works extremely well and provides a good transient response and the stability ov er the temperature range. aluminum electrolytes can also be used, as long as the capacitor esr is <2 ? . the value of the output capacitor can be increased without limit. higher capacitance values help one to improve transient response and ripple rejection and reduce an output noise. input capacitor an input capacitor of 1 f or greater is recommended when the device is more than 4 inches away from the bulk ac supply capacitance or when the supply is a battery. in the case of ceramic chip capacitor, 10uf capacitance is recommended. larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage. error flag the LM37101 features an error flag (flg), which moni tors the output voltage and signals an error condition when this voltage drops 5% below its expected value. the error flag is an open-collector output that pulls low under fault conditions and may sink up to 10ma. low output voltage signifies a number of possible problems, including an over current fault (the device is in current limit) or low input voltage. the flag output is inoperative during over temperature conditions. a pu ll-up resistor from flg to either v in or v out is required for proper operation. for information regarding the minimum and maximum values of pull-up resistance, refer to the graph in the typical characteri stics section of the data sheet. free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 9 - htc enable input the LM37101 and lm37102 versions feature an active-high enable input (en) that allows on-off control of the regulator. current drain reduces to ?zero? when the devi ce is shutdown, with only micro amperes of leakage current. the en input has ttl/cmos compatible thresholds for simple logic interfacing. en may be directly tied to v in and pulled up to the maximum supply voltage transient response and 3.3v to 2.5v or 2.5v to 1.8v conversion the LM37101/2 has excellent transient response to variations in input voltage and load current. the device has been designed to respond quickly to load current variations and input voltage variations. large output capacitors are not required to obtain this performance. a standard 10f output capacitor, preferably tantalum, is all that is required. larger values he lp to improve performance even further. by virtue of its low-dropout voltage, this device does no t saturate into dropout as readily as similar npn- based de-signs. when converting from 3. 3v to 2.5v or 2.5v to 1.8v, the npn based regulators are already operating in dropout, with typical drop out requirements of 1.2v or greater. to convert down to 2.5v or 1.8v without operating in dropout, npn-based regulators requi re an input voltage of 3.7v at the very least. the lm37100 regulator will provide excellent performance with an input as low as 3.0v or 2.5v respectively. this gives the pnp based regulators a distinct advant age over older, npn based linear regulators. minimum load current the LM37101/2 regulator is specified between finite load s. if the output current is too small, leakage currents dominate and the output voltage rises. a 10ma minimum load current is necessary for proper regulation. adjustable regulator design the lm37102 allows programming the output vo ltage any-where between 1.24v and the 16v maximum operating rating of the family. two resistors ar e used. resistors can be quite large, up to 1m ? , because of the very high input impedance and low bias current of the se nse comparator: the resistor values are calculated by : r1=r2(vout/1.240-1) where vout is the desired output voltage. figu re 1 shows component definition. applications with widely varying load currents may scal e the resistors to draw the minimum load current required for proper operation (see below). the cu rrent consumed by feedback resisters r1 and r2 is calculated by: i res = vout / (r1+ r2). figure 1. adjustable regulator with resistors maximum output current capability the LM37101/2 can deliver a continuous current of 1a over the full operating junction temperature range. however, the output current is limited by the restriction of pow er dissipation which differs from packages. a heat sink may be required depending on the maximum power dissipation and maximum ambient temperature of free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 10 - htc application. with respect to the applied package, the maximum output current of 1a may be still undeliverable due to the restriction of the power dissipation of LM37101/2. under a ll possible conditions, the junction temperature must be within the range specified under operating conditions. th e 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 resistance 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 t he 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 LM37101/2 is available in sop-8 pack age. 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 over 130c/w for sop-8 package, 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. in summary, the absolute maximum ratings of thermal resistances are as follow: absolute maximum ratings of thermal resistance characteristic symbol rating unit thermal resistance junction-to-ambient / sop-8 ja-sop-8 130 c/w thermal resistance junction-to-ambient / to-252 ja-to-252 95 c/w no heat sink / no air flow / no adjacent heat source / 20 mm 2 copper area. (t a =25c) free datasheet http:///
1a low-voltage low-dropout regulator LM37101/37102 nov. 2011 ? r1.1 - 11 - htc power disspation(pd) vs. copper area 0.4 0.6 0.8 1 1.2 1.4 1.6 10 100 1000 copper area (mm 2 ) power disspation, pd (w) @ t j =125 thermal resistance( ja) vs. copper area 40 60 80 100 120 140 10 100 1000 copper area (mm 2 ) thermal resistance, ja ( /w) free datasheet http:///

▲Up To Search▲

Price & Availability of LM37101

	To Download LM37101 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .