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www.fairchildsemi.com pentium is a registered trademark of intel corporation. powerpc is a trademark of ibm corporation. rev. 1.1.3 2/20/02 features ultra low dropout voltage, 0.4v typical at 5a remote sense operation fast transient response load regulation: 0.05% typical 0.5% initial accuracy on-chip thermal limiting 5-pin spak and to-263 packages applications pentium processors powerpc , amd k5 and k6 processors pentium support of gtl+ bus supply low voltage logic supply embedded processor supplies split plane regulator new 2.5v and 1.8v logic families description the fan1581, fan1581-1.5, and fan1581-2.5 are ultra-low dropout regulators with 5a output current capability. these devices have been optimized for low voltage applications including v tt bus termination, where transient response and minimum input voltage are critical. the fan1581 is ideal for low voltage microprocessor applications requiring a reg- ulated output from 1.3v to 5.7v with a power input supply of 1.75v to 6.5v. the fan1581-1.5 offers ?ed 1.5v with 5a current capabilities for gtl+ bus v tt termination. the fan1581-2.5 offers ?ed 2.5v with 5a current capability for logic ic operation and processors while minimizing the overall power dissipation. current limit ensures controlled short-circuit current. on-chip thermal limiting provides protection against any combination of overload and ambient temperature that would create exces- sive junction temperatures. the fan1581 series regulators are available in the 5-pin spak and to-263 power packages. typical applications 22 f v cntl = 5v 2.1v at 5a 10 f v in = 3.3v + + v in v sense v cntl adj v out fan1581 22 f v cntl = 5v 2.5v at 5a 10 f v in = 3.3v + 1 f + + v in v sense v cntl gnd v out fan1581?.5 86.6 ? 124 ? 22 f v cntl = 12v 5v at 5a 10 f v in = 5.75v + + v in v sense v cntl adj v out fan1581 374 ? 124 ? fan1581 5a adjustable/fixed ultra low dropout linear regulator
fan1581 product specification 2 rev. 1.1.3 2/20/02 pin assignments pin de?itions internal block diagram pin number pin name pin function descrition 1 vsense remote voltage sense . connect this pin to the load to permit true remote sensing and avoid trace drops. 2 adj/gnd adjust or ground. on the fan1581, this pin forms the feedback to determine the output voltage. on the fan1581-1.5 and -2.5, connect this pin to ground. 3 vout output voltage. this pin and the tab are output. 4 vcntl control voltage. this pin draws small-signal power to control the fan1581 circuitry. connect to a voltage higher than vin, as shown in the applications circuits. 5 vin input voltage. front view front view 123 4 5 front view 123 4 5 fan1581m-1.5, -2.5 fan1581m fan1581p front view fan1581p-1.5, -2.5 front view fan1581d front view fan1581d-1.5, -2.5 5-lead plastic to-263 jc =3 c/w* tab is out. 5-lead plastic spak jc =2 c/w* tab is out. 5-lead plastic to-252 dpak jc =3 c/w* tab is out. 12345 adj cntl out s in gnd cntl out s in adj cntl out s in gnd cntl out s in 12345 1 2 3 4 5 1 2 3 4 5 gnd cntl out s in adj cntl out s in *with package soldered to 0.5 square inch copper area over backside ground plane or internal power plane, ja can vary from 30 c/w to more than 40 c/w. other mounting techniques can provide a thermal resistance lower than 30 c/w. current limit thermal shutdown vref vin, power output sense adj v cntl , control 2 1 3 5 4 voltage loop amplifier
product specification fan1581 rev. 1.1.3 2/20/02 3 absolute maximum ratings electrical characteristics t j =25?, v out = v s , v adj = 0v unless otherwise speci?d. the ?denotes speci?ations which apply over the speci?d operating temperature range. notes: 1. see thermal regulation specifications for changes in output voltage due to heating effects. load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing. 2. line and load regulation are guaranteed up to the maximum power dissipation (18w). power dissipation is determined by input/output differential and the output current. guaranteed maximum output power will not be available over the full input/ output voltage range. 3. fan1581 only. 4. fan1581-1.5 only. 5. fan1581-2.5 only. parameter min. max. unit v in 7v v cntl 13.2 v operating junction temperature range 0 125 ? lead temperature (soldering, 10 sec.) 300 ? storage temperature range -65 150 ? parameter conditions min. typ. max. units reference voltage 3 v in = 2.0v, v cntl = 2.75v, i out = 10ma 1.243 1.250 1.257 v reference voltage 3 2.05v v in 5.5v, 2.7v v cntl 12v, 10ma i out 5a 1.237 1.250 1.263 v adjustable output voltage 3v v in 7v (function of vout), 10ma i out 5a vref 1.5 5.7 v output voltage 4 3v v in 7v, 10ma i out 5a 1.47 1.5 1.53 v output voltage 5 5.1v v in 7v, 10ma i out 5a 2.474 2.5 2.526 v line regulation 1,2 1.75v v in 5.5v, 2.5v v cntl 12v, i out = 10ma ?3mv load regulation 1,2 v in = 2.1v, v cntl = 2.75v, 10ma i out 5a ?5mv dropout voltage minimum (v cntl ? out ) v in = 2.05v, ? v ref = 1%, i out = 5a 1.05 1.18 v dropout voltage minimum (v in ? out ) v cntl = 2.75v, ? v ref = 1%, i out = 5a 0.4 0.5 v dropout voltage minimum v in v cntl = 2.75v, ? v ref = 1%, i out = 5a 0.5 0.6 v current limit v in = 2.05v, v cntl = 2.75v 5.2 a control pin current v in = 2.05v, v cntl = 2.75v, i out = 10ma ?6ma adjust pin current 3 v in = 2.05v, v cntl = 2.75v 50 120 ? minimum load current v in = 3.3v, v cntl = 5v 5.0 10 ma ripple rejection v in = 3.75v, v cntl = 3.75v, f = 120hz, c out = 22? tantalum, i out = 2.5a 60 80 db thermal resistance, junction to case to-263 spak 3 2 ?/w thermal regulation t a = 25?, 30ms pulse 0.002 0.02 %/w thermal shutdown 150 ?
fan1581 product specification 4 rev. 1.1.3 2/20/02 typical perfomance characteristics t=0 c t=125 c t=25 c 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 01 2 4 35 dropout voltage (v) reference voltage minimum load current (ma) output current (a) dropout voltage vs. output current load regulation vs. temperature reference voltage vs. temperature output voltage vs. temperature mimimum load current vs. temperature adjust pin current vs. temperature 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -75 -50 -25 25 50 75 100 125 150 175 0 output voltage deviation (%) junction temperature ( c) junction temperature ( c) ? =5a 1.275 1.270 1.265 1.260 1.255 1.250 1.245 1.240 1.235 1.230 1.225 output voltage (v) adjust pin current ( a) 3.70 3.65 3.60 3.55 3.50 3.45 3.40 3.35 3.30 3.25 3.20 100 90 80 70 60 50 40 30 20 10 0 -75 -50 -25 0 25 50 75 100 125 150 175 junction temperature ( c) -75 -50 -25 0 25 50 75 100 125 150 175 junction temperature ( c) -75 -50 -25 0 25 50 75 100 125 150 175 junction temperature ( c) -75 -50 -25 0 25 50 75 100 125 150 175 v out set with 1% resistors v out = 3.3v 1 note: 1. fan1581 only 10 8 6 4 2 0 note: 1. fan1581 only
product specification fan1581 rev. 1.1.3 2/20/02 5 typical perfomance characteristics (continued) 11 9 7 short-circuit current (a) power (w) ripple rejections (db) 5 3 -75 -50 -25 25 50 75 100 125 150 175 20 25 45 65 85 105 125 15 10 5 0 0 junction temperature ( c) case temperature frequency (hz) (v in v out ) 3v 0.5v v ripple 2v i out = 5a 90 90 70 60 50 40 30 20 10 0 10 100 1k 10k 100k short-circuit current vs.temeperature ripple rejection vs. frequency maximum power dissipation general the fan1581, fan1581-1.5, and fan1581-2.5 are three- terminal regulators optimized for gtl+ v tt termination and logic applications. these devices are short-circuit protected, and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150?. the fan1581 series provides low dropout voltage and fast transient response. frequency compensation uses capacitors with low esr while still maintaining stability. this is critical in addressing the needs of low voltage high speed microproces- sor buses like gtl+. v in and v cntl functions the fan1581 utilizes a dual supply approach to maximize ef?iency. the collector of the power device is brought out to the v in pin to minimize internal power dissipation under high current loads. v cntl provides power for the control circuitry and the drive for the output npn transistor. v cntl should be at least 1.2 v higher than the output volt- age. special care was taken to ensure there are no supply- sequencing problems. the output voltage will not turn on until both supplies are operating. if the control voltage comes up ?st, the output current will be typically limited to about 3.0 ma until the power input voltage comes up. if the power input voltage comes up ?st the output will not turn on at all until the control voltage comes up. the output can never come up unregulated. the fan1581 can also be used as a single supply device with the control and power inputs tied together. in this mode, the dropout is determined by the minimum control voltage. stability the fan1581 series requires an output capacitor as a part of the frequency compensation. it is recommended to use a 22? solid tantalum or a 100? aluminum electrolytic on the output to ensure stability. the frequency compensation of these
fan1581 product specification 6 rev. 1.1.3 2/20/02 devices optimizes the frequency response with low esr capaci- tors. in general, it is suggested to use capacitors with an esr of < 0.3 ? . it is also recommended to use bypass capacitors such as a 22? tantalum or a 100? aluminum on the adjust pin of the fan1581 for low ripple and fast transient response. when these bypassing capacitors are not used at the adjust pin, smaller values of output capacitors provide equally good results. protection diodes in normal operation, the fan1581 series does not require any protection diodes. for the fan1581, internal resistors limit internal current paths on the adjust pin. therefore, even with bypass capacitors on the adjust pin, no protection diode is needed to ensure device safety under short-circuit conditions. a protection diode between the input and output pins is usu- ally not needed. an internal diode between the input and the output pins on the fan1581 series can handle microsecond surge currents of 50a to 100a. even with large value output capacitors it is dif?ult to obtain those values of surge cur- rents in normal operation. only with large values of output capacitance, such as 1000? to 5000?, and with the input pin instantaneously shorted to ground can damage occur. a crowbar circuit at the input can generate those levels of current; a diode from output to input is then recommended, as shown in figure 1. usually, normal power supply cycling or system ?ot plugging and unplugging?will not generate current large enough to do any damage. the adjust pin can be driven on a transient basis ?v with respect to the output, without any device degradation. as with any ic regulator, exceeding the maximum input-to-output voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional. figure 1. optional protection diode ripple rejection in applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the fan1581 to ground reduces the output ripple by the ratio of v out /1.25v. the impedance of the adjust pin capacitor at the ripple frequency should be less than the value of r1 (typically in the range of 100 ? to 120 ? ) in the feedback divider network in figure 1. therefore, the value of the required adjust pin capacitor is a function of the input ripple frequency. for example, if r1 equals 100 ? and the ripple frequency equals 120hz, the adjust pin capacitor should be 22?. at 10khz, only 0.22? is needed. output voltage the fan1581 regulator develops a 1.25v reference voltage between the output pin and the adjust pin (see figure 2). placing a resistor r1 between these two terminals causes a constant current to ?w through r1 and down through r2 to set the overall output voltage. normally, this current is the speci?d minimum load current of 10ma. the current out of the adjust pin adds to the current from r1 and is typically 50?. its output voltage contribution is small and only needs consideration when a very precise output voltage setting is required. figure 2. basic regulator circuit load regulation the fan1581 family provides true remote sensing, eliminat- ing output voltage errors due to trace resistance. to utilize remote sensing, connect the vsense pin directly to the load, rather than at the vout pin. if the load is more than 1" away from the fan1581, it may be necessary to increase the load capacitance to ensure stability. thermal considerations the fan1581 series protect themselves under overload con- ditions with internal power and thermal limiting circuitry. however, for normal continuous load conditions, do not exceed maximum junction temperature ratings. it is important to consider all sources of thermal resistance from junction-to- ambient. these sources include the junction-to-case resistance, the case-to-heat sink interface resistance, and the heat sink resistance. thermal resistance speci?ations have been developed to more accurately re?ct device temperature and ensure safe operating temperatures. the electrical character- istics section provides a separate thermal resistance and fan1581 adj c2 22 f v out + c1 10 f + c adj + vcntl vsense vin vout r1 r2 d1 1n4002 (optional) v in v out fan1581 1.5, 2.5 gnd c2 22 f v out + c1 10 f + vcntl vsense vin vout d1 1n4002 (optional) v in v cntl c2 22 f v in v out v ref c1 10 f v cntl + + vcntl vsense vin adj vout fan1581 r1 r2 i adj 50 a v out = v ref (1+r2/r1) + i adj (r2)
product specification fan1581 rev. 1.1.3 2/20/02 7 maximum junction temperature for both the control circuitry and the power transistor. calculate the maximum junction temperature for both sections to ensure that both thermal limits are met. for example, look at using an fan1581m-1.5 to generate 5a @ 1.5v ?2% from a 3.3v source (3.2v to 3.6v). assumptions: ? in = 3.6v worst case ? out = 1.47v worst case ? out = 5a continuous ? a = 40? case-to-ambient = 5?/w (assuming both a heatsink and a thermally conductive material) the power dissipation in this application is: p d = (v in - v out ) * (i out ) = (3.6-1.47) * (5) = 10.65w from the speci?ation table, t j = t a + (p d ) * ( case-to-ambient + jc ) = 40 + (10.65) * (5 + 3) = 125? the junction temperature is within the maximum rating. junction-to-case thermal resistance is speci?d from the ic junction to the bottom of the case directly below the die. this is the lowest resistance path for heat ?w. proper mounting ensures the best thermal ?w from this area of the package to the heat sink. use of a thermally conductive material at the case-to-heat sink interface is recommended. use a thermally conductive spacer if the case of the device must be electri- cally isolated and include its contribution to the total thermal resistance. figure 3. application circuit (fan1581) table 1. bill of materials for application circuit for the fan1581 item quantity manufacturer part number description c1, c3 2 xicon l10v10 10f, 10v aluminum c2 1 xicon l10v100 100f, 10v aluminum c4 1 any 1f ceramic r1 1 generic 124 ? , 1% r2 1 generic 86.6 ? , 1% u1 1 fairchild fan1581p 5a regulator 100 f c2 10 f c3 v cntl = 5v 2.1v at 5a v in = 3.3v + 10 fc1 1 f c4 + v in v sense v cntl adj v out fan1581 124 ? 86.6 ? r2 r1 u1
fan1581 product specification 8 rev. 1.1.3 2/20/02 figure 4. application circuit (fan1581-1.5) table 2. bill of materials for application circuit for the fan1581-1.5 figure 5. application circuit (fan1581-2.5) table 3. bill of materials for application circuit for the fan1581-2.5 item quantity manufacturer part number description c1 1 xicon l10v10 10f, 10v aluminum c2 1 any 1f ceramic c3 1 xicon l10v100 100f, 10v aluminum u1 1 fairchild fan1581p-1.5 5a regulator item quantity manufacturer part number description c1 1 xicon l10v10 10f, 10v aluminum c2 1 any 1f ceramic c3 1 xicon l10v100 100f, 10v aluminum u1 1 fairchild fan1581p-2.5 5a regulator 100 f c3 v cntl = 3.3v 1.5v at 5a 10 f c1 v in = 2.5v + 1 f c2 + v in v sense v cntl gnd u1 v out fan1581 1.5 100 f c3 v cntl = 5v 2.5v at 5a 10 f c1 v in = 3.3v + 1 f c2 + + v in v sense v cntl gnd u1 v out fan1581 2.5
product specification fan1581 rev. 1.1.3 2/20/02 9 mechanical dimensions 5-lead to-263 package g d e-pin a c b f -c- h e j r (2plcs) -a- -b- symbol inches millimeters min. max. min. max. a .380 .405 9.65 10.29 b .575 .625 14.60 15.88 c .325 .380 8.25 9.66 d .055 1.40 e .020 .039 .50 .99 f .060 .072 1.52 1.83 g 0.45 .055 1.14 1.40 h .160 .190 4.06 4.83 j .090 0.110 2.28 2.80 k .018 .029 .457 .736 r .017 .019 0.43 0.48 notes: 1. dimensions are exclusive of mold flash and metal burrs. 2. standoff-height is measured from lead tip with ref. to datum b- . 3. foot length is measured with ref. to datum a- with lead surfac e (at inner r). 4. dimension exclusive of dambar protrusion or intrusion. 5. formed leads to be planar with respect to one another at seatin g place c-.
fan1581 product specification 10 rev. 1.1.3 2/20/02 mechanical dimensions (continued) 5-lead to-252 package (2.90) 10 0 1.78 1.40 gage plane 0.60 0.40 3 seating plane 0.13 max (1.54) 1 2 0.51 (5.09) (4.05) see detail a 0.25 m c 1 mc a 1.27 0.50 1.02 0.60 4 2 5.64 5.04 1 6.25 a 2.40 2.18 b 0.10 10.42 9.20 0.60 0.40 3.00 min b 6.56 min 6.00 min 3 5 0.57 0.07 0.69 0.15 1.27 5.08 5 4 6.80 6.35 6.30 5.90 3.81 1.00 (0.44) 1.27 1.27 land pattern recommendation notes: unless otherwise specified a) all dimensions are in millimeters. b) this package conforms to jedec, to-252, issue c, variation aa, dated nov. 1999. (rotated 90 ) scale: 2x detail a
fan1581 product specification 11 rev. 1.1.3 2/20/02 mechanical dimensions (continued) spak package l2 c c1 c2 seating plane 0.005 (0.13) 0.001 (0.03) r gage plane l1 5 1 b a l d b2 l3 m 0.010 (0,25) 0.004 (0,10) 3 6 thermal ta b (see note 3) e notes: 1. all linear dimensions are in inches (millimeters). 2. this drawing is subject to change without notice. 3. the center lead is in electrical contact with the thermal tab. 4. dimensions do not include mold protrusions, not to exceed 0.006 (0,15). a 0.360 0.350 symbol inches min. max. min. max. millimeters notes b 0.220 nom 0.268 0.070 c 0.080 c1 0.050 0.040 d e l 0.420 0.410 0.067 0.295 nom 0 8 e l1 c2 0.010 nom 9.14 8.89 0.375 0.365 9.52 9.27 5.59 nom 6.81 b1 b2 0.031 0.025 0.79 0.63 1.78 2.03 1.27 1.02 10.67 10.41 0.041 0.031 1.04 0.79 1.72 7.49 nom 0.25 nom 0 8 l2 0.360 0.350 9.14 8.89 l3 0.320 0.310 8.13 7.87 r 0.010 nom 0.25 nom b1 e
fan1581 product specification 2/20/02 0.0m 002 stock#ds30001581 ? 2001 fairchild semiconductor corporation life support policy fairchild s products are not authorized for use as critical components in life support devices or systems without the express written approval of the president of fairchild semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. a critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com disclaimer fairchild semiconductor reserves the right to make changes without further notice to any products herein to improve reliability, function or design. fairchild does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. ordering information product number package fan1581mx to-263 in tape and reel FAN1581PX spak in tape and reel fan1581dx to-252 dpak in tape and reel fan1581m15x to-263 in tape and reel fan1581p15x spak in tape and reel fan1581d15x to-252 dpak in tape and reel fan1581m25x to-263 in tape and reel fan1581p25x spak in tape and reel fan1581d25x to-252 dpak in tape and reel

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