iru1150(pbf) 1 rev. 1.8 www.irf.com 4a ultra low dropout positive adjustable regulator the iru1150 is a 4a regulator with extremely low drop- out voltage using a proprietary bipolar process that achieves comparable equivalent on-resistance to that of discrete mosfets. this product is specifically designed to provide well regulated supply for applications requir- ing 2.8v or lower voltages from 3.3v atx power supplies where high efficiency of a switcher can be achieved with- out the cost and complexity associated with switching regulators. one such application is the new graphic chip sets that require anywhere from 2.4v to 2.7v supply such as the intel i 740 chip set. description 0.7v dropout at 4a fast transient response 1% voltage reference initial accuracy built-in thermal shutdown applications features 3.3v to 2.7v intel i 740 chip set typical application data sheet no. pd94129reva figure 1 - typical application of iru1150 in a 3.3v to 2.7v for i 740 chip. 3.3v iru1150 2.7v c1 100uf c3 100uf 5v c2 100uf r1 102 r2 118 1 2 3 4 5 v sense adj v out v ctrl v in package order information t j ( c) 5-pin plastic 5-pin plastic 8-pin plastic to-263 (m) ultra thin-pak tm (p) soic (s) 0 to 125 iru1150cm iru1150cp iru1150cs leadfree part basic part (non-lead free) t j ( c) 5-pin plastic 5-pin plastic 8-pin plastic to-263 (m) ultra thin-pak tm (p) soic (s) 0 to 125 not available not available IRU1150CSPBF
2 rev. 1.8 iru1150(pbf) www.irf.com absolute maximum ratings input voltage (v in ) .................................................... 7v control input voltage (v ctrl ) ..................................... 14v power dissipation ..................................................... internally limited storage temperature range ...................................... -65c to 150c operating junction temperature range ..................... 0c to 150c package information 5-pin plastic to-263 (m) 5-pin plastic ultra thin-pak tm (p) 8-pin plastic soic (s) ja =35 c/w for 0.5" square pad ja =35 c/w for 0.5" square pad ja =55 c/w for 1" sq pad area electrical specifications unless otherwise specified, these specifications apply over c in =1 f, c out =10 f, and t j =0 to 125 8 c. typical values refer to t j =25 8 c. v out =v sense . parameter sym test condition min typ max units v sense adj v in v ctrl v out 4 3 2 1 5 6 7 8 top view v out v out v out v sense adj v out v ctrl v in front view 1 2 3 4 5 tab is v out v sense adj v out v ctrl v in front view 1 2 3 4 5 tab is v out reference voltage line regulation load regulation (note 1) dropout voltage (note 2) (v ctrl - v out ) dropout voltage (note 2) (v in - v out ) current limit minimum load current (note 3) thermal regulation ripple rejection control pin current adjust pin current v ctrl =2.7 to 12v, v in =2.05v to 5.5v, io=10ma to 4a, v adj =0v v ctrl =2.5v to 7v, v in =1.75v to 5.5v, io=10ma, v adj =0v v ctrl =2.75v, v in =2.1v, io=10ma to 4a, v adj =0v v adj =0v for all conditions below: v in =2.05v, io=1.5a v in =2.05v, io=3a v in =2.05v, io=4a v adj =0v for all conditions below: v ctrl =2.75v, io=1.5a v ctrl =2.75v, io=3a v ctrl =2.75v, io=4a v ctrl =2.75v, v in =2.05v, ? vo=100mv, v adj =0v v ctrl =5v, v in =3.3v, v adj =0v 30ms pulse v ctrl =5v, v in =5v, io=4a, v adj =0v, t j =25 8 c, v ripple =1v pp at 120hz v adj =0v for all below conditions: v ctrl =2.75v, v in =2.05v, io=1.5a v ctrl =2.75v, v in =2.05v, io=3a v ctrl =2.75v, v in =2.05v, io=4a v ctrl =2.75v, v in =2.05v, v adj =0v 1.225 -5 -5 4.2 1.250 -0.2 3 1.00 1.05 1.13 0.26 0.50 0.70 4.65 1 0.01 70 16 36 67 50 1.275 +5 +5 1.15 1.15 1.20 0.38 0.60 1.15 6 10 25 50 85 v mv mv v v a ma %/w db ma a v ref i adj
iru1150(pbf) 3 rev. 1.8 www.irf.com this pin is the positive side of the reference which allows remote load sensing to achieve excellent load regulation. a resistor divider from this pin to the v out pin and ground sets the output voltage. the output of the regulator. a minimum of 10 f capacitor must be connected from this pin to ground to insure stability. this pin is the supply pin for the internal control circuitry as well as the base drive for the pass transistor. this pin must always be higher than the v out pin in order for the device to regulate. (see specifications) the input pin of the regulator. typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum drop out voltage during the load transient response. this pin must always be higher than v out in order for the device to regulate. (see specifications) note 1: low duty cycle pulse testing with kelvin con- nections is required in order to maintain accurate data. note 2: dropout voltage is defined as the minimum dif- ferential between v in and v out required to maintain regu- lation at v out . it is measured when the output voltage drops 1% below its nominal value. note 3: minimum load current is defined as the mini- mum current required at the output in order for the out- put voltage to maintain regulation. typically the resistor dividers are selected such that it automatically main- tains this current. pin # pin symbol pin description pin descriptions 1 2 3 4 5 v sense adj v out v ctrl v in block diagram figure 2 - simplified block diagram of the iru1150. v ctrl v in v sense adj v out thermal shutdown current limit 1.25v + + 5 4 3 1 2
4 rev. 1.8 iru1150(pbf) www.irf.com application information introduction the iru1150 adjustable regulator is a five-terminal de- vice designed specifically to provide extremely low drop- out voltages comparable to the pnp type without the disadvantage of the extra power dissipation due to the base current associated with pnp regulators. this is done by bringing out the control pin of the regulator that provides the base current to the power npn and con- necting it to a voltage that is grater than the voltage present at the v in pin. this flexibility makes the iru1150 ideal for applications where dual inputs are available such as a computer mother board with an atx style power sup- ply that provides 5v and 3.3v to the board. one such application is the new graphic chip sets that require any- where from 2.4v to 2.7v supply such as the intel i 740 chip set. the iru1150 can easily be programmed with the addition of two external resistors to any voltages within the range of 1.25 to 5.5 v. another major require- ment of these graphic chips such as the intel i 740 is the need to switch the load current from zero to several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300 to 500ns of current step at the regulator. in addition, the output voltage tol- erances are also extremely tight and they include the transient response as part of the specification. the iru1150 is specifically designed to meet the fast current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with the need for fewer number of output capacitors. another fea- ture of the device is its true remote sensing capability which allows accurate voltage setting at the load rather than at the device. output voltage setting the iru1150 can be programmed to any voltages in the range of 1.25v to 5.5v with the addition of r1 and r2 external resistors according to the following formula: v out r1 r2 v in v ctrl v ref i adj = 50ua iru1150 v sense adj v out v ctrl v in r1 r2 v in v ctrl r l iru1150 v sense adj v out v ctrl vin figure 3 - typical application of the iru1150 for programming the output voltage. the iru1150 keeps a constant 1.25v between the v sense pin and the v adj pin. by placing a resistor r1 across these two pins and connecting the v sense and v out pin together, a constant current flows through r1, adding to the iadj current and into the r2 resistor producing a volt- age equal to the (1.25/r1) 3 r2 + i adj 3 r2. this voltage is then added to the 1.25v to set the output voltage. this is summarized in the above equation. since the minimum load current requirement of the iru1150 is 10ma, r1 is typically selected to be a 121 ? resistor so that it automatically satisfies this condition. notice that since the i adj is typically in the range of 50 a it only adds a small error to the output voltage and should be considered when very precise output voltage setting is required. load regulation since the iru1150 has separate pins for the output (v out ) and the sense (v sense ), it is ideal for providing true re- mote sensing of the output voltage at the load. this means that the voltage drops due to parasitic resistance such as pcb traces between the regulator and the load are compensated for using remote sensing. figure 4 shows a typical application of the iru1150 with remote sensing. figure 4 - schematic showing connection for best load regulation. v out = v ref 3 1+ +i adj 3 r2 r2 r1 ( ) where: v ref = 1.25v typically i adj = 50 a typically r 1 and r 2 as shown in figure 3:
iru1150(pbf) 5 rev. 1.8 www.irf.com v out = 2.7v v in = 3.3v v ctrl = 5v i out = 2a (dc avg) assuming, the following conditions: calculate the maximum power dissipation using the fol- lowing equation: using table below select the proper package and the amount of copper board needed. pkg copper ja ( c/w) max pd max pd area ( t a =25 c ) ( t a =45 c ) to-263 1.4"x1.4" 25 4.4w 3.6w to-263 1.0"x1.0" 30 3.7w 3.0w to-263 0.7"x0.7" 35 3.1w 2.6w to-263 pad size 45 2.4w 2.0w so-8 1.0"x1.0" 55 2.0w 1.63w note: above table is based on the maximum junction temperature of 135 8 c. as shown in the above table, any of the two packages will do the job. for low cost applications the soic 8-pin package is recommended. p d = 2 3 (3.3 - 2.7)+ 3 (5 - 2.7) = 1.28w p d = i out 3 (v in - v out )+ 3 (v ctrl - v out ) 2 60 ( ) i out 60 ( ) stability the iru1150 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. typical designs for the microprocessor applications use standard electrolytic capacitors with typical esr in the range of 50 to 100m ? and an output capacitance of 500 to 1000 f. fortunately as the ca- pacitance increases, the esr decreases resulting in a fixed rc time constant. the iru1150 takes advantage of this phenomena in making the overall regulator loop stable. for most applications a minimum of 100 f aluminum electrolytic capacitor such as sanyo, mvgx series, panasonic fa series as well as the nichicon pl series insures both stability and good transient response. thermal design the iru1150 incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable maximum junction temperature. although this device can operate with junction tempera- tures in the range of 150 8 c, it is recommended that the selected heat sink be chosen such that during maxi- mum continuous load operation the junction tempera- ture is kept below this number. the example below shows the steps in selecting the proper surface mount package.
6 rev. 1.8 iru1150(pbf) www.irf.com (m) to-263 package 5-pin symbol a b c d e g h k l m n p r s u v min 10.05 8.28 4.31 0.66 1.14 1.575 14.605 1.143 0.00 2.49 0.33 2.286 0 8 1.143 max 10.668 9.169 4.597 0.91 1.40 1.829 15.875 1.68 0.305 2.74 0.58 2.794 8 8 2.67 6.50 ref 7.75 ref note: all measurements are in millimeters. g d a e m l n u c b k p v r s h c l
iru1150(pbf) 7 rev. 1.8 www.irf.com (p) ultra thin-pak tm 5-pin note: all measurements are in millimeters. symbol a a1 b c d e g h k l m n p r u v min 9.27 8.89 7.87 1.78 0.63 10.41 0.76 0.03 0.89 0.79 3 8 max 9.52 9.14 8.13 2.03 0.79 10.67 1.27 0.13 1.14 1.04 6 8 0.25 nom 1.72 0.25 5.59 nom 7.49 nom a e m l n u c b k p v h g d r l c a1
8 rev. 1.8 iru1150(pbf) www.irf.com (s) soic package 8-pin surface mount, narrow body symbol a b c d e f g h i j k l t min 4.80 0.36 3.81 1.52 0.10 0.19 5.80 0 8 0.41 1.37 max 4.98 0.46 3.99 1.72 0.25 0.25 6.20 8 8 1.27 1.57 1.27 bsc 0.53 ref 7 8 bsc 8-pin note: all measurements are in millimeters. pin no. 1 i k h detail-a detail-a 0.38 6 0.015 x 45 8 t g f d a b c e l j
iru1150(pbf) 9 rev. 1.8 www.irf.com pkg desig m p s package description to-263 ultra thin-pak tm soic, narrow body parts per tube 50 75 95 parts per reel 750 2500 2500 package shipment method pin count 5 5 8 t & r orientation fig a fig b fig c feed direction figure a feed direction figure b feed direction figure c 1 1 1 1 1 1 1 1 1 ir world headquarters: 233 kansas st., el segundo, california 90245, usa tel: (310) 252-7105 tac fax: (310) 252-7903 visit us at www.irf.com for sales contact information data and specifications subject to change without notice. 5/2/2005
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