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rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 1 9/4/2012 se 1084 5a low dropout linear regulator typica l application general d escription se 1084 is a low dropout positive adjustable or fixed - mode regulator with minimum of 5.0a output current capability. the prod uct is specifically designed to provide well - regulated supply for low voltage ic applications such as high - speed bus termination and low current 3.3v logic supply. se 1084 is also well suited for other applications such as vga cards. se 1084 is guaranteed to have lower than 1.5v dropout at full load current making it ideal to provide well - regulated outputs of 1.25vto 3.3v with 4.8vto 12v input supply. featur es ? 5v maximum dropout at full load current ? built - in thermal shutdown ? output current limiting ? adjustab le and1.5v/1.8v/2.5v/3.3v/5.0v fixed output voltages ? fast transient response ? good noise rejection ? package: to252, to263, to220 applicatio ns ? high efficiency linear regulators ? battery chargers ? post regulation for switching supply ? microprocessor supply ? des ktop pcs, risc and embedded processors' supply
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 2 9/4/2012 se 1084 5a low dropout linear regulator pi n configuration to252:1 adj(gnd) 2 vout 3 vin to2 63 :1 adj(gnd) 2 vout 3 vin to2 20 :1 adj(gnd) 2 vout 3 vin pi n description no. pin name pin function description 1 adj (gnd) adjustable (ground only for fixed version) a resistor divider from this pin to the v out pin and ground sets the output voltage. 2 v out the output of the regulator. a minimum of 100uf (0.15 esr 10) ca pacitor must be connected from this pin to ground to insure stability. 3 v in the input pin of regulator. typically a large storage capacitor (0.15 esr 10) is connected from this pin to ground to insure that the input voltage does not sag below the min imum dropout voltage during the load transient response. this pin must always be 1.4v higher than v out in order for the device to regulate properly. functiona l block diagram
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 3 9/4/2012 se 1084 5a low dropout linear regulator ord er in g information part number marking information package remarks SE1084j - lf SE1084j yyww - lf to252 yyww means production batch adjustable output voltage. SE1084r - lf SE1084r yyww - lf to263 SE1084q - lf SE1084q yyww - lf to220 SE1084jxx - lf SE1084jxx yyww - lf to252 yyww means production batch fixed output voltages; xx denotes voltage options ( 1.5v, 1.8v, 2.5v , 3.3v and 5.0v ). SE1084rxx - lf SE1084r xx yyww - lf to263 SE1084qxx - lf SE1084q xx yyww - lf to220 absolut e maximum ratings symbol parameter maximum units v in dc supply voltage - 0.3 to 12 v p d power dissipation internally limited t st storage temperature - 65 to +150 t opj operating junction temperature range - 40to +125
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 4 9/4/2012 se 1084 5a low dropout linear regulator e lectrica l c haracteristics v in = 3.6 v ; tj=25 unless otherwise specified s ymbol characteristics t est c onditions m in t yp m ax u nit v ref reference voltage i out =10ma, t j =25 , (v in -v out )=1.5v 1.225 1.250 1.275 v v out output voltage (fixed version) i out = 10ma, t j = 25 , 3v Qv in Q12v 1.470 1.500 1.530 v i out = 10ma, t j = 25 , 3.3v Qv in Q12v 1.764 1.800 1.836 v i out = 10ma, t j = 25 , 4v Qv in Q12v 2.450 2.500 2.550 v i out = 10ma, t j = 25 , 4.8v Qv in Q12v 3.2 35 3.300 3.365 v i out = 10ma, t j = 25 , 6.5v Qv in Q12v 4.900 5.000 5.100 v v line line regulation i out =10ma, v out +1.5v rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 5 9/4/2012 se 1084 5a low dropout linear regulator v in =6.5v,10ma>10mm*5.5mm (like 10mm*10mm).
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 6 9/4/2012 se 1084 5a low dropout linear regulator typica l performance characteristics
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 7 9/4/2012 se 1084 5a low dropout linear regulator applications information introduction the SE1084 adjustabl e low dropout (ldo) regulator is a 3 terminal device that can easily be programmed with the addition of two external resistors to any voltages within the range of 1.25v to v in - 1.5v. the SE1084 only needs 1.5v differential between v in and v out to maintain o utput regulation. in addition, the output voltage tolerances are also extremely tight and they include the transient response as part of the specification. for example, intel vre specification calls for a total of +/ - 100mv including initial t o lerance, load regulation and 0 to 5.0a load step. the SE1084 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 output capacitors. output voltage setting the SE1084 can be programmed to any voltages in the range of 1.25v to v in - 1.5v with the addition of r1 and r2 external resistors according to the following formula: v out = v ref (1+ r2/r1) +iadj *r2 , where v ref = 1.25 typically, iadj = 50ua typical ly r1 and r2 as shown at below the SE1084 keeps a constant 1.25v between the output pin and the adjust pin. by placing a resistor r1 across these two pins a constant current flows through r1, adding to the iadj current and into the r2 r esistor producing a voltage equal to the (1.25/r1)*r2+iadj*r2 which will be 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 SE1084 is 10ma, r1 is typically selected to be 121 resistor so that it automatically satisfies the minimum current requirement. notice that since iadj is typically in the range of 50ua it only adds a small error to the output voltage and should only be consider ed when a very precise output voltage setting is required. for example, in a typical 3.3v application where r1=121 and r2=200 the error due to iadj is only 0.3% of the nominal set point. load regulation since the SE1084 is only a 3 terminal device, it i s not possible to provide true remote sensing of the output voltage at the load. the best load regulation is achieved when the bottom side of r2 is connected to the load and the top - side of r1 resistor is connected directly to the case or the v out pin of t he regulator and not to the load. it is important to note that for high current applications, this can re - present a significant percentage of the overall load regulation and one must keep the path from the regulator to the load as short as possible to mini mize this effect.
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 8 9/4/2012 se 1084 5a low dropout linear regulator stability the SE1084 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. for most applications a minimum of 100uf aluminum electrolytic capacitor insures both stability a nd good transient response. thermal design the SE1084 incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the maximum allowable junction temperature. although this device can operate with junction tempe ratures in the range of 150 , it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the junction temperature is kept below the temperature. layout consideration the output capacitors must be located as close to the v out terminal of the device as possible. it is recommended to use a section of a layer of the pc board as a plane to connect the v out pin to the output capacitors to prevent any high frequency oscillation that may result due to excessive trace inductance.
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 9 9/4/2012 se 1084 5a low dropout linear regulator outlin e drawing for SE1084 (1) to252
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 10 9/4/2012 se 1084 5a low dropout linear regulator (2) to263
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 11 9/4/2012 se 1084 5a low dropout linear regulator (3) to220
rev 1.0 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., ? www.seawardinc.com ? page 12 9/4/2012 se 1084 5a low dropout linear regulator ?? ???? ? ? ??? 22 ???? b ?? 100085 : 0 10- 82895700/1/5 : 0 10- 82895706 seaward electronics corporation ? ? 2f, #181, se c. 3, minquan east rd, taipei, taiwan r.o.c : 886- 2 - 2712 - 0307 : 886- 2 - 2712 - 0191 seaward electronics incorporated ? 1512 centre pointe dr. milpitas, ca95035, usa : 1 - 408 - 821 - 6600

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