View AAT2500IWP-AI-T1_9126931.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

aat2500 1mhz step-down converter/ldo regulator data sheet 1 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 general description the aat2500 is a member of skyworks' total power management ic? (tpmic?) product family. it is a low dropout (ldo) linear regulator and a step-down con- verter with an input voltage range of 2.7v to 5.5v, mak- ing it ideal for applications with single lithium-ion/poly- mer batteries. the ldo has an independent input and is capable of delivering up to 300ma. the linear regulator has been designed for high-speed turn-on and turn-off perfor- mance, fast transient response, and good power supply rejection ratio (psrr). other features include low quies- cent current and a low dropout voltage. the 400ma step-down converter is designed to minimize external component size and cost while maintaining a low 25 a no load quiescent current. peak current mode control with internal compensation provides a stable converter with a low equivalent series resistance (esr) ceramic output capacitor for extremely low output ripple. for maximum battery life, the step-down converter increases to 100% duty cycle and has a typical 180mv dropout voltage at 400ma. the output voltage is either fixed or adjustable with an integrated p- and n-channel mosfet power stage and 1mhz switching frequency. the aat2500 is available in a 12-pin tdfn33 package, and is rated over a temperature range of -40c to +85c. features? v in range: 2.7v to 5.5v ? 300ma ldo current output ? 400mv ldo dropout voltage at 300ma ? high output accuracy: 1.5% ? fast ldo line / load transient response ? 400ma, 96% efficiency step-down converter ? 25 a no load quiescent current for step-down converter ? shutdown current <1 a ? low r ds(on) 0.4 ? integrated power switches ? low dropout 100% duty cycle ? 1mhz switching frequency ? internal soft start ? over-temperature protection ? current limit protection ? available in tdfn33-12 package ? -40c to +85c temperature range applications? cellular phones ? digital cameras ? handheld instruments ? microprocessor/dsp core/io power ? pdas and handheld computers ? portable media players typical application 4.7 h l1 4.7 f c1 2.2 f c4 10 f c3 10nf c5 pgnd 1 lx 2 vp 3 vcc 4 enldo 9 en 10 fb 11 sgnd 12 vldo 5 out 6 gnd 8 byp 7 aat2500 u1 l1 sumida cdrh3d16-4r7 c1 murata grm219r61a475ke19 c3 murata grm21br60j106ke19 v in = 2.7v to 5.5v 3.3v at 300ma 2.5v at 400ma aat2500 step-down converter efficiency load current (ma) efficiency (%) 60 65 70 75 80 85 90 95 100 0.1 1 10 100 1000 v in = 3.3v 1.8v 2.5v downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 2 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 pin descriptions pin # symbol function 1 pgnd step-down converter power ground return pin. connect to the output and input capacitor return. see sec- tion on pcb layout guidelines and evaluation board layout diagram. 2 lx power switching node. output switching node that connects to the output inductor. 3 vp step-down converter power stage supply voltage. must be closely decoupled to pgnd. 4 vcc step-down converter bias supply. connect to vp. 5 vldo ldo input voltage; should be decoupled with 1 f or greater capacitor. 6 out 300ma ldo output pin. a 2.2 f or greater output low-esr ceramic capacitor is required for stability. 7 byp bypass capacitor for the ldo. to improve ac ripple rejection, connect a 10nf capacitor to gnd. this will also provide a soft-start function. 8 gnd ldo ground connection pin. 9 enldo enable pin for ldo. when connected low, ldo is disabled and consumes less than 1 a of current. 10 en step-down converter enable. when connected low, ldo is disabled and consumes less than 1 a. 11 fb step-down converter feedback input pin. for ? xed output voltage versions, this pin is connected to the converter output, forcing the converter to regulate to the speci ? c voltage. for adjustable output versions, an external resistive divider ties to this point and programs the output voltage to the desired value. 12 sgnd step-down converter signal ground. for external feedback, return the feedback resistive divider to this ground. for internal ? xed version, tie to the point of load return. see section on pcb layout guidelines and evaluation board layout diagram. ep exposed paddle (bottom). use properly sized vias for thermal coupling to the ground plane. see section on pcb layout guidelines. pin configuration tdfn33-12 (top view) pgnd lx vp 1 vcc vldo out sgndfb en enldo gnd byp 2 3 4 5 6 12 11 10 9 8 7 downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 3 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at conditions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any one time. 2. mounted on an fr4 board with exposed paddle connected to ground plane. absolute maximum ratings 1 symbol description value units v p , v ldo input voltages to gnd 6.0 v v lx lx to gnd -0.3 to v p + 0.3 v v fb fb to gnd -0.3 to v p + 0.3 v v en en to gnd -0.3 to 6.0 v t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c thermal information symbol description value units p d maximum power dissipation 2 w ? ja thermal resistance 2 50 c/w downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 4 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. the aat2500 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls. 2. to calculate the minimum ldo input voltage, use the following equation: v in(min) = v out(max) + v do(max) , as long as v in 2.5v. 3. for v out <2.1v, v do = 2.5 - v out . 4. v do is defined as v in - v out when v out is 98% of nominal. electrical characteristics 1 v in = v ldo = v out(nom) + 1v for v out options greater than 1.5v. v in = v ldo = 2.5v for v out 1.5v. i out = 1ma, c out = 2.2 f, c in = 1 f, t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units ldo v out output voltage tolerance i out = 1ma to 300ma t a = 25c -1.5 1.5 % t a = -40c to 85c -2.5 2.5 v in input voltage v out + v do 2 5.5 v v do dropout voltage 3, 4 i out = 300ma 400 600 mv ? v out / v out * ? v in line regulation v in = v out + 1v to 5v 0.09 %/v ? v out(line) dynamic line regulation i out = 300ma, v in = v out + 1v to v out + 2v, t r /t f = 2 s 2.5 mv ? v out(load) dynamic load regulation i out = 1ma to 300ma, t r <5 s6 0m v i out output current v out > 1.3v 300 ma i sc short-circuit current v out < 0.4v 600 ma i qldo ldo quiescent current v in = 5v, no load, enldo = v in 70 125 a i shdn shutdown current v in = 5v; enldo = gnd, en = sgnd = pgnd 1.0 a psrr power supply rejection ratio i out = 10ma, c byp = 10nf 1khz 67 db 10khz 47 1mhz 45 t sd over-temperature shutdown threshold 145 c t hys over-temperature shutdown hysteresis 12 c e n output noise e nbw = 300hz to 50khz 50 v rms t c output voltage temperature coef ? cient 22 ppm/c downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 5 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. the aat2500 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls. 2. for adjustable version with higher than 2.5v output, please consult your skyworks representative. electrical characteristics 1 typical values are t a = 25c, v in = v cc = v p = 3.6v. symbol description conditions min typ max units buck converter v in input voltage 2.7 5.5 v v uvlo uvlo threshold v in rising 2.6 v hysteresis 100 mv v in falling 1.8 v v out output voltage tolerance i out = 0 to 400ma, v in = 2.7v to 5.5v -3.0 +3.0 % v out output voltage range fixed output version 0.6 4.0 v adjustable output version 2 0.6 2.5 i qbuck step-down converter quiescent current enldo = gnd, no load, 0.6v adjustable model 25 50 a i shdn shutdown current en = sgnd = pgnd, enldo = gnd 1.0 a i lim p-channel current limit 600 ma r ds(on)h high side switch on resistance 0.45 ? r ds(on)l low side switch on resistance 0.4 ? i lxlk lx leakage current v in = 5.5v, v lx = 0 - v in , en = sgnd = pgnd 1.0 a v linereg line regulation v in = 2.7v to 5.5v 0.2 %/v v fb fb threshold voltage accuracy 0.6v output, no load, t a = 25c 597 600 615 mv i fb fb leakage current 0.6v output 0.2 a r fb fb impedance >0.6v output 250 k ? f osc oscillator frequency t a = 25c 0.7 1.0 1.5 mhz t sd over-temperature shutdown threshold 140 c t hys over-temperature shutdown hysteresis 15 c logic signals v en(l) enable threshold low 0.6 v v en(h) enable threshold high 1.5 v i en(h) leakage current 1.0 1.0 a downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 6 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c. ldo dropout voltage vs. temperature (en = gnd; enldo = v in ) 0 60 120 180 240 300 360 420 480 540 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 temperature ( c) dropout voltage (mv) i l = 300ma i l = 150ma i l = 100ma i l = 50ma ldo dropout characteristics (en = gnd; enldo = v in ) 2.00 2.20 2.40 2.60 2.80 3.00 3.20 2.70 2.80 2.90 3.00 3.10 3.20 3.30 input voltage (v) output voltage (v) i out = 300ma i out = 150ma i out = 100ma i out = 50ma i out = 10ma i out = 0ma ldo dropout voltage vs. output current (en = gnd; enldo = v in ) 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 output current (ma) dropout voltage (mv) 85 c 25 c -40 c ldo ground current vs. input voltage (en = gnd; enldo = v in ) 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 2 2.5 3 3.5 4.5 45 input voltage (v) ground current ( a) i out =0ma i out =10ma i out =50ma i out =150ma i out =300ma ldo output voltage vs. temperature (en = gnd; enldo = v in ) 1.196 1.197 1.198 1.199 1.200 1.201 1.202 1.203 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature ( c) output voltage (v) ldo initial power-up response time (c byp = 10nf; en = gnd; enldo = v in ) time (400s/div) v enldo (5v/div) v out (1v/div) downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 7 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c, v in = v ldo = v cc = v p . ldo turn-off response time (c byp = 10nf; en = gnd; enldo = v in ) time (50s/div) v enldo (5v/div) v out (1v/div) ldo turn-on time from enable (v in present) (c byp = 10nf; en = gnd; enldo = v in ) time (5s/div) v in = 4v v out = 1v/div v enldo = 5v/div ldo line transient response (c byp = 10nf; en = gnd; enldo = v in ) 2.98 2.99 3.00 3.01 3.02 3.03 3.04 time (100s/div) input voltage (v) 0 1 2 3 4 5 6 output voltage (v) v in v out ldo load transient response (c byp = 10nf; en = gnd; enldo = v in ) 2.60 2.65 2.70 2.75 2.80 2.85 2.90 time (100s/div) output voltage (v) -100 0 100 200 300 400 500 output current (ma) v out i out ldo load transient response 300ma (c byp = 10nf; en = gnd; enldo = v in ) 2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 2.90 3.00 time (10s/div) output voltage (v) -100 0 100 200 300 400 500 600 700 800 output current (ma) v out i out ldo self noise (en = gnd; enldo = v in ) 0.001 0.01 0.1 1 10 0.01 0.1 1 10 100 1000 10000 frequency (khz) noise amplitude ( v/rthz) band power:300hz to 50khz = 44.6 vrms 100hz to 100khz = 56.3 vrms downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 8 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c. over-current protection (en = gnd; enldo = v in ) time (50ms/div) output current (ma) -200 0 200 400 600 800 1000 1200 ldo enldo vs. v in 1.050 1.075 1.100 1.125 1.150 1.175 1.200 1.225 1.250 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) v ih v il step-down converter efficiency vs. load (v out = 2.5v; en = v in ; enldo = gnd) output current (ma) efficiency (%) 60 70 80 90 100 0.1 1.0 10 100 1000 v in = 3.3v v in = 3.6v v in = 3.0v step-down converter load regulation (v out = 2.5v; en = v in ; enldo = gnd) output current (ma) output error (%) -2.0 -1.0 0.0 1.0 2.0 0.1 1.0 10 100 1000 v in = 3.0v v in = 3.3v v in = 3.6v step-down converter efficiency vs. load (v out = 1.8v; en = v in ; enldo = gnd) output current (ma) efficiency (%) 50 60 70 80 90 100 0.1 1.0 10 100 1000 v in = 2.7v v in = 3.6v v in = 4.2v step-down converter dc regulation (v out = 1.8v; en = v in ; enldo = gnd) output current (ma) output error (%) -2.0 -1.0 0.0 1.0 2.0 0.1 1.0 10 100 1000 v in = 2.7v v in = 3.6v v in = 4.2v downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 9 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c. step-down converter frequency vs. input voltage (v out = 1.8v; en = v in ; enldo = gnd) input voltage (v) frequency variation (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 step-down converter output voltage error vs. temperature (v in = 3.6v; v o = 1.5v; en = v in ; enldo = gnd) tem p erature ( c ) output error (%) -2.0 -1.0 0.0 1.0 2.0 -40 -20 0 20 40 60 80 100 step-down converter switching frequency vs. temperature (v in = 3.6v; v o = 1.5v; en = v in ; enldo = gnd) temperature ( c) frequency variation (%) -0.20 -0.10 0.00 0.10 0.20 -40 -20 0 20 40 60 80 100 step-down converter input current vs. input voltage (v o = 1.8v; en = v in ; enldo = gnd) input voltage (v) input current ( a) 85 c 25 c -40 c 15 20 25 30 35 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 step-down converter p-channel r ds(on) vs. input voltage (en = v in ; enldo = gnd) input voltage (v) r ds(on) (m ) 300 350 400 450 500 550 600 650 700 750 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 25 c 120 c 100 c 85 c step-down converter n-channel r ds(on) vs. input voltage (en = v in ; enldo = gnd) input voltage (v) r ds(on) (m ) 300 350 400 450 500 550 600 650 700 750 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 25 c 120 c 100 c 85 c downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 10 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c. step-down converter load transient response (30ma - 300ma; v in = 3.6v; v out = 1.8v; c1 = 10 f; en = v in ; enldo = gnd) output voltage (top) (v) load and inductor current (200ma/div) (bottom) time (25 s/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 1.41.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 300ma 30ma step-down converter load transient response (30ma - 300ma; v in = 3.6v; v out = 1.8v; c1 = 10 f; c4 = 100pf; en = v in ; enldo = gnd) output voltage (ac coupled) (top) (v) load and inductor current (200ma/div) (bottom) time (25 s/div) -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.1 0.0 1.2 1.40.8 0.6 1.00.2 0.4-0.2 0.0 300ma 30ma step-down converter load transient response (30ma - 300ma; v in = 3.6v; v out = 1.8v; c1 = 4.7f; en = v in ; enldo = gnd) output voltage (top) (v) load and inductor current (200ma/div) (bottom) time (25s/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 1.41.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 300ma 30ma step-down converter line transient (v out = 1.8v @ 400ma; en = v in ; enldo = gnd) output voltage (top) (v) input voltage (bottom) (v) time (25s/div) 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 step-down converter line regulation (v out = 1.8v; en = v in ; enldo = gnd) input voltage (v) accuracy (%) -0.35 -0.3 -0.25 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 i out = 400ma i out = 100ma i out = 10ma step-down converter soft start (v in = 3.6v; v out = 1.8v; 400ma; en = v in ; enldo = gnd) enable and output voltage (top) (v) inductor current (bottom) (a) time (250s/div) -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 11 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 typical characteristicsunless otherwise noted, v in = 5v, t a = 25c. step-down converter output ripple (v in = 3.6v; v out = 1.8v; 400ma; en = v in ; enldo = gnd) output voltage (ac coupled) (top) (mv) inductor current (bottom) (a) time (250ns/div) -120 -100 -80 -60 -40 -20 0 20 40 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 12 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 functional block diagram en lx erroramp. logic dh dl pgnd vp fb gnd voltage reference voltage reference error amp. out control logic vldo fast start control enldo byp sgnd vcc see note over-current protection note: internal resistor divider included for 1.2v versions. for low voltage versions, the feedback pin is tied directly to the error amplifier input. functional description the aat2500 is a high performance power management ic comprised of a buck converter and a linear regulator. the buck converter is a high efficiency converter capable of delivering up to 400ma. designed to operate at 1.0mhz, the converter requires only three external com- ponents (c in , c out , and l x ) and is stable with a ceramic output capacitor. the linear regulator delivers 300ma and is also stable with ceramic capacitors. linear regulator the advanced circuit design of the linear regulator has been specifically optimized for very fast start-up and shutdown timing. this proprietary cmos ldo has also been tailored for superior transient response character- istics. these traits are particularly important for applica- tions that require fast power supply timing. the high-speed turn-on capability is enabled through implementation of a fast-start control circuit, which accelerates the power-up behavior of fundamental con- trol and feedback circuits within the ldo regulator. fast turn-off time response is achieved by an active output pull-down circuit, which is enabled when the ldo regula- tor is placed in shutdown mode. this active fast shut- down circuit has no adverse effect on normal device operation. the ldo regulator output has been specifi- cally optimized to function with low-cost, low-esr ceramic capacitors; however, the design will allow for operation over a wide range of capacitor types. a bypass pin has been provided to allow the addition of an optional voltage reference bypass capacitor to reduce downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 13 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 output self noise and increase power supply ripple rejec- tion. device self noise and psrr will be improved by the addition of a small ceramic capacitor in this pin. however, increased values of c bypass may slow down the ldo regu- lator turn-on time. the regulator comes with complete short-circuit and thermal protection. the combination of these two internal protection circuits gives a comprehen- sive safety system to guard against extreme adverse operating conditions. the regulator features an enable/disable function. this pin (enldo) is active high and is compatible with cmos logic. to assure the ldo regulator will switch on, the enldo turn-on control level must be greater than 1.5v. the ldo regulator will go into the disable shutdown mode when the voltage on the en pin falls below 0.6v. if the enable function is not needed in a specific applica- tion, it may be tied to v in to keep the ldo regulator in a continuously on state.when the regulator is in shutdown mode, an internal 1.5k ? resistor is connected between out and gnd. this is intended to discharge c out when the ldo regulator is disabled. the internal 1.5k ? resistor has no adverse impact on device turn-on time.step-down converter the aat2500 buck is a constant frequency peak current mode pwm converter with internal compensation. it is designed to operate with an input voltage range of 2.7v to 5.5v. the output voltage ranges from 0.6v to the input voltage for the internally fixed version, and up to 2.5v for the externally adjustable version. the 0.6v fixed model shown in figure 1 is also the adjustable version and is externally programmable with a resistive divider, as shown in figure 2. the converter mosfet power stage is sized for 400ma load capability with up to 96% efficiency. light load efficiency exceeds 80% at a 500 a load. soft start the aat2500 soft-start control prevents output voltage overshoot and limits inrush current when either the input power or the enable input is applied. when pulled low, the enable input forces the converter into a low-power, non- switching state with a bias current of less than 1 a. low dropout operation for conditions where the input voltage drops to the out- put voltage level, the converter duty cycle increases to 100%. as 100% duty cycle is approached, the minimum off-time initially forces the high side on-time to exceed the 1mhz clock cycle and reduce the effective switching frequency. once the input drops below the level where the output can be regulated, the high side p-channel mosfet is turned on continuously for 100% duty cycle. at 100% duty cycle, the output voltage tracks the input voltage minus the ir drop of the high side p-channel mosfet r ds(on) . low supply the under-voltage lockout (uvlo) guarantees sufficient v in bias and proper operation of all internal circuitry prior to activation. fault protection for overload conditions, the peak inductor current is lim- ited. thermal protection disables switching when the internal dissipation or ambient temperature becomes excessive. the junction over-temperature threshold is 140c with 15c of hysteresis. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 14 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 applications informationlinear regulator input and output capacitors an input capacitor is not required for basic operation of the linear regulator. however, if the aat2500 is physically located more than three centimeters from an input power source, a c in capacitor will be needed for stable operation. typically, a 1 f or larger capacitor is recommended for c in in most applications. c in should be located as closely to the device v in pin as practically possible. an input capacitor greater than 1 f will offer superior input line transient response and maximize power supply ripple rejection. ceramic, tantalum, or aluminum elec- trolytic capacitors may be selected for c in . there is no specific capacitor esr requirement for c in . however, for 300ma ldo regulator output operation, ceramic capaci- tors are recommended for c in due to their inherent capa- bility over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. for proper load voltage regulation and operational stabil- ity, a capacitor is required between out and gnd. the c out capacitor connection to the ldo regulator ground pin should be made as directly as practically possible for maximum device performance. since the regulator has been designed to function with very low esr capacitors, ceramic capacitors in the 1.0 f to 10 f range are rec- ommended for best performance. applications utilizing the exceptionally low output noise and optimum power supply ripple rejection should use 2.2 f or greater for c out . in low output current applications, where output load is less than 10ma, the minimum value for c out can be as low as 0.47 f. equivalent series resistance esr is a very important characteristic to consider when selecting a capacitor. esr is the internal series resistance associated with a capacitor that includes lead resistance, internal connections, size and area, material composi- tion, and ambient temperature. typically, capacitor esr is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or alumi- num electrolytic capacitors. bypass capacitor and low noise applications a bypass capacitor pin is provided to enhance the low noise characteristics of the ldo. the bypass capacitor is not necessary for operation; however, for best device performance, a small ceramic capacitor in the range of 470pf to 10nf should be placed between the bypass pin (byp) and the device ground pin (gnd). to practically realize the highest power supply ripple rejection and low- est output noise performance, it is critical that the capac- itor connection between the byp pin and gnd pin be direct and pcb traces should be as short as possible. dc leakage on this pin can affect the ldo regulator out- put noise and voltage regulation performance. for this reason, the use of a low leakage, high quality ceramic (npo or c0g type) or film capacitor is highly recom- mended. l1 4.7 f c1 v outbuck v in 4.7 f c4 10 f c3 10nf c5 v outldo pgnd 1 lx 2 vp 3 vcc 4 enldo 9 en 10 fb 11 sgnd 12 vldo 5 out 6 gnd 8 byp 7 aat2500 u1 l1 4.7 f c1 v in r1 59k r2 4.7 f c4 10 f c3 10nf c5 v outldo v outbuck 100pf c8 pgnd 1 lx 2 vp 3 vcc 4 enldo 9 en 10 fb 11 sgnd 12 vldo 5 out 6 gnd 8 byp 7 aat2500 u1 figure 1: aat2500 fixed output. figure 2: aat2500 with adjustable step-down output and enhanced transient response. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 15 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 step-down converterinductor selection the step-down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. the output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. the internal slope compensation for the adjustable and low-voltage fixed versions of the aat2500 is 0.24a/ s. this equates to a slope compensation that is 75% of the inductor cur- rent down slope for a 1.5v output and 4.7 h inductor. 0.75 v o m = = = 0.24 l 0.75 1.5v 4.7 h a s this is the internal slope compensation for the adjust- able (0.6v) version or low-voltage fixed versions. when externally programming the 0.6v version to 1.5v, the calculated inductance is 7.5 h. 0.75 v o l = = 3 v o = 3 1.5v = 4.5 h m 0.75 v o 0.24a s a s a a s in this case, a standard 4.7 h value is selected. manufacturers specifications list both the inductor dc current rating, which is a thermal limitation, and the peak current rating, which is determined by the satura- tion characteristics. the inductor should not show any appreciable saturation under normal load conditions. some inductors may meet the peak and average current ratings yet result in excessive losses due to a high dcr. always consider the losses associated with the dcr and its effect on the total converter efficiency when selecting an inductor. the 4.7 h cdrh3d16 series inductor selected from sumida has a 105m ? dcr and a 900ma dc current rat- ing. at full load, the inductor dc loss is 17mw which gives a 2.8% loss in efficiency for a 400ma, 1.5v output. input capacitor select a 4.7 f to 10 f x7r or x5r ceramic capacitor for the input. to estimate the required input capacitor size, determine the acceptable input ripple level (v pp ) and solve for c. the calculated value varies with input voltage and is a maximum when v in is double the output voltage. ?? 1 - ?? v obuck v in c in = v obuck v in ?? - esr f s ?? v pp i obuck ?? 1 - = for v in = 2 v obuc k ?? v obuck v in v obuck v in 14 c in(min) = 1 ?? - esr 4 f s ?? v pp i obuck always examine the ceramic capacitor dc voltage coef- ficient characteristics when selecting the proper value. for example, the capacitance of a 10 f, 6.3v, x5r ceramic capacitor with 5.0v dc applied is actually about 6 f. the maximum input capacitor rms current is: ?? i rms = i obuck 1 - ?? v obuck v in v obuck v in the input capacitor rms ripple current varies with the input and output voltage and will always be less than or equal to half of the total dc load current. ?? 1 - = d (1 - d) = 0.5 2 = ?? v obuck v in v obuck v in 12 for v in = 2 x v obuck i obuck rms(max) i 2 = the term ?? 1 - ?? v obuck v in v obuck v in appears in both the input volt- age ripple and input capacitor rms current equations and is a maximum when v obuck is twice v in . this is why the input voltage ripple and the input capacitor rms cur- rent ripple are a maximum at 50% duty cycle. the input capacitor provides a low impedance loop for the edges of pulsed current drawn by the aat2500. low esr/esl x7r and x5r ceramic capacitors are ideal for this function. to minimize stray inductance, the capaci- tor should be placed as closely as possible to the ic. this keeps the high frequency content of the input current localized, minimizing emi and input voltage ripple. the proper placement of the input capacitor (c2) can be seen in the evaluation board layout in figure 3. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 16 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 a laboratory test set-up typically consists of two long wires running from the bench power supply to the evalu- ation board input voltage pins. the inductance of these wires, along with the low-esr ceramic input capacitor, can create a high q network that may affect converter performance. this problem often becomes apparent in the form of excessive ringing in the output voltage dur- ing load transients. errors in the loop phase and gain measurements can also result. since the inductance of a short pcb trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. in applications where the input power source lead induc- tance cannot be reduced to a level that does not affect the converter performance, a high esr tantalum or alu- minum electrolytic should be placed in parallel with the low esr, esl bypass ceramic. this dampens the high q network and stabilizes the system. output capacitor the output capacitor limits the output ripple and pro- vides holdup during large load transitions. a 4.7 f to 10 f x5r or x7r ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the esr and esl charac- teristics necessary for low output ripple. the output voltage droop due to a load transient is dom- inated by the capacitance of the ceramic output capacitor. during a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. the relationship of the output volt- age droop during the three switching cycles to the output capacitance can be estimated by: c out = 3 i load v droop f s once the average inductor current increases to the dc load level, the output voltage recovers. the above equa- tion establishes a limit on the minimum value for the output capacitor with respect to load transients. the internal voltage loop compensation also limits the minimum output capacitor value to 4.7 f. this is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. increased output capac- itance will reduce the crossover frequency with greater phase margin. the maximum output capacitor rms ripple current is given by: 1 23 v out (v in(max) - v out ) rms(max) i l f v in(max) = dissipation due to the rms current in the ceramic output capacitor esr is typically minimal, resulting in less than a few degrees rise in hot-spot temperature. figure 3: aat2500 evaluation board top side. figure 4: aat2500 evaluation board bottom side. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 17 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. for step-down converter, enhanced transient configuration c8 = 100pf and c1 = 10uf. adjustable output resistor selection for applications requiring an adjustable output voltage, the 0.6v version can be externally programmed. resistors r1 and r2 of figure 5 program the output to regulate at a voltage higher than 0.6v. to limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum suggested value for r2 is 59k ? . although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback node, making it more sensitive to external noise and interference. table 1 summarizes the resistor values for various output volt- ages with r2 set to either 59k ? for good noise immu- nity or 221k ? for reduced no load input current. ???? r1 = -1 r2 = - 1 59k = 88.5k v out v ref ???? 1.5v 0.6v the adjustable version of the aat2500, combined with an external feedforward capacitor (c8 in figures 2 and 5), delivers enhanced transient response for extreme pulsed load applications. the addition of the feedforward capacitor typically requires a larger output capacitor c1 for stability. v out (v) r2 = 59k r1 (k ) r2 = 221k r1 (k ) 0.8 19.6 75 0.9 29.4 113 1.0 39.2 150 1.1 49.9 187 1.2 59.0 221 1.3 68.1 261 1.4 78.7 301 1.5 88.7 332 1.8 118 442 1.85 124 464 2.0 137 523 2.5 187 715 table 1: adjustable resistor values for use with 0.6v step-down converter. table 3 l1 4.7 f 1 c1 10 f c2 gnd v in1 1 2 3 buck enable lx1 gnd table 3 r1 59k r2 pgnd 1 lx 2 vp 3 vcc 4 enldo 9 en 10 fb 11 sgnd 12 in 5 out 6 gnd 8 byp 7 aat2500 u1 4.7 f c4 10 f c3 10nf c5 1 2 3 ldo enable v outldo v outbuck 1 2 3 ldo input 0.01 f c7 c8 1 n/a c9 figure 5: aat2500 evaluation board schematic. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 18 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 thermal calculationsthere are three types of losses associated with the aat2500 step-down converter: switching losses, con- duction losses, and quiescent current losses. conduction losses are associated with the r ds(on) characteristics of the power output switching devices. switching losses are dominated by the gate charge of the power output switching devices. at full load, assuming continuous con- duction mode (ccm), a simplified form of the step-down converter and ldo losses is given by: p total i obuck 2 (r dson(hs) v obuck + r dson(ls) [v in - v obuck ]) v in = + (t sw f i obuck + i qbuck + i qldo ) v in + i oldo (v in - v oldo ) i qbuck is the step-down converter quiescent current and i qldo is the ldo quiescent current. the term t sw is used to estimate the full load step-down converter switching losses. for the condition where the buck converter is in dropout at 100% duty cycle, the total device dissipation reduces to: p total = i obuck 2 r dson(hs) + i oldo (v in - v oldo ) + (i qbuck + i qldo ) v in since r ds(on) , quiescent current, and switching losses all vary with input voltage, the total losses should be inves- tigated over the complete input voltage range. given the total losses, the maximum junction tempera- ture can be derived from the ? ja for the tdfn33-12 pack- age which is 50c/w. t j(max) = p total ja + t amb pcb layout the following guidelines should be used to ensure a proper layout. 1. the input capacitor c2 should connect as closely as possible to vp and pgnd, as shown in figure 4. 2. the output capacitor and inductor should be con- nected as closely as possible. the connection of the inductor to the lx pin should also be as short as pos- sible. 3. the feedback trace should be separate from any power trace and connect as closely as possible to the load point. sensing along a high-current load trace will degrade dc load regulation. if external feedback resistors are used, they should be placed as closely as possible to the fb pin. this prevents noise from being coupled into the high impedance feedback node. 4. the resistance of the trace from the load return to gnd should be kept to a minimum. this will help to minimize any error in dc regulation due to differ- ences in the potential of the internal signal ground and the power ground. 5. for good thermal coupling, pcb vias are required from the pad for the tdfn paddle to the ground plane. the via diameter should be 0.3mm to 0.33mm and positioned on a 1.2mm grid. 6. the ldo bypass capacitor (c5) should be connected directly between pins 7 (byp) and 8 (gnd). downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 19 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 step-down converter design examplespecifications v obuck = 1.8v @ 400ma (adjustable using 0.6v version), pulsed load ? i load = 300ma v oldo = 3.3v @ 300ma v in = 2.7v to 4.2v (3.6v nominal) f s = 1.0mhz t amb = 85c 1.8v buck output inductor l1 = 3 v o2 = 3 1.8v = 5.4 h s a s a (see table 1) for sumida inductor cdrh3d16, 4.7 h, dcr = 105m ? . v obuck v obuck 1.8 v 1.8v i l1 = ? 1 - = ? 1 - = 218ma l1 ? f v in 4.7 h ? 1.0mhz 4.2v i pkl1 = i obuck + i l1 = 0.4a + 0.11a = 0.51a 2 p l1 = i obuck 2 ? dcr = 0.4a 2 ? 105m = 17mw ?? ?? ?? ?? 1.8v output capacitorv droop = 0.2v 1 23 1 1.8v (4.2v - 1.8v) 4.7 h 1.0mhz 4.2v 23 rms i l1 f v in(max) = 3 i load v droop f s 3 0.3a 0.2v 1mhz c out = = = 4.5 f = 63marms (v obuck ) (v in(max) - v obuck ) = p esr = esr i rms 2 = 5m (63ma) 2 = 20 w input capacitorinput ripple v pp = 25mv c in = = = 4.75 f 1 ?? - esr 4 f s ?? v pp i obuck 1 ?? - 5m 4 1mhz ?? 25mv 0.4a i obuck rms ip = esr i rms 2 = 5m ( 0.2a ) 2 = 0.2mw 2 = = 0.2arms downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 20 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 aat2500 losses p total + (t sw f i obuck + i qbuck + i qldo ) v in + (v in - v ldo ) i ldo i obuck 2 (r dson(hs) v obuck + r dson(ls) [v in - v obuck ] ) v in = = + (5ns 1.0mhz 0.4a + 50 a +125 a) 4.2v + (4.2v - 3.3v) 0.3a = 392mw 0.4 2 (0.725 1.8v + 0.7 [4.2v - 1.8v]) 4.2v t j(max) = t amb + ja p loss = 85 c + (50 c/w) 392mw = 105 c downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 21 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. for reduced quiescent current r2 = 221k ? . v out (v) adjustable version (0.6v device) r1 (k ) r2 = 59k r1 (k ) r2 = 221k 1 l1 ( h) 0.8 19.6 75.0 4.7 0.9 29.4 113 4.7 1.0 39.2 150 4.7 1.1 49.9 187 4.7 1.2 59.0 221 4.7 1.3 68.1 261 4.7 1.4 78.7 301 4.7 1.5 88.7 332 4.7 1.8 118 442 4.7 1.85 124 464 4.7 2.0 137 523 4.7 or 6.8 2.5 187 715 10 v out (v) fixed version r1 (k ) r2 not used l1 ( h) 0.6-3.3v 0 4.7 table 3: evaluation board component values. manufacturer part number inductance ( h) max dc current (a) dcr ( ) size (mm) lxwxh type sumida cdrh3d16-4r7 4.7 0.90 0.11 3.8x3.8x1.8 shielded sumida cdrh3d16-100 10 0.55 0.21 3.8x3.8x1.8 shielded murata lqh32cn4r7m23 4.7 0.45 0.20 2.5x3.2x2.0 non-shielded murata lqh32cn4r7m33 4.7 0.65 0.15 2.5x3.2x2.0 non-shielded murata lqh32cn4r7m53 4.7 0.65 0.15 2.5x3.2x1.55 non-shielded coilcraft lpo6610-472 4.7 1.10 0.20 5.5x6.6x1.0 1mm coilcraft lpo3310-472 4.7 0.80 0.27 3.3x3.3x1.0 1mm coiltronics sdrc10-4r7 4.7 1.53 0.117 4.5x3.6x1.0 1mm shielded coiltronics sdr10-4r7 4.7 1.30 0.122 5.7x4.4x1.0 1mm shielded coiltronics sd3118-4r7 4.7 0.98 0.122 3.1x3.1x1.85 shielded coiltronics sd18-4r7 4.7 1.77 0.082 5.2x5.2x1.8 shielded table 4: typical surface mount inductors. manufacturer part number value voltage temp. co. case murata grm21br61a475ka73l 4.7 f 10v x5r 0805 murata grm18br60j475ke19d 4.7 f 6.3v x5r 0603 murata grm21br60j106ke19 10 f 6.3v x5r 0805 murata grm21br60j226me39 22 f 6.3v x5r 0805 table 5: surface mount capacitors. downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 22 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . 3. contact sales for availability. 4. product not available for u.s. market. ordering information package voltage marking 1 part number (tape and reel) 2 buck converter ldo tdfn33-12 adj - 0.6v 3.3v nzxyy aat2500iwp-aw-t1 4 tdfn33-12 adj - 0.6v 3.0v nyxyy aat2500iwp-at-t1 4 tdfn33-12 adj - 0.6v 2.8v oaxyy aat2500iwp-aq-t1 4 tdfn33-12 adj - 0.6v 1.8v onxyy AAT2500IWP-AI-T1 4 tdfn33-12 1.8v 3.3v shxyy aat2500iwp-iw t1 4 skyworks green? products are compliant with all applicable legislation and are halogen-free. for additional information, refer to skyworks de?ition of green , document number sq04-0074. legend voltage code adjustable (0.6v) a 0.9 b 1.2 e 1.5 g 1.8 i 1.9 y 2.5 n 2.6 o 2.7 p 2.8 q 2.85 r 2.9 s3.0 t 3.3 w 4.2 c downloaded from: http:///
aat2500 1mhz step-down converter/ldo regulator data sheet 23 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202014a skyworks proprietary information products and product information are subject to change without notice. june 4, 2012 copyright ? 2012 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyworks solutions, inc. (skyworks) products or services. these materials, including the information contained herein, are provided by sky works as a service to its customers and may be used for informational purposes only by the customer. skyworks assumes no responsibility fo r errors or omissions in these materials or the information contained herein. sky- works may change its documentation, products, services, speci ? cations or product descriptions at any time, without notice. skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for con ? icts, incompatibilities, or other dif ? culties arising from any future changes. no license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. skyworks assumes no liability for any materials, products or informatio n provided here- under, including the sale, distribution, reproduction or use of skyworks products, information or materials, except as may be provided in skyworks terms and conditions of sale. the materials, products and information are provided as is without warranty of any kind, whether express, implied, statutory, or otherwise, including fitness for a particular purpose or use, merchantability, performance, quality or non-infringement of any intellectual property right; all such warranti es are hereby expressly disclaimed. skyworks does not warrant the accuracy or completeness of the information, text, graphics or other items contained within these materials. skyworks shall not be liable for any damages, in- cluding but not limited to any special, indirect, incidental, statutory, or consequential damages, including without limitation, lost revenues or lost profits that may result from the use of the materials or information, whether or not the recipient of materials has been advised of the possibility of such damage. skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the skyworks products could lead to personal injury, death, physical or en- vironmental damage. skyworks customers using or selling skyworks products for use in such applications do so at their own risk and agree to fully indemnify skyworks for any damages resulting from such improper use or sale. customers are responsible for their products and applications using skyworks products, which may deviate from published speci ? cations as a result of design defects, errors, or operation of products outside of pub- lished parameters or design speci ? cations. customers should include design and operating safeguards to minimize these and other risks. skyworks assumes no liabi lity for applications assistance, customer product design, or damage to any equipment resulting from the use of skyworks products outside of stated published speci ? cations or parameters. skyworks, the skyworks symbol, and breakthrough simplicity are trademarks or registered trademarks of skyworks solutions, inc., in the united states and other countries. third-party brands and names are for identi ? cation purposes only, and are the property of their respective owners. additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 1. the leadless package family, which includes qfn, tqfn, dfn, tdfn and stdfn, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. a solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder c onnection. package information 1 tdfn33-12 top view bottom view detail "a" side view 3.00 0.05 index area detail "a" 1.70 0.05 3.00 0.05 0.05 0.05 0.23 0.05 0.75 0.05 2.40 0.05 pin 1 indicator (optional) 0.40 0.05 0.45 0.05 0.23 0.05 0.1 ref c0.3 all dimensions in millimeters. downloaded from: http:///

▲Up To Search▲

Price & Availability of AAT2500IWP-AI-T1

	To Download AAT2500IWP-AI-T1 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .