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www.fairchildsemi.com rev. 0.1.6 8/30/04 features 1.5a minimum guaranteed output current 500mv maximum dropout at 1.5a ideal for 2.5v to 1.8v or 1.65v conversion ideal for 3.0v to 2.5v conversion current limiting and thermal shutdown external shut-down control (fan1951 only) error ?g output (fan1951 only) ? ast transient response ? ow ground current applications general purpose conversion for low-voltage cpus, dsp and fpgas smps post regulator cable/satellite set-top boxes pci graphics adapter cards general description the fan1950 and fan1951 are 1.5a low-dropout linear regulators that provide a low voltage, high current output with a minimum of external components. both of these devices use a pnp output pass element achieving a maxi- mum 500mv dropout at 1.5a load current. in addition these devices offer overcurrent limit and thermal shutdown features to ensure full protection. the fan1951 offers a logic level enable pin and an error ?g output to indicate undervoltage and over-current condi- tions. 1.8v and 2.5v ?ed output versions are available. 3.3v, 1.65v and 1.5v options are available upon request. t ypical application 3.0v 2.5v 100k ? 2.5v 1.8v fan1950-2.5v fan1951-1.8v 10 f10 f in in flag en error output on/off out out gnd gnd f an1950/fan1951 1.5a low-voltage low-dropout regulator
fan1950/fan1951 2 rev. 0.1.6 8/30/04 pin assignments pin descriptions pin number pin name pin function description f an1950 fan1951 na 1 en enable (input) ?ttl/cmos compatible input. logic high enables the output 1 2 in input supply voltage 2 3 gnd ground. this pin and tab are ground. 3 4 out output voltage na 5 flag error flag (output). open-collector output. active-low indicates an output fault condition. front view fan1951dx front view fan1950dx 5-lead plastic to-252 (dpak) 3-lead plastic to-252 (dpak) in out gnd (tab) en flag gnd (tab) out in 1 2 3 4 5 1 2 3
fan1950/fan1951 rev. 0.1.6 8/30/04 3 absolute maximum ratings absolute maximum ratings are the values beyond which the device may be damaged or have its useful life impaired. functional operation under these conditions is not implied. recommended operating conditions electrical speci?ations (v in = v out + 1v, v en = 2.5v, t j = +25? unless speci?d otherwise) the ?denotes speci?ations which apply over the full operating temperature range. p arameter min. typ. max. units supply voltage: in -0.2 15 v enable voltage: en -0.2 15 v flag voltage: flag -0.2 15 v junction temperature (t j ) ?5 150 ? storage temperature ?5 150 ? lead soldering temperature, 10 seconds 300 ? power dissipation (p d ) internally limited w p arameter conditions min. typ. max. units supply voltage 2.25 14 v package thermal resistance ( jc )t o-252 3 c/w junction operating temperature -40 125 c p arameter conditions min. typ. max. units output voltage (v out ) tolerance 10ma i out 1.0a, 10ma i out 1.5a, v out + 1v v in 8v -2 -2.5 2 2.5 % line regulation 1,2 i out = 10ma, v out + 1v v in 14v .06 0.5 % load regulation 1,2 v in = v out + 1v, 10ma i out 1.5a 0.2 1 % dropout voltage 3 i out = 1.5a, ? v out = -1% 350 500 mv ground current i out = 750ma i out = 1.5a ?0 20 20 ma ma minimum load current v out + 1v v in 8v 5 10 ma current limit v out = 0v, v in = v out + 1v 2.5 a en input voltage (fan1951 only) v ih (on) v il (off) 2.25 0.8 v v en input current (fan1951 only) i ih , v en = 2.25v i il , v en = 0.8v 30 4 ? ? flag threshold voltage (fan1951 only) low threshold, % v out high threshold, % v out hysteresis 93 1 99.2 % % % flag output leakage current 4 (fan1951 only) v flag = 14v 2 ? flag output-low voltage (fan1951 only) i ol = 250? 400 mv
fan1950/fan1951 4 rev. 0.1.6 8/30/04 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 current. guaranteed maximum output power will not be available over the full input/output voltage range. 3. dropout voltage = v in ?v out when v out decreases to 98% 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. 4. flag output cannot be pulled to a voltage higher than v in . thermal shutdown temperature 150 ? thermal shutdown hysteresis 10 ? shutdown output current v en 0.8v, v in 8v, v out = 0v 20 a p arameter conditions min. typ. max. units
fan1950/fan1951 rev. 0.1.6 8/30/04 5 t ypical performance characteristics dropout voltage vs. output current 0 0.5 0.7 0.9 1.1 1.3 1.5 0.1 0.2 0.3 0.4 0.5 0.6 load current (a) dropout (v) -40 c -10 c +25 c +75 c +125 c dropout voltage vs. temperature 0 0.1 0.2 0.3 0.4 0.5 0.6 -50 0 50 100 150 tj dropout (v) il = 1a il = 1.5a vout = 2.5v, 1.8v, iout = 1a, 1.5a iout = 10ma ground current vs. supply voltage vin = vout + 1v, 25 c 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0510 15 20 vin (v) ground current (ma) (v) ground current vs. load current vin = vout + 1v, 25 c 0.00 5.00 10.00 15.00 20.00 25.00 0 500 1000 1500 2000 load current (ma) ground current (ma) i gnd (ma)
fan1950/fan1951 6 rev. 0.1.6 8/30/04 t ypical performance characteristics (continued) vin = 3v, vout = 1.8v ch.1 ?vout (1v/div) ch.2 ?load current (2a/div) fan1950d18 short-circuit transient response vin = 3v, vout = 1.8v ch.1 ?vout (1v/div) ch.2 ?load current (2a/div) fan1950d25 short-circuit transient response fan1950d25 short-circuit recovery response ground current vs. temperature vin = 3v 0.00 5.00 10.00 15.00 20.00 25.00 30.00 -50 0 50 100 150 temperature (c) ground current (ma) ignd_@10ma ignd @ 750ma ignd_ @ 1.5a vin = 3v, vout = 2.5v ch.1 ?vout (1v/div) ch.2 ?load current (2a/div) vin = 3v, vout = 2.5v ch.1 ?vout (1v/div) ch.2 ?load current (2a/div) fan1950d18 short-circuit recovery response
fan1950/fan1951 rev. 0.1.6 8/30/04 7 t ypical performance characteristics (continued) vout vs. temperature ( c) 2.450 2.475 2.500 2.525 2.550 -50 -25 0 50 100 150 125 75 25 (10 ma load) junction temperature ( c) iout = 10 ma; vout = 2.5v vout (v) fan1950d25 ripple rejection (psrr) vin = 5v vout = 2.5v iload = 1a cin = cout = 10 f/ 6.3v tantalum psrr ?10db/div fan1950d18 ripple rejection (psrr) vin = 3v and 5v vout = 1.8v iload = 1a cin = cout = 10 f/ 6.3v tantalum psrr ?10db/div load transient response vin=2.5v, vout=1.8v, cin=10 f ceramic cout = 10 f tantalum (esr~700m ? ) ch1 ?vout (ac, 0.5v/div) ch2 ?load current (1a/div.) load transient response vin=2.5v, vout=1.8v, cin=10 f ceramic cout = 10 f ceramic ch1 ?vout (ac, 0.5v/div.) ch2 ?load current (1a/div.) vin = 5v vin = 3v vout vs. temperature 1.764 1.774 1.784 1.794 1.804 1.814 1.824 1.834 -100 -50 0 50 100 150 junction temperature ( c) iout = 10 ma; vout = 1.8v vout (v)
fan1950/fan1951 8 rev. 0.1.6 8/30/04 input and output capacitor requirements a 4.7? or greater input capacitor (ceramic or tanta- lum), installed closely between v in and gnd leads of the part, is required for stability, better transient response, noise and ripple rejection. a higher value of electrolytic input capacitor can be recommended if the b ulk capacitor of the power supply is located more than 3?4 inches from the device or a large and fast-rise- time load is a requirement. f an1950 and fan1951, as most of ldo regulators, require an output capacitor. the recommended value of this capacitor is 10?. the larger capacitor will additionally improve the transient response, ripple rejection and output noise. the low-esr tantalum capacitors are the best for this application: they provide stable work and good transient response over the tem- perature range. using the ceramic capacitors as the output capacitor can provoke instability (oscillation in the output voltage). aluminum electrolytic capacitors also can be used if their esr is below 3 ? .
fan1950/fan1951 rev. 0.1.6 8/30/04 9 mechanical dimensions 5-lead to-252 dpak 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
fan1950/fan1951 10 rev. 0.1.6 8/30/04 mechanical dimensions 3-lead to-252 dpak package d d1 gage plane notes: unless otherwise specified a) all dimensions are in millimeters. b) this package conforms to jedec, to-252, issue c. variation aa & ab, dated nov. 1999. c) dimensioning and tolerancing per asme y14.5?994. d) heat sink top edge could be in chamfered corners or edge protrusion. e) dimensions l3, d, e1 & d1 table: option aa option ab 0.89 ?1.27 1.52 ?2.03 5.97 ?6.22 5.33 ?5.59 4.32 min 3.81 min 5.21 min l3 d e1 d1 4.57 min 0.51 seating plane detail a (1.54) 1.78 1.40 0.61 0.46 10 0 0.127 max (rotated ?0 ) scale 12x e1 l3 1 1 2 3 1 2 3 4 3 4 6.73 6.35 1.02 0.64 6.25 6.00 min 6.50 min 4.60 2.39 2.18 0.58 0.46 0.10 b 10.41 9.40 see detail a 3.00 min 1.40 min land pattern recommendation 1.14 0.76 0.89 0.64 see note d (0.59) 2.29 5.46 5.21 4.57 0.25 a c mm (2.90) 2.30 c a b
fan1950/fan1951 8/30/04 0.0m 005 stock#ds30001950 ? 2003 fairchild semiconductor corporation life support policy fairchild? 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 note: please contact sales for other voltage and package options. pa rt number output voltage package f an1951d18x 1.8v 5 lead to-252 dpak in tape and reel f an1951d25x 2.5v 5 lead to-252 dpak in tape and reel f an1950d25x 2.5v 3 lead to-252 dpak in tape and reel

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