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rt9018a/b 1 ds9018a/b-04 september 2007 www.richtek.com pin configurations maximum 3a, ultra low dropout regulator ordering information features z z z z z maximum 3a low-dropout voltage regulator z z z z z high accuracy output voltage 1.5% z z z z z typically 220mv dropout at 3a z z z z z power good output z z z z z output voltage pull low resistance when disable z z z z z thermal and over current protection z z z z z rohs compliant and 100% lead (pb)-free applications z front side bus vtt (1.2v/3a) z notebook pc applications z motherboard applications marking information for marking information, contact our sales representative directly or through a richtek distributor located in your area, otherwise visit our website for detail. (top view) wdfn-10l 3x3 general description the rt9018a/b is a high performance positive voltage regulator designed for use in applications requiring very low input voltage and very low dropout voltage at up to 3a(peak). it operates with a vin as low as 1.0v and vdd voltage 3v with output voltage programmable as low as 0.8v. the significant feature includes ultra low dropout, ideal for applications where vout is very close to vin. additionally, there is an enable pin to further reduce power dissipation while shutdown. the rt9018a/b provides excellent regulation over variations in line, load and temperature. and provides a power ok signal to indicate if the voltage level of vo reaches 90% of its rating value. the rt9018a/b is available in the sop-8 (exposed pad) and wdfn-10l 3x3 packages with 1v, 1.05v, 1. 2v, 1.5v, 1.8v and 2.5v internally preset outputs that are also adjustable using external resistors. note : richtek pb-free and green 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. ` 100% matte tin (sn) plating. sop-8 (exposed pad) rt9018a/b package type sp : sop-8 (exposed pad-option 1) qw : wdfn-10l 3x3 enable pin function a : internal pull high b : internal pull low output voltage 10 : 1v/adj 1k : 1.05v/adj 12 : 1.2v/adj 15 : 1.5v/adj 18 : 1.8v/adj 25 : 2.5v/adj operating temperature range p : pb free with commercial standard g : green (halogen free with commer- cial standard) vout vout pgood adj vdd vin vin en vin vout 9 8 7 9 1 2 3 4 5 10 gnd 11 pgood en vin vdd gnd adj nc vout gnd 2 3 4 5 6 7 8 9
rt9018a/b 2 ds9018a/b-04 september 2007 www.richtek.com function block diagram typical application circuit pin description pin no. pi n name pi n function psop-8 wdfn 3x3 3 7, 8, 9 vin supply input voltage. 2 6 en ch ip ena ble (active-high). 4 10 vdd supply voltage of control circuitry. 1 5 pgood power good open drain output. 7 4 adj set the output voltage by the internal feedback resistors when adj is grounded. if external feedback resistors is used, v out = 0.8v x (r1 + r2)/r2. 6 1, 2, 3 vout output voltage. 5 -- nc no internal connection. 8, ex p osed pad ( 9 ) exposed pad (11) gn d ground. the exposed pad must be soldered to a large pcb and connected to gnd for maximum p ower dissi p ation. figure 1. fixed voltage regulator figure 2. adjustable voltage regulator r2 r2 r1 0.8 v out + = vin en gnd vout adj pgood rt9018a/b v out 10uf 10uf chip enable 100k v out vdd 1uf v dd v in ocp error amplifier por en gnd adj vin pgood vout vdd mode + - + - 0.8v 0.72v driver otp vin en gnd vout adj pgood rt9018a/b v out 10uf 10uf chip enable r1 r2 100k v out vdd 1uf v dd v in c dummy
rt9018a/b 3 ds9018a/b-04 september 2007 www.richtek.com electrical characteristics (v in = v out + 500mv, v en = v dd = 5v, c in = c out = 10uf, t a = t j = 25 c, unless otherwise specified) parameter symbol test conditions min typ max units vdd operation voltage range v dd v dd input range 3.6 -- 5.5 v por threshold 2.4 2.7 3 v por hysteresis 0.15 0.2 -- v adjustable pin threshold v th_adj i out = 1ma -- 0.2 0.4 v reference voltage (adj pin voltage) v adj i out = 1ma 0.788 0.8 0.812 v fixed output voltage range v out ? 1.5 0 +1.5 % line regulation (v in ) v line_in v in = v out + 0.5v to 5v, i out = 1ma -- 0.2 0.6 % load regulation (note 7) v load v in = v out + 1v, i out = 1ma to 3a -- 0.2 1 % i out = 2a -- 150 250 mv dropout voltage (note 5) v drop i out = 3a -- 210 350 mv quiescent current (note 6) i q v dd = 5.5v -- 0.6 1.2 ma current limit i lim 3.2 4.5 -- a short circuit current v out < 0.2v 0.5 1.8 -- a in-rush current c out = 10uf, enable start-up -- 0.6 -- a v out pull low resistance v en = 0v -- 150 -- to be continued recommended operating conditions (note 3) z supply voltage, v in --------------------------------------------------------------------------------------------------- 1.4v to 5.5v z control voltage, v dd -------------------------------------------------------------------------------------------------- 3.6v to 5.5v z junction temperature range ---------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range ---------------------------------------------------------------------------------------- ? 40 c to 85 c absolute maximum ratings (note 1) z supply voltage, v in --------------------------------------------------------------------------------------------------- 1v to 6v z control voltage, v dd -------------------------------------------------------------------------------------------------- 3v to 6v z output voltage, v out ------------------------------------------------------------------------------------------------- 0.8 to 6v z power dissipation, p d @ t a = 25 c sop-8 (exposed pad) ----------------------------------------------------------------------------------------------- 1.33w wdfn-10l 3x3 --------------------------------------------------------------------------------------------------------- 1.67w z package thermal resistance (note 4) sop-8 (exposed pad), ja ------------------------------------------------------------------------------------------ 75 c/w sop-8 (exposed pad), jc ----------------------------------------------------------------------------------------- 15 c/w wdfn-10l 3x3, ja --------------------------------------------------------------------------------------------------- 60 c/w z junction temperature ------------------------------------------------------------------------------------------------- 150 c z lead temperature (soldering, 10 se c.) --------------------------------------------------------------------------- 260 c z storage temperature range ---------------------------------------------------------------------------------------- ? 65 c to 150 c z esd susceptibility (note 2) hbm (human body mode) ------------------------------------------------------------------------------------------ 2kv mm (ma chine mode) -------------------------------------------------------------------------------------------------- 200v
rt9018a/b 4 ds9018a/b-04 september 2007 www.richtek.com note 1. stresses listed as the above "absolute maximum ratings" may cause permanent damage to the device. these are for stress ratings. 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 for extended periods may remain possibility to affect device reliability. note 2. devices are esd sensitive. handling precaution recommended. note 3. the device is not guaranteed to function outside its operating conditions. note 4. ja is measured in the natural convection at t a = 25 c on a high effective thermal conductivity test board (4 layers, 2s2p) of jedec 51-7 thermal measurement standard. the case point of jc is on the expose pad for sop-8 (exposed pad) package. note 5. the dropout voltage is defined as v in -v out , which is measured when v out is v out(normal) - 100mv. note 6. quiescent, or ground current, is the difference between input and output currents. it is defined by i q = i in - i out under no load condition (i out = 0ma). the total current drawn from the supply is the sum of the load current plus the ground pin current. note 7. regulation is measured at constant junction temperature by using a 2ms current pulse. devices are tested for load regulation in the load range from 1ma to 3a. parameter symbol test conditions min typ max units chip enable en input bias current i en v en = 0v -- 12 -- a rt9018a -- 10 20 vdd shutdown current RT9018B i shdn v en = 0v -- -- 1 a logic-low voltage v enl v dd = 5v -- -- 0.2 en threshold logic-high voltage v enh v dd = 5v 1.2 -- -- v power good pgood rising threshold -- 90 93 % pgood hysteresis 3 10 -- % pgood sink capability i pgood = 10ma -- 0.2 0.4 v pgood delay 0.5 1.5 5 ms thermal protection thermal shutdown temperature t sd -- 160 -- c thermal shutdown hysteresis t sd -- 30 -- c thermal shutdown temperature fold-back v out < 0.4v -- 110 -- c
rt9018a/b 5 ds9018a/b-04 september 2007 www.richtek.com typical operating characteristics load transient response time (2.5ms/div) i out (1a/div) v out (20mv/div) v dd = 5v, v in = 1.8v, v out = 1.2v v in line transient response time (250 s/div) v out (20mv/div) v in v dd = 5v, v out = 1.2v, i out = 0a 3 2 v in line transient response time (250 s/div) v out (20mv/div) v in v dd = 5v, v out = 1.2v, i out = 2a 3 2 load transient response time (2.5ms/div) i out (1a/div) v out (20mv/div) v dd = 5v, v in = 1.8v, v out = 1.2v v dd line transient response time (250 s/div) v out (20mv/div) v dd v in = 1.8v, v out = 1.2v, i out = 2a 5 4 v dd line transient response time (250 s/div) v out (20mv/div) v dd v in = 1.8v, v out = 1.2v, i out = 0a 5 4
rt9018a/b 6 ds9018a/b-04 september 2007 www.richtek.com dropout voltage vs. load current 0 50 100 150 200 250 300 350 400 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 load current (a) dropout voltage (mv) 125 c 25 c -40 c start up from v dd time (500 s/div) pgood (1v/div) v dd (5v/div) i out = 3a v out (1v/div) i in (2a/div) start up from v in time (1ms/div) pgood (1v/div) v in (1v/div) i out = 3a v out (1v/div) i in (2a/div) short circuit protection time (100 s/div) i out (1a/div) v dd = 5v, v in = 1.8v, v out = 1.2v short circuit current vs. temperature 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 -40 -20 0 20 40 60 80 100 temperature short circuit current ishort (a) ( c) start up from enable time (500 s/div) pgood (1v/div) en (1v/div) i out = 3a v out (1v/div) i in (2a/div)
rt9018a/b 7 ds9018a/b-04 september 2007 www.richtek.com v dd standby current vs. temperature -4 0 4 8 12 16 20 24 28 32 -50 -25 0 25 50 75 100 125 temperature (c) v dd standby current (ua) 1 v in = 3.3v, v en = 0v, v dd = 5v quiescent current vs. temperature 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature quiescent current (ua) ( c) v in = 1.8v, v out = 1.2v, i out = 0a quiescent current (ma) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 output voltage vs. temperature 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature output voltage (v) ( c) v in = 1.8v, v adj = 0v, i out = 0a adj threshold voltage vs. temperature 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature adj threshold voltage range (v) ( c) vdd por threshold voltage vs. temperature 2.40 2.45 2.50 2.55 2.60 2.65 2.70 2.75 2.80 2.85 2.90 2.95 3.00 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature por voltage (v) ( c) rising falling reference voltage vs. temperature 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature reference voltage (v) ( c) rt9018a RT9018B
rt9018a/b 8 ds9018a/b-04 september 2007 www.richtek.com over current protection fold back 0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5 3 3.5 4 loading current i out (a) output voltage v out (v) v in = v en = 3.3v, v dd = 5v
rt9018a/b 9 ds9018a/b-04 september 2007 www.richtek.com application information adjustable mode operation the output voltage of rt9018a/b is adjustable from 0.8v to v in by external voltage divider resisters as shown in typical application circuit (figure 2). the value of resisters r1 and r2 should be more than 10k to reduce the power loss. enable the rt9018a/b goes into shutdown mode when the en pin is in the logic low condition. during this condition, the pass transistor, error amplifier, and band gap are turned off, reducing the supply current to 10ua typical. the rt9018a/b goes into operation mode when the en pin is in the logic high condition. if the en pin is floating, note that the rt9018a/b internal initial logic level. for rt9018a, the en pin function pulls high level internally. so the regulator will be turn on when en pin is floating. for RT9018B, the en pin function pulls low level internally. so the regulator will be turn off when en pin is floating. output capacitor the rt9018a/b is specifically designed to employ ceramic output capacitors as low as 10uf. the ceramic capacitors offer significant cost and space savings, along with high frequency noise filtering. input capacitor good bypassing is recommended from input to ground to help improve ac performance. a 10uf input capacitor or greater located as close as possible to the ic is recommended. current limit the rt9018a/b contains an independent current limit and the short circuit current protection to prevent unexpected applications. the current limit monitors and controls the pass transistor ? s gate voltage, limiting the output current to higher than 4.5a typical. when the output voltage is less than 0.4v, the short circuit current protection starts the current fold back function and maintains the loading current 1.8a. the output can be shorted to ground indefinitely without damaging the part. power good the power good function is an open-drain output. connects 100k pull up resistor to vout to obtain an output voltage. the pgood pin will output high immediately after the output voltage arrives 90% of normal output voltage. the pgood pin will output high with typical 1.5ms delay time. thermal-shutdown protection thermal protection limits power dissipation to prevent ic over temperature in rt9018a/b. when the operation junction temperature exceeds 160 c, the over-temperature protection circuit starts the thermal shutdown function and turns the pass transistor off. the pass transistor turn on again after the junction temperature cools by 30 c. rt9018a/b lowers its otp trip level from 160 c to 110 c when output short circuit occurs (v out < 0.4v). it limits ic case temperature under 100 c and provides maximum safety to customer while output short circuit occurring. power dissipation for continuous operation, do not exceed absolute maximum operation junction temperature 125 c. the power dissipation definition in device is: p d = (v in ? v out ) x i out + v in x i q the maximum power dissipation depends on the thermal resistance of ic package, pcb layout, the rate of surroundings airflow and temperature difference between junctions to ambient. the maximum power dissipation can be calculated by following formula: p d(max) = ( t j(max) ? t a ) / ja where t j(max) is the maximum operation junction temperature 125 c, t a is the ambient temperature and the ja is the junction to ambient thermal resistance. for recommended operating conditions specification of rt9018a/b, where t j (max) is the maximum junction temperature of the die (125 c) and t a is the maximum ambient temperature. the junction to ambient thermal resistance for sop-8 (exposed pad) package is 75 c/w on the standard jedec 51-7 (4 layers, 2s2p) thermal test board. the copper thickness is 2oz. the maximum power dissipation at t a = 25 c can be calculated by following formula:
rt9018a/b 10 ds9018a/b-04 september 2007 www.richtek.com p d (max) = (125 c ? 25 c) / (75 c/w) = 1.33w (sop-8 exposed pad on the minimum layout) layout considerations the thermal resistance ja of sop-8 (exposed pad) is determined by the package design and the pcb design. however, the package design had been designed. if possible, it ? s useful to increase thermal performance by the pcb design. the thermal resistance ja can be decreased by adding a copper under the exposed pad of sop-8 (exposed pad) package. as shown in figure 3, the amount of copper area to which the sop-8 (exposed pad) is mounted affects thermal performance. when mounted to the standard sop-8 (exposed pa d) pad (figure 3.a), ja is 75 c/w. adding copper area of pad under the sop-8 (exposed pad) figure 3.b) reduces the ja to 64 c/w. even further, increasing the copper area of pad to 70mm 2 (figure 3.e) reduces the ja to 49 c/w. the maximum power dissipation depends on operating ambient temperature for fixed t j(max) and thermal resistance ja . for rt9018a/b packages, the figure 4 of de-rating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. figure 3 (a). minimum footprint, ja = 75 c/w figure 3 (b). copper area = 10mm 2 , ja = 64 c/w figure 3 (c). copper area = 30mm 2 , ja = 54 c/w figure 4. de-rating curves figure 3. thermal resistance vs. different cooper area layout design figure 3 (d). copper area = 50mm 2 , ja = 51 c/w figure 3 (e). copper area = 70mm 2 , ja = 49 c/w 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 0 20 40 60 80 100 120 140 ambient temperature (c) power dissipation (w) jedec 4-layers pcb 70mm 2 50mm 2 30mm 2 10mm 2 minimum layout copper area
rt9018a/b 11 ds9018a/b-04 september 2007 www.richtek.com 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 symbol dimensions in millimeters dimensions in inches 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 option 1 x 2.000 2.300 0.079 0.091 y 2.000 2.300 0.079 0.091 option 2 x 2.100 2.500 0.083 0.098 y 3.000 3.500 0.118 0.138
rt9018a/b 12 ds9018a/b-04 september 2007 www.richtek.com richtek technology corporation headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 richtek technology corporation taipei office (marketing) 8f, no. 137, lane 235, paochiao road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)89191466 fax: (8862)89191465 email: marketing@richtek.com dimensions in millimeters dimensions in inches symbol min max min max a 0.700 0.800 0.028 0.031 a1 0.000 0.050 0.000 0.002 a3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 d 2.950 3.050 0.116 0.120 d2 2.300 2.650 0.091 0.104 e 2.950 3.050 0.116 0.120 e2 1.500 1.750 0.059 0.069 e 0.500 0.020 l 0.350 0.450 0.014 0.018 w-type 10l dfn 3x3 package 1 1 2 2 note : the configuration of the pin #1 identifier is optional, but must be located within the zone indicated. det ail a pin #1 id and tie bar mark options d 1 e a3 a a1 d2 e2 l b e see detail a

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