RT2515A ? ds2515a-02 november 2012 www.richtek.com 1 copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. ? ordering information note : richtek products are : ` rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ` suitable for use in snpb or pb-free soldering processes. pin configurations 2a, low input voltage, ultra-low dropout linear regulator with enable (top view) sop-8 (exposed pad) general description the RT2515A is a high performance positive voltage regulator desi gned for use in applications requiring ultra- low input voltage and ultra-low dropout voltage at up to 2 amperes. it operates with an input voltage as low as 1.4v, with output voltage programmable as low a s 0.5v. the RT2515A features ultra low dropout, ideal for applications where output voltage is very close to input voltage. additionally, the RT2515A has an enable pin to further reduce power dissipation while shutdown. the RT2515A provides excellent regulation over variations in line, load and temperature. the RT2515A is available in the sop-8 (exposed pad) package. the output voltage can be set by an external divider or fixed at 1.2v depending on how the fb pin is configured. features z z z z z input voltage as low as 1.4v z z z z z ultra-low dropout voltage 400mv @ 2a z z z z z adjustable output voltage from 0.5v to 3.8v z z z z z over current protection z z z z z over temperature protection z z z z z 1 a input current in shutdown mode z z z z z enable control z z z z z rohs compliant and halogen free applications z telecom/networking cards z motherboards/peripheral cards z industrial applications z wireless infrastructure z set top box z medical equipment z notebook computers z battery powered systems nc en vin nc gnd adj nc vout gnd 2 3 4 5 6 7 8 9 marking information RT2515A lead plating system g : green (halogen free and pb free) package type sp : sop-8 (exposed pad-option 2) RT2515A gspymdnn RT2515Agsp : product number ymdnn : date code
RT2515A 2 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. functional pin description function block diagram pin no. pin name pin function 1, 4, 5 nc no internal connection. 2 en chip enable (active-high). pulling this pin below 0.4v turns the regulator off, reducing the quiescent current to a fraction of its operating value. the device will be enabled if this pin is left open. connect to vin if not being used. 3 vin input voltage. for regulation at full load, the input to this pin must be between (v out + 0.5v) and 5.5v. minimum input voltage is 1.4v. a large bulk capacitance should be placed closely to this pin to ensure that the input supply does not sag below 1.4v. also a minimum of 10 f ceramic capacitor should be placed directly at this pin. 6 vout output voltage. a minimum of 10 f capacitor should be placed directly at this pin. 7 ad j when this pin is grounded, an internal resistor divider sets the output voltage to 1.2v. if connected to the vout pin, the output voltage will be set at 0.5v. if external feedback resistors are used, the output voltage will be determined by the resistor ratio. 8, 9 (exposed pad) gnd ground. the exposed pad must be soldered to a large pcb and connected to gnd for maximum power dissipation. typical application circuit figure 2. fixed voltage regulator figure 1. adjustable voltage regulator en adj vout RT2515A gnd vin v in 10f v out 10f c2 r1 r2 out 0.5(r1+r2) v = (v) r2 6 7 c1 3 chip enable 2 8, 9 (exposed pad) en adj vout RT2515A gnd vin v in 10f v out 10f c2 6 7 c1 3 chip enable 2 8, 9 (exposed pad) 1.2v + - + - reference generator 0.5v 0.1v thermal shutdown 0.5a v in v pump - + r sense en vin gnd adj vout mode select v in + - v in v out reverse voltage shutdown
RT2515A 3 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. electrical characteristics (v in = 1.4v to 6v, i out = 10 a to 2a, v adj = v out , ? 40 c t a 85 c, unless otherwise specified) parameter symbol test conditions min typ max unit quiescent current i q v in = 3.3v, i out = 0a -- 0.7 1.5 ma shutdown current i shdn v in = 5.5v, v en = 0v -- 1.5 10 a v in = v out + 0.5v, i out = 10ma t a = 25 c v in = 1.8v, i out = 0.8a, t a = 25 c ? 2 -- 2 output voltage (fixed output, v adj = 0v) v out 1.4v v in 5.5v, i out = 10ma ? 3 -- 3 % line regulation v line i out = 10ma -- 0.2 0.4 %/v load regulation v load i out = 10ma to 2a -- 0.5 1.5 % i out = 1a, v in 1.6v -- 120 200 i out = 1a, 1.4v < v in < 1.6v -- -- 400 i out = 1.5a, v in 1.6v -- 180 300 i out = 1.5a, 1.4v < v in < 1.6v -- -- 500 i out = 2a, v in 1.6v -- 240 400 dropout voltage v drop i out = 2a, 1.4v < v in < 1.6v -- -- 600 mv current limit i lim v in = 3.3v 2.3 3 4.4 a absolute maximum ratings (note 1) z supply voltage, vin ------------------------------------------------------------------------------------------------------ ? 0.3v to 7v z other i/o pin --------------------------------------------------------------------------------------------------------------- ? 0.3v to 6v z power dissipation, p d @ t a = 25 c sop-8 (exposed pad) --------------------------------------------------------------------------------------------------- 2.04w z package thermal resistance (note 2) sop-8 (exposed pad), ja ---------------------------------------------------------------------------------------------- 49 c/w sop-8 (exposed pad), jc --------------------------------------------------------------------------------------------- 15 c/w z lead temperature (soldering, 10 sec.) ------------------------------------------------------------------------------- 260 c z junction temperature ----------------------------------------------------------------------------------------------------- 150 c z storage temperature range -------------------------------------------------------------------------------------------- ? 65 c to 150 c z esd susceptibility (note 3) hbm (human body model) ---------------------------------------------------------------------------------------------- 2kv recommended operating conditions (note 4) z supply voltage, vin ------------------------------------------------------------------------------------------------------ 1.4v t o 6v z junction temperature range -------------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range -------------------------------------------------------------------------------------------- ? 40 c to 85 c
RT2515A 4 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. note 1. stresses beyond those listed ? absolute maximum ratings ? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions may affect device reliability. note 2. ja is measured at t a = 25 c on a high effective thermal conductivity four-layer test board per jedec 51-7. jc is measured at the exposed pad of the package. note 3. devices are esd sensitive. handling precaution is recommended. note 4. the device is not guaranteed to function outside its operating conditions. parameter symbol test conditions min typ max unit feedback v in = 3.3v, v adj = v out , i out = 10ma, t a = 25 c 0.495 -- 0.505 adj reference voltage v adj v in = 3.3v, v adj = v out , i out = 10ma 0.49 -- 0.51 v adj pin current i adj v adj = 0.5v -- 20 200 na adj pin threshold v th_adj v in = 3.3v 0.05 0.1 0.15 v enable en pin current i en v en = 0v, v in = 5.5v -- 1 10 a logic-high v ih v in = 3.3v 1.6 -- -- en threshold voltage logic-low v il v in = 3.3v -- -- 0.4 v over temperature protection otp trip level -- 160 -- c hysteresis -- 30 -- c
RT2515A 5 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. typical operating characteristics quiescent current vs. temperature 0.35 0.55 0.75 0.95 1.15 -50-25 0 25 50 75100125 temperature (c) quiescent current (ma ) v in = 3.3v v in = 5v v out = 2.52v uvlo vs. temperature 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 -50-25 0 25 50 75100125 temperature (c) uvlo (v) v en = 5v logic-low logic-high shutdown current vs. temperature 0.30 0.45 0.60 0.75 0.90 1.05 1.20 -50-25 0 25 50 75100125 temperature (c) shutdown current (a) 1 v in = 3.3v v in = 5v en threshold voltage vs. temperature 0.7 0.8 0.9 1.0 1.1 1.2 1.3 -50 -25 0 25 50 75 100 125 temperature (c) en threshold voltage (v ) v in = 5v logic-low logic-high dropout voltage vs. load current 0 50 100 150 200 250 300 350 00.511.52 load current (a) dropout voltage (mv) v out = 2.5v 125 c 25 c ? 40 c reference voltage vs. temperature 0.480 0.485 0.490 0.495 0.500 0.505 0.510 0.515 0.520 -50-25 0 255075100125 temperature (c) reference voltage (v) v in = 3.3v v in = 5v
RT2515A 6 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. load transient response time (50 s/div) v in = 3.3v, v out = 2.5v, i out = 1a to 2a i out (1a/div) v out (20mv/div) line transient response time (500 s/div) v out (10mv/div) v in (1v/div) v in = 3.3v to 4.3v, v out = 2.5v, i out = 2a psrr -80 -70 -60 -50 -40 -30 -20 -10 0 100 1000 10000 100000 1000000 frequency (hz) psrr (db) v in = 3.25v to 3.35v, v out = 2.5v i out = 1ma i out = 100ma i out = 300ma power on from en time (250 s/div) v in = 3.3v, v out = 2.5v, i out = 2a v en (5v/div) i in (2a/div) v out (2v/div) power off from en time (250 s/div) v en (5v/div) i in (2a/div) v out (2v/div) v in = 3.3v, v out = 2.5v, i out = 2a
RT2515A 7 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. application information the RT2515A is a low voltage, low dropout linear regulator with an external bias supply input capable of supporting an input voltage range from 1.4v to 6v with a fixed output voltage from 1v to 2v in 0.1v increments. output voltage setting the RT2515A output voltage is adjustable from 1.4v to 6v via the external resistive voltage divider. the voltage divider resistors can have values of up to 800k because of the very high impedance and low bias current of the sense comparator. the output voltage is set according to the following equation : out adj r1 v = v 1+ r2 ?? ?? ?? where v adj is the reference voltage with a typical value of 0.5v. chip enable operation the RT2515A goes into sleep mode when the en pin is in a logic low condition. in this condition, the pass transistor, error amplifier, and band gap are all turned off, reducing the supply current to only 10 a (max.). the en pin can be directly tied to vin to keep the part on. current limit the RT2515A contains an independent current limit circuitry, which monitors and controls the pass transistor's gate voltage, limiting the output current to 3a (typ.). c in and c out selection like any low dropout regulator, the external capacitors of the RT2515A must be carefully selected for regulator stability and performance. using a capacitor of at least 10 f is suitable. the input capacitor must be located at a distance of not more than 0.5 inch from the input pin of the ic. any good quality ceramic capacitor can be used. however, a capacitor with larger value and lower esr (equivalent series resistance) is recommended since it will provide better psrr and line transient response. the RT2515A is designed specifically to work with low esr ceramic output capacitor for space saving and performance consideration. using a ceramic capacitor with capacitance of at least 10 f and esr larger than 1m on the RT2515A output ensures stability. nevertheless, the RT2515A can still work well with other types of output capacitors due to its wide range of stable esr. figure 3 shows the allowable esr range as a function of load current for various output capacitance. output capacitors with larger capacitance can reduce noise and improve load transient response, stability, and psrr. the output capacitor should be located at a distance of not more than 0.5 inch from the output pin of the RT2515A. figure 3 thermal considerations thermal protection limits power dissipation in RT2515A. when the operation junction temperature exceeds 160 c, the otp circuit starts the thermal shutdown function and turns the pass element off. the pass element turns on again after the junction temperature cools by 30 c. RT2515A output voltage will be closed to zero when output short circuit occurs as shown in figure 4. it can reduce the ic temperature and provides maximum safety to end users when output short circuit occurs. region of stable c out esr vs. load current 0.001 0.01 0.1 1 10 100 0.0 0.3 0.5 0.8 1.0 load current (a) c out esr ( ) v in = 3.3v, v out = 2.5v, c out = 10 f / x7r unstable range stable range
RT2515A 8 ds2515a-02 november 2012 www.richtek.com ? copyright 2012 richtek technology corporation. all rights reserved. is a registered trademark of ric htek technology corporation. figure 5. derating curve of maximum power dissipation for continuous operation, do not exceed absolute maximum junction temperature. the maximum power dissipation depends on the thermal resistance of the ic package, pcb layout, rate of surrounding airflow, and difference between junction and ambient temperature. the maximum power dissipation can be calculated by the following formula : p d(max) = (t j(max) ? t a ) / ja where t j(max) is the maximum junction temperature, t a is the ambient temperature, and ja is the junction to ambient thermal resistance. for recommended operating condition specifications, the maximum junction temperature is 125 c. the junction to ambient thermal resistance, ja , is layout dependent. for sop-8 (exposed pad) package, the thermal resistance, ja , is 49 c/w on a standard jedec 51-7 four-layer thermal test board. the maximum power dissipation at t a = 25 c can be calculated by the following formula : p d(max) = (125 c ? 25 c) / 49 c/w) = 2.04w for sop-8 (exposed pad) package the maximum power dissipation depends on the operating ambient temperature for fixed t j(max) and thermal resistance, ja . the derating curve in figure 5 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. figure 4. short circuit protection when output short circuit occurs v out short to gnd v out i out ic temperature i lim i lim 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 0 25 50 75 100 125 ambient temperature (c) maximum power dissipation (w ) four-layer pcb
RT2515A 9 ds2515a-02 november 2012 www.richtek.com richtek technology corporation 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 richtek products are sold by description only. richtek reserves the right to change the circuitry and/or specifications without notice at any time. customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a richtek product. information furnish ed by richtek is believed to be accurate and reliable. however, no responsibility is assumed by richtek or its subsidiaries for its use; nor for any infringeme nts of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of r ichtek or its subsidiaries. outline dimension a b j f h m c d i y x exposed thermal pad (bottom of package) 8-lead sop (exposed pad) plastic package dimensions in millimeters dimensions in inches symbol min max min max a 4.801 5.004 0.189 0.197 b 3.810 4.000 0.150 0.157 c 1.346 1.753 0.053 0.069 d 0.330 0.510 0.013 0.020 f 1.194 1.346 0.047 0.053 h 0.170 0.254 0.007 0.010 i 0.000 0.152 0.000 0.006 j 5.791 6.200 0.228 0.244 m 0.406 1.270 0.016 0.050 x 2.000 2.300 0.079 0.091 option 1 y 2.000 2.300 0.079 0.091 x 2.100 2.500 0.083 0.098 option 2 y 3.000 3.500 0.118 0.138
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