www.fairchildsemi.com rev. 1.0.3 9/24/01 features ? fast transient response ? low dropout voltage at up to 4.5a ? load regulation: 0.5% typical ? on-chip thermal limiting ? standard to-220, to-263 center cut, and to-252 packages applications ? desktop pcs, risc and embedded processors supply ? gtl, sstl logic reference bus supply ? low voltage v cc logic supply ? battery-powered circuitry ? post regulator for switching supply ? cable and adsl modems dsp core supply ? set top boxes and web boxes modules supply description the fan1084, fan1084-1.5, and fan1084-3.3 are low dropout three-terminal regulators with 4.5a 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 fan1084 is ideal for low voltage microprocessor applica- tions requiring a regulated output from 1.5v to 3.6a with an input supply of 5v or less. the fan1084-1.5 offers ?xed 1.5v with 4.5a current capabilities for gtl+ bus v tt termination. the fan1084-3.3 offers a ?xed 3.3v output at 4.5a. on-chip thermal limiting provides protection against any combination of overload and ambient temperature that would create excessive junction temperatures. the fan1084 series regulators are available in the industry- standard to-220, to-263 center cut, and to-252 (dpak) power packages. block diagram 10 f 22 f 124 ? 124 ? v in = 5v 2.5v at 4.5a + + v in adj v out fan1084 10 f 22 f v in = 3.3v 1.5v at 4.5a + + v in gnd v out fan1084-1.5 fan1084 4.5a adjustable/fixed low dropout linear regulator
fan1084 product specification 2 rev. 1.0.3 9/24/01 pin assignments absolute maximum ratings parameter min. max. unit v in 7v operating junction temperature range 0 125 c storage temperature range ?5 150 c lead temperature (soldering, 10 seconds) 300 c gnd out front view 3-lead plastic to-220 jc =3 c/w* 3-lead plastic to-263 jc =3 c/w* *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 may provide better power dissipation than 30 c/w. fan1084m-3.3 fan1084m-1.5 in 12 3 adj out front view in 12 3 gnd front view in 12 3 fan1084m fan1084t fan1084t-3.3 fan1084t-1.5 adj front view in 12 3 3-lead plastic to-252 jc =3 c/w* fan1084d-3.3 fan1084d-1.5 gnd front view in 123 fan1084d adj front view in 123 tab is out. tab is out.
product specification fan1084 rev. 1.0.3 9/24/01 3 electrical characteristics operating conditions: 4.75 v in < 5.25v, t j = 25 c unless otherwise speci ed. 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. power dissipation is determined by input/ output differential and the output currrent. guaranteed maximum output power will not be available over the full input/output voltage range. 3. fan1084 only. 4. guaranteed by design. 5. fan1084-1.5 only. 6. fan1084-3.3 only. parameter conditions min. typ. max units reference voltage 3 adj connected to ground, i out = 10ma 1.23 1.250 1.27 v output voltage 5 i out = 10ma 1.475 1.5 1.525 v output voltage 6 i out = 10ma 3.234 3.3 3.366 v line regulation 1, 2 i out = 10ma 0.5 2 % load regulation 1, 2 10ma i out 4.5a 0.5 2.5 % dropout voltage ? v ref% = 2%, i out = 4.5a 1.5 v current limit (v in v out ) = 2v 5.5 a adjust pin current 3 35 100 mimimum load current 4 1.5v (v in v out ) 5.75v 10 ma quiescent current 4 v in = 5v 4 ma thermal resistance, junction to case to-220 3 c/w to-263 center cut, to-252 3 c/w thermal shutdown 4 150 c typical performance characteristics figure 1. maximum power dissipation 20 15 10 5 0 25 45 65 85 105 125 power (w) case temperature
fan1084 product specification 4 rev. 1.0.3 9/24/01 applications information general the fan1084, fan1084-1.5, and fan1084-3.3 are three- terminal regulators optimized for gtl+ v tt termination and logic applications. these devices are short-circuit pro- tected, and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150c. the fan1084 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 micro- processor buses like gtl+. stability the fan1084 series requires an output capacitor as a part of the frequency compensation. it is recommended to use a 22f solid tantalum or a 100f aluminum electrolytic on the output to ensure stability. the frequency compensation of these devices optimizes the frequency response with low esr capacitors. in general, it is suggested to use capacitors with an esr of <1 ? . it is also recommended to use bypass capacitors such as a 22f tantalum or a 100f aluminum on the adjust pin of the fan1084 for low ripple and fast transient response. when t hese bypassing capacitors are not used at the adjust pin, smaller values of output capacitors provide equally good results. protection diodes in normal operation, the fan1084 series does not require any protection diodes. for the fan1084, 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 condi- tions. a protection diode between the input and output pins is usually not needed. an internal diode between the input and the output pins on the fan1084 series can handle micro- second surge currents of 50a to 100a. even with large value output capacitors it is dif?cult to obtain those values of surge currents in normal operation. only with large values of output capacitance, such as 1000 f to 5000 f, 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 recom- mended, as shown in figure 2. usually, normal power supply cycling or system hot plugging and unplugging will not generate current large enough to do any damage. the adjust pin can be driven on a transient basis 7v with respect to the ouput, 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 2. optional protection ripple rejection in applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the fan1084 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 2. 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 22f. at 10khz, only 0.22f is needed. output voltage the fan1084 regulator develops a 1.25v reference voltage between the ouput pin and the adjust pin (see figure 3). placing a resistor r1 between these two terminals causes a constant current to ?ow through r1 and down through r2 to set the overall output voltage. normally, this current is the speci?ed minimum load current of 10ma. fan1084 adj c2 22 f v out + c1 10 f + + in out d1 1n4002 (optional) v in fan1084-1.5 gnd c2 22 f v out + c1 10 f + in out d1 1n4002 (optional) v in r1 r2 c adj
product specification fan1084 rev. 1.0.3 9/24/01 5 the current out of the adjust pin adds to the current from r1. its output voltage contribution is small and only needs consid- eration when a very precise output voltage setting is required. figure 3. connection for best load regulation load regulation it is not possible to provide true remote load sensing because the fan1084 series are three-terminal devices. load regula- tion is limited by the resistance of the wire connecting the reg- ulator to the load. load regulation per the data sheet speci?cation is measured a t the bottom of the package. for ?xed voltage devices, negative side sensing is a true kelvin connection with the ground pin of the device returned to the negative side of the load. this is illustrated in figure 4. figure 4. connection for best load regulation for adjustable voltage devices, negative side sensing is a true kelvin connection with the bottom of the output divider returned to the negative side of the load. the best load regula- tion is obtained when the top of the resistor divider r1 connects directly to the regulator output and not to the load. figure 5 illustrates this point. if r1 connects to the load, then the effective resistance between the regulator and the load would be: r p x (1 + r2/r1), r p = parasitic line resistance the connection shown in figure 5 does not multiply r p by the divider ration. as an example, r p is about four milliohms per foot with 16-gauge wire. this translates to 4mv per foot at 1a load current. at higher load currents, this drop represents a signi?cant percentage of the overall regulation. it is important to keep the positive lead between the regulator and the load as short as possible and to use large wire or pc board traces. figure 5. connection for best load regulation thermal conditions the fan1084 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 impor- tant to consider all sources of thermal resistance from junc- tion-to-ambient. these sources include the junction-to-case resistance, the case-to-heatsink interface resistance, and the heat sink resistance. thermal resistance speci?cations have been developed to more accurately re?ect device tempera- ture and ensure safe operating temperatures. the electrical characteristics section provides a separate thermal resistance and maximum junction temperature for both the control cir- cuitry and the power transistor. calculate the maximum junc- tion temperature for both sections to ensure that both thermal limits are met. for example, look at using a fan1084t to generate 4.5a @ 1.5v from a 3.3v source (3.2v to 3.6v). assumptions ?v in = 3.4v worst case ?v out = 1.475v worst case ?i out = 4.5a continuous ?t a = 60 c ? case-to-ambient = 5 c/w (assuming both a heatsink and a thermally conductive material) the power dissipation in this application is: p d = (v in C v out ) * (i out ) = (3.6 C 1.475) * (4.5) = 9.6w from the speci?cation table: t j = t a + (p d ) * ( case-to-ambient + jc ) = 60 + (9.6) * (5 + 3) = 137 c the junction temperature is below the maximum thermal limit. fan1084 adj c2 22 f v out + c1 10 f i adj 35 a + in out v in r1 r2 v ref fan1084-1.5 gnd r l r p parasitic line resistance in out v in fan1084 adj r l r1* r2* *connect r1 to case connect r2 to load r p parasitic line resistance in out v in
fan1084 product specification 6 rev. 1.0.3 9/24/01 junction-to-case thermal resistance is speci?ed from the ic junction to the bottom of the case directly below the die. this is the lowest resistance path for heat ?ow. proper mounting ensures the best thermal ?ow 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. the cases of the fan1084 series are directly con- nected to the output of the device. figure 6. application circuit table 1. bill of materials for application circuit for the fan1084 figure 7. application circuit (fan1084-1.5) table 2. bill of materials for application circuit for the fan1084-1.5 item quantity manufacturer part number description c1 1 xicon l10v10 10f, 10v aluminum c2, c3 2 xicon l10v100 100f, 10v aluminum r1, r2 2 generic 124 ? , 1% u1 1 fairchild fan1084t 4.5a regulator item quantity manufacturer part number description c1 1 xicon l10v10 10f, 10v aluminum c3 1 xicon l10v100 100f, 10v aluminum u1 1 fairchild fan1084t-1.5 4.5a regulator fan1084 adj c3 100 f c2 100 f v out 2.5v + c1 10 f + + in out u1 v in r1 124 ? r2 124 ? rc1084-1.5 u1 gnd c3 100 f v out 1.5v + c1 10 f + in out v in = 3.3v
fan1084 product specification 7 rev. 1.0.3 9/24/01 mechanical dimensions 3-lead to-263 center cut package a .160 .190 4.06 4.83 symbol inches min. max. min. max. millimeters notes b .020 .036 0.51 0.91 b2 .049 .051 1.25 1.30 c2 .045 .055 1.14 1.40 d .340 .380 8.64 9.65 .380 .405 9.65 10.29 .100 bsc e e l .575 .625 14.61 15.88 .090 .110 2.29 2.79 .050 .070 1.27 1.78 l1 l2 l3 .055 1.40 .017 .019 0.43 0.78 r 0 8 0 8 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 surface (at inner r). 4. dimensiuon exclusive of dambar protrusion or intrusion. 5. formed leads to be planar with respect to one another at seating place -c-. 2.54 bsc e @pkg/ @heatsink d l2 l3 a -c- l c2 l1 r (2 plcs) -a- -b- e-pin b2 b e
fan1084 product specification 8 rev. 1.0.3 9/24/01 mechanical dimensions (continued) 3-lead to-220 package a .140 .190 3.56 4.83 symbol inches min. max. min. max. millimeters notes b .015 .040 .38 1.02 .070 1.78 b1 .045 1.14 c1 .014 .022 .36 .56 p .139 .161 3.53 4.09 d .560 .650 14.22 16.51 .380 .420 9.65 10.67 .090 .110 2.29 2.79 e e e1 .190 .210 4.83 5.33 .045 1.14 .020 .055 .51 1.40 e3 f h1 .230 .270 5.94 6.87 .080 .115 2.04 2.92 .500 .580 12.70 14.73 j1 l 6.35 bsc .250 bsc l1 .100 .135 2.54 3.43 3 7 3 7 q b1 b e3 l1 l h1 q e e e1 e-pin p c1 j1 d f a (5x) notes: 1. dimension c1 apply for lead finish.
product specification fan1084 rev. 1.0.3 9/24/01 9 mechanical dimensions (continued) 3-lead to-252 package a .086 .094 2.19 2.39 symbol inches min. max. min. max. millimeters notes b .025 .035 0.64 0.89 .045 1.14 b2 .030 0.76 c .018 .024 0.46 0.61 c2 .018 .023 0.46 0.58 d .210 .245 5.33 6.22 1 4 1 4 3 e .250 .265 6.35 6.73 .090 bsc 2.29 bsc .108 ref 2.74 ref .370 .410 9.40 10.41 e h l .055 .070 1.40 1.78 l1 .035 .080 0.89 2.03 .025 .040 0.64 1.02 .215 5.46 b3 .205 5.21 l3 l4 e b3 @pkg/ @heatsink d l3 a -c- h c2 l l1 -a- = 0 10 -b- e-pin b2 l4 b e notes: 1. 2. 3. 4. 5. 6. dimensions are exclusive of mold flash, metal burrs or interlead protrusion. stand off-height is measured from lead tip with ref. to datum -b-. foot length is measured with ref. to datum -a- with lead surface. thermal pad contour optional within dimension b3 and l3. formed leads to be planar with respect to one another at seating place -c-. dimensions and tolerances per asme y14.5m-1994.
fan1084 product specification 9/24/01 0.0m 003 stock#ds30001084 ? 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 fan1084mc to-263 center cut fan1084t to-220 fan1084d to-252 fan1084mc-1.5 to-263 center cut fan1084t-1.5 to-220 fan1084d-1.5 to-252 fan1084mc-3.3 to-263 center cut fan1084t-3.3 to-220 fan1084d-3.3 to-252
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