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1 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 general description the AAT2113B switchreg? is a 1.5a step-down con- verter with a typical input voltage of 3.3v and a fixed output voltage of 1.2v or an adjustable output. the 3.3mhz switching frequency enables the use of small external components. the ultra-small 2mm x 2mm foot- print and high efficiency make the AAT2113B an ideal choice for portable applications. the AAT2113B delivers 1.5a maximum output current while consuming only 55 a no-load quiescent current. low r ds(on) integrated mosfets and 100% duty cycle operation make the AAT2113B the ideal choice for high output voltage, high current applications which require a low dropout threshold. the AAT2113B provides excellent transient response and output accuracy across the operating range. no external compensation is required. the AAT2113B maintains high efficiency throughout the load range. the unique low-noise architecture reduces ripple and spectral noise. the AAT2113B automatically optimizes efficiency during light load mode (ll) and maintains constant frequency and low output ripple dur- ing pwm mode. over-temperature and short circuit protection safeguard the AAT2113B and system components from damage. the AAT2113B is available in a pb-free, ultra-small, low profile, 8-pin 2mm x 2mm ftdfn package. the product is rated over a temperature range of -40c to 85c. features ? 5mm x 5mm total solution size ? 1.5a maximum output current ? tiny 0.47 h chip inductor ? excellent transient response ? input voltage: 2.7v to 5.5v ? ultra-small, low profile 8-pin 2mm x 2mm ftdfn package ? fixed or adjustable output voltage options: ? fixed output voltage: 1.2v ? adjustable output voltage: 1.0v to 2.5v ? high efficiency, low noise architecture ? 3.3mhz switching frequency ? no external compensation required ? 55 a no load quiescent current ? 100% duty cycle low-dropout operation ? internal soft start ? over-temperature and current limit protection ? <1 a shutdown current ? -40c to 85c temperature range applications ? cellular phones ? digital cameras ? hard disk drives ? mp3 players ? pdas and handheld computers ? portable media players ? usb devices ? wireless network cards typical application load transient response (v in = 5v; v out = 1.2v; i out = 10% to 100%; c out = 10f, 6.3v, 0603 ) time (20s/div) 150ma 1.1v 1.15v 1.2v 1.25v 1.3v 1.5a 100mv 1.2v/1.5a 0.47h l1 2. 7v to 5.5v c1 4.7f 6.3v 0603 c3 1.0f 6.3v 0402 c3 10f 6.3v 0603 vin vout en fb lx pgnd vcc vp lx agnd ftdfn 22-8 u1 AAT2113B
2 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 pin descriptions pin # symbol function 1 pgnd main power ground return pin. connect to the output and input capacitor return. 2 vp input power supply tied to the source of the high side p-channel mosfet. 3 vcc power supply; supplies power for the internal circuitry. 4fb feedback input pin. this pin is connected directly to the converter output for the 1.2v xed output version, or connected to an external resistor divider for the adjustable output version. 5 agnd analog ground. this pin is internally connected to the analog ground of the control circuitry. 6en enable pin. a logic low disables the converter and it consumes less than 1 a of current. when connected high, it resumes normal operation. 7, 8 lx switching node. connect the inductor to this pin. it is internally connected to the drain of both high and low side mosfets. pin configuration ftdfn22-8 (top view) vcc fb pgnd vp en agnd lx lx 3 4 1 2 6 5 8 7
3 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 absolute maximum ratings 1 t a = 25c unless otherwise noted. symbol description value units v cc , v p vp, vcc 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 en en to gnd -0.3 to v cc + 0.3 v t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec.) 300 c thermal characteristics symbol description value units ja maximum thermal resistance 70 c/w p d maximum power dissipation 2, 3 1.4 w 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at co nditions 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. 3. derate 14mw/c above 25c.
4 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 electrical characteristics 1 v in = 3.3v, t a = -40c to 85c unless otherwise noted. typical values are at t a = 25c. symbol description conditions min typ max units v in input voltage 2.7 3.3 5.5 v v out output voltage range 1 1.2 2.5 v v uvlo uvlo threshold v in rising 2.4 v hysteresis 180 mv v in falling 1.6 v v out output voltage tolerance i out = 0a to 1.5a, v in = 3.3v, v out = 1.2v xed -3.0 +3.0 % i q quiescent current no load 55 90 a i shdn shutdown current en = gnd 1.0 a i lim current limit 23 a r ds(on)h high side switch on-resistance 140 m r ds(on)l low side switch on-resistance 100 m ? v loadreg load regulation i load = 0a to 1.5a 0.5 % ? v linereg / ? v in line regulation v in = 3.3v to 4.0v 0.3 %/v v fb feedback threshold voltage accuracy (adjustable version) no load, t a = 25c 0.591 0.60 0.609 v i lxleak,r lx reverse leakage current v in unconnected, v lx = 5.5v, en = gnd 1.0 a i fbleak fb leakage current v out = 1.2v 0.2 a f osc internal oscillator frequency 2.6 3.3 3.8 mhz t s start-up time enable to output regulation 60 s t sd over-temperature shutdown threshold 140 c t hys over-temperature shutdown hysteresis 25 c en logic v il en threshold low 0.4 v v ih en threshold high 1.4 v i leak en leakage current v en = 5.5v -1.0 1.0 a 1. the AAT2113B is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is ass ured by design, characterization, and cor- relation with statistical process controls.
5 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics efficiency vs. output current (v out = 1.2v; l = 0.47h ) output current (ma ) efficiency (% ) 0.1 1 10 100 1000 10000 0 10 20 30 40 50 60 70 80 90 100 v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v load regulation (v out = 1.2v; l = 0.47h ) output current (ma ) load regulation (% ) 0.1 1 10 100 1000 10000 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. output current (v out = 1.8v; l = 0.82h ) output current (ma ) efficiency (% ) 0.1 1 10 100 1000 10000 0 10 20 30 40 50 60 70 80 90 100 . v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v load regulation (v out = 1.8v; l = 0.82h ) output current (ma ) load regulation (% ) 0.1 1 10 100 1000 10000 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. output current (v out = 2.5v; l = 1h ) output current (ma ) efficiency (% ) 0.1 1 10 100 1000 10000 0 10 20 30 40 50 60 70 80 90 100 v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v load regulation (v out = 2.5v; l = 1h ) output current (ma ) load regulation (% ) 0.1 1 10 100 1000 10000 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 v in = 5.5v v in = 5.0v v in = 4.2v v in = 3.6v v in = 3.0v
6 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics output voltage error vs. temperature (v out = 1.2v; v in = 3.3v; i out = 1a ) temperature (c) output voltage error (%) -40 -20 0 20 40 60 80 -30 -10 10 30 50 70 90 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 output voltage vs. input voltage (v out = 1.2v; i out = 1a ) input voltage (v) output voltage (v) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 t = 85c t = 25c t = -40c output voltage error vs. temperature (v out = 1.8v; i out = 1a ) temperature (c) output voltage error (%) -40 -20 0 20 40 60 80 -30 -10 10 30 50 70 90 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 output voltage vs. input voltage (v out = 1.8v; i out = 1a ) input voltage (v) output voltage (v) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 1.75 1.76 1.77 1.78 1.79 1.80 1.81 1.82 1.83 1.84 1.85 t = 85c t = 25c t = -40c output voltage error vs. temperature (v out = 2.5v; i out = 1a ) temperature (c) output voltage error (%) -40 -20 0 20 40 60 80 -30 -10 10 30 50 70 90 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 output voltage vs. input voltage (v out = 2.5v; i out = 1a ) input voltage (v) output voltage (v) 3 3.5 4 4.5 5 5.5 2.45 2.46 2.47 2.48 2.49 2.50 2.51 2.52 2.53 2.54 2.55 t = 85c t = 25c t = -40c
7 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics switching frequency vs. temperature (i out = 1a) temperature (c) switching frequency (mhz) -40 -20 -30-100 20406080 10 30 50 70 90 3.14 3.16 3.18 3.20 3.22 3.24 3.26 3.28 3.30 3.32 quiescent current vs. input voltage (no load ) input voltage (v) supply current (a) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 10 20 30 40 50 60 70 80 t = 85c t = 25c t = -40c load transient (v out = 1.2v; v in = 3.3v; i out = 0 to 1.5a; c out = 10f) time (20s/div) output voltage (50mv/div) (top) output current (500ma/div) (bottom) 1.10 1.15 1.20 1.25 1.30 0.0 0.5 1.0 1.5 load transient (v out = 1.2v; v in = 3.3v; i out = 75ma to 1350ma; c out = 10f) time (20s/div) output voltage (50mv/div) (top) output current (500ma/div) (bottom) 1.10 1.15 1.20 1.25 1.30 0.0 0.5 1.0 1.5 load transient (v out = 1.8v; v in = 3.3v; i out = 0 to 1.5a; c out = 10f) time (20s/div) output voltage (50mv/div) (top) output current (500ma/div) (bottom) 1.70 1.75 1.80 1.85 1.90 0.0 0.5 1.0 1.5 load transient (v out = 1.8v; v in = 3.3v; i out = 75ma to 1350ma; c out = 10f) time (20s/div) output voltage (50mv/div) (top) output current (500ma/div) (bottom) 1.70 1.75 1.80 1.85 1.90 0.0 0.5 1.0 1.5
8 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics load transient (v out = 2.5v; v in = 3.6v; i out = 0 to 1.5a; c out = 10f) time (100s/div) output voltage (50mv/div) (top) output current (500ma/div) (bottom) 2.30 2.40 2.50 2.60 2.70 0.0 0.5 1.0 1.5 load transient (v out = 2.5v; v in = 3.6v; i out = 75ma to 1350ma; c out = 10f) time (50s/div) output voltage (100mv/div) (top) output current (500ma/div) (bottom) 2.40 2.50 2.60 2.70 0.0 0.5 1.0 1.5 line transient (v out = 1.2v; v in = 3.3v to 3.6v; i out = 1a) time (50s/div) input voltage (500mv/div) (top) output voltage (5mv/div) (bottom) 3.0 3.5 4.0 1.185 1.190 1.195 1.200 1.205 1.210 line transient (v out = 1.8v; v in = 3.3v to 3.6v; i out = 1a) time (20s/div) input voltage (500mv/div) (top) output voltage (5mv/div) (bottom) 3.0 3.5 4.0 1.790 1.795 1.800 1.805 1.810 1.815 line regulation (v out = 1.2v; l = 0.47h) input voltage (v) line regulation (% ) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 i out = 1500ma i out = 1000ma i out = 500ma i out = 1ma line regulation (v out = 1.8v; l = 0.47h) input voltage (v) line regulation (% ) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 i out = 1500ma i out = 1000ma i out = 500ma i out = 1ma
9 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics line regulation (v out = 2.5v; l = 1h) input voltage (v) line regulation (% ) 3 3.5 4 4.5 5 5.5 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 i out = 1500ma i out = 1000ma i out = 500ma i out = 1ma soft start ( v out = 1.2v; v in = 3.3v; i out = 1a) time (100s/div) enable voltage (top) (1v/div) output voltage (middle) (1v/div) inductor current (bottom) (1a/div) -4 -3 -2 -1 0 1 2 3 4 -1 0 1 2 3 4 5 6 7 soft start ( v out = 1.8v; v in = 3.3v; i out = 1a) time (100s/div) enable voltage (top) (1v/div) output voltage (middle) (1v/div) inductor current (bottom) (1a/div) -4 -3 -2 -1 0 1 2 3 4 -1 0 1 2 3 4 5 6 7 soft start ( v out = 2.5v; v in = 3.3v; i out = 1a) time (100s/div) enable voltage (top) (1v/div) output voltage (middle) (1v/div) inductor current (bottom) (1a/div) -4 -3 -2 -1 0 1 2 3 4 -1 0 1 2 3 4 5 6 7 output voltage ripple ( v out = 1.2v; v in = 3.3v; i out = 1.5a) time (200ns/div) output voltage (top) (20mv/div) inductor current (bottom) (500ma/div) 1.08 1.10 1.12 1.14 1.16 1.18 1.20 1.22 1.24 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 output voltage ripple ( v out = 1.2v; v in = 3.3v; i out = 1ma) time (10s/div) output voltage (top) (10mv/div) inductor current (bottom) (100ma/div) 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6
10 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 typical characteristics output voltage ripple ( v out = 1.8v; v in = 3.3v; i out = 1.5a) time (200ns/div) output voltage (top) (20mv/div) inductor current (bottom) (500ma/div) 1.68 1.70 1.72 1.74 1.76 1.78 1.80 1.82 1.84 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 output voltage ripple ( v out = 1.8v; v in = 3.3v; i out = 1ma) time (10s/div) output voltage (top) (10mv/div) inductor current (bottom) (100ma/div) 1.74 1.75 1.76 1.77 1.78 1.79 1.8 1.81 1.82 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 output voltage ripple ( v out = 1.8v; v in = 3.3v; i out = 1.5a) time (200ns/div) output voltage (top) (20mv/div) inductor current (bottom) (500ma/div) 2.38 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 output voltage ripple ( v out = 2.5v; v in = 3.3v; i out = 1ma) time (50s/div) output voltage (top) (10mv/div) inductor current (bottom) (100ma/div) 2.44 2.45 2.46 2.47 2.48 2.49 2.5 2.51 2.52 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6
11 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 functional description the AAT2113B switchreg is a 1.5a step-down converter with a typical input voltage of 3.3v and a fixed output voltage of 1.2v. the 3.3mhz switching frequency enables the use of small external components. the ultra-small, 2mm x 2mm footprint and high efficiency make the AAT2113B an ideal choice for portable applications. typically, a 0.47 h inductor and a 10 f ceramic capaci- tor are recommended for a 1.2v output (see figure 2 for recommended values). at dropout, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the r ds(on) drop of the p-channel high-side mosfet (plus the dc drop of the external inductor). the device inte- grates extremely low r ds(on) mosfets to achieve low dropout voltage during 100% duty cycle operation. the integrated low-loss mosfet switches can provide excellent efficiency at heavy loads. light load operation maintains high efficiency, low ripple and low spectral noise even at lower currents (typically <150ma). pwm mode operation maintains constant frequency and low output ripple at output loads greater than 200ma. in battery-powered applications, as v in decreases, the converter dynamically adjusts the operating frequency prior to dropout to maintain the required duty cycle and provide accurate output regulation. output regulation is maintained until the dropout voltage, or minimum input voltage, is reached. at 1.5a output load, dropout voltage headroom is approximately 200mv. the AAT2113B typically achieves better than 0.5% output regulation across the input voltage and output load range. a current limit of 3.0a (typical) protects the ic and system components from short-circuit damage. typical no load quiescent current is 55 a. thermal protection completely disables switching when the maximum junction temperature is detected. the junction over-temperature threshold is 140c with 25c of hysteresis. once an over-temperature or over-current fault condition is removed, the output voltage automati- cally recovers. peak current mode control and optimized internal com- pensation provide high loop bandwidth and excellent response to input voltage and fast load transient events. soft start eliminates output voltage overshoot when the enable or the input voltage is applied. under-voltage lockout prevents spurious start-up events. functional block diagram en lx err amp logic dh dl pgnd vp fb agnd v ref = 0.6v input comp vcc AAT2113B-1.2v only
12 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 control loop the AAT2113B is a peak current mode step-down con- verter. the current through the p-channel mosfet (high side) is sensed for current loop control, as well as short- circuit and overload protection. a fixed slope compensa- tion signal is added to the sensed current to maintain stability for duty cycles greater than 50%. the peak current mode loop appears as a voltage-programmed current source in parallel with the output capacitor. the output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. internal loop compensation terminates the transconductance voltage error amplifier output. the reference voltage is internally set to program the con- verter output voltage greater than or equal to 0.6v. soft start/enable soft start limits the current surge seen at the input and eliminates output voltage overshoot. the enable input, when pulled low, forces the AAT2113B into a low-power, non-switching state. the total input current during shut- down is less than 1 a. current limit and over-temperature protection for overload conditions, the peak input current is limit- ed. to minimize power dissipation and stresses under current limit and short-circuit conditions, switching is terminated after entering current limit for a series of pulses. switching is terminated for seven consecutive clock cycles after a current limit has been sensed for a series of four consecutive clock cycles. thermal protection completely disables switching when internal dissipation becomes excessive. the junction over-temperature threshold is 140c with 25c of hys- teresis. once an over-temperature or over-current fault condition is removed, the output voltage automatically recovers. under-voltage lockout internal bias of all circuits is controlled via the vcc input. under-voltage lockout (uvlo) guarantees suffi- cient v in bias and proper operation of all internal cir- cuitry prior to activation. component selection inductor selection the step-down converter uses peak current mode con- trol 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. for applications where the duty cycle is less than 50%, the inductor values can be chosen freely. manufacturer?s 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. for low cost application and a sufficiently small footprint in a 5x5mm area, the lqm2hpnr47mg0 shielded chip inductor, which has 40m dcr and 1.8a dc current rat- ing, is selected for 1.2v output. the inductors listed in table 1 have been used with the AAT2113B. manufacturer part number value ( h) dc resistance ( ) size (mm) murata lqm2hpnr47mg0 0.47 20% 0.04 25% 2.5x2.0x1.0 coilcraft epl2010-421ml 0.42 20% 0.04 25% 2.0x2.0x1.0 epl2010-681ml 0.68 20% 0.058 25% 2.0x2.0x1.0 table 1: AAT2113B list of inductors.
13 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 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 volt- age and is a maximum when v in is double the output voltage. ?? 1 - ?? v o v in c in = v o v in ?? - esr f s ?? v pp i o ?? 1 - = for v in = 2 v o ?? v o v in v o v in 1 4 c in(min) = 1 ?? - esr 4 f s ?? v pp i o 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 3.5v dc applied is actually about 5 f. some examples of dc bias voltage versus capaci- tance for different package sizes are shown in figure 1. dc bias voltage (v) capacitance (f) 0 2 4 6 8 10 12 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0603 package 0805 package figure 1: 10 f capacitor value vs. dc bias voltage for different package sizes. the maximum input capacitor rms current is: i rms = i o 1 - v o v in v o 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 o v in v o v in 1 2 for v in = 2 v o i o rms(max) i 2 = the term ?? 1 - ?? v o v in v o v in appears in both the input voltage ripple and input capacitor rms current equations and is a maximum when v o is twice v in . this is why the input voltage ripple and the input capacitor rms current 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 AAT2113B. low esr/esl x7r and x5r ceramic capacitors are ideal for this function. to minimize stray inductance, the capacitor 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 (c1) can be seen in the evaluation board layout in the layout section of this datasheet (see figure 3). a laboratory test set-up typically consists of two long wires running from the bench power supply to the eval- uation 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 capacitor. this dampens the high q network and stabilizes the system.
14 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 output capacitor the output capacitor limits the output ripple and pre- vents the output voltage droop during large load transi- tions. a 10 f to 22 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 characteristics necessary for low output ripple. the output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. during a step increase in load current, the ceramic out- put 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 voltage 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 10 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. feedback resistor selection resistors r1 and r2 of figure 5 program the output to regulate at a voltage higher than 0.6v for the AAT2113B adjustable version. to limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the suggested value for r2 is 200k . table 1 summarizes the resistor values for vari- ous output voltages with r2 set to either 59k or 200k . alternately, the feedback resistor may be calculated using the following equation: r1 = -1 r2 = - 1 200k = 400k v out v ref 1.8v 0.6v the AAT2113B adjustable version, combined with an external feed forward capacitor (c2 in figure 5), delivers enhanced transient response for extreme pulsed load applications. the suggested value for c2 is in the range of 22pf to 100pf. v out (v) r2 = 59k r1 (k ) r2 = 200k r1 (k ) 1.0 39.2 133 1.1 49.9 165 1.2 59 200 1.3 68.1 232 1.4 78.7 267 1.5 88.7 301 1.6 97.6 332 1.7 107 365 1.8 118 400 2.5 187 634 table 2: feedback resistor selection for adjustable output voltage version. thermal calculations there are three types of losses associated with the AAT2113B 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 losses is given by: p total i o 2 (r ds(on)h v o + r ds(on)l [v in - v o ]) v in = + (t sw f s i o + i q ) v in i q is the step-down converter quiescent current. the term t sw is used to estimate the full load step-down con- verter switching losses. for the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: p total = i o 2 r ds(on)h + (t sw f s i o + i q ) v in
15 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 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 ftdfn22-8 package, which is 70c/w. t j(max) = p total ja + t amb pcb layout considerations the suggested pcb layout for the AAT2113B is shown in figures 3 and 4 (fixed version) or figures 6 and 7 (adjust- able version). the following guidelines should be used to help ensure a proper layout: 1. the input capacitor (c1) should be connected as close as possible to vp and pgnd. 2. the output capacitor and l1 should be connected as closely as possible. the connection of l1 to the lx pin should be as short as possible. 3. for the fixed output version, the feedback trace or fb pin should be separated from any power trace and connected as closely as possible to the load point. sensing along a high-current load trace will degrade dc load regulation. for the adjustable ver- sion, the trace connecting the fb pin to resistors r1 and r2 should be as short as possible by placing r1 and r2 immediately next to the AAT2113B. the sense trace connection from r1 to the output volt- age should be separate from any power trace and connect as closely as possible to the load point. the external feed-forward capacitor c2 should be con- nected as close as possible in parallel with r1 for enhanced transient response. 4. the resistance of the trace from the load return to pgnd 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. connect unused signal pins to ground to avoid unwanted noise coupling.
16 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 1.2v/1.5a u1 AAT2113Bixs-1.2v-t1 skyworks, 3.3mhz fast transient, 1.5a step-down converter , ftdfn22-8, 2x2mm c1 grm188r60j475ke19d, murata, cap, mlc, 4.7f/6.3v, 0603 (h max = 0.9mm) l1 lqm2hpnr47mgo, murata, 0.47h, i sat = 1800ma, dcr = 40m, 2.5 x 2 x 0.9 mm, shielded chip inductor c2 grm188r60j106me47d, mura ta, cap, mlc, 10f/6.3v, 0603 (h max = 0.9mm) c3 grm155r60j105ke19d, murata, cap, mlc, 1f/6.3v, 0402 0.47h l1 2.7v to 5.5v en c1 4.7f c3 1f c2 10f vin vout en 2 fb 5 lx 7 pgnd 1 vcc 6 vp 4 lx 8 agnd 3 ftdfn22-8 u1 AAT2113B figure 2: AAT2113B evaluation board schematic for 1.2v fixed output voltage version. figure 3: AAT2113B evaluation board figure 4: AAT2113B evaluation board top side layout for 1.2v fixed bottom side layout for 1.2v fixed output voltage version. output voltage version.
17 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 1.2v/1.5a u1 AAT2113Bixs-0.6-t1 skyworks, 3.3mhz fast transient, 1.5a step-down converter, ftdfn22-8, 2x2mm c1 grm188r60j475ke19d, murata, cap, mlc, 4.7f/6.3v, 0603 (h max = 0.8mm) c2 optional, 22pf, 0201 l1 lqm2hpnr47mgo, murata, 0.47h, i sat =1.8a, dcr = 0.04, 2.5 x 2 x 1mm, shielded chip inductor r1, r2 carbon film resistor, 200k, 1%, 0201 r3 carbon film resistor, 0 c3 grm188r60j106me47d, murata, cap, mlc, 10f/6.3v, 0603 (h max = 0.8mm) c4 grm155r60j105ke19d, murata, cap, mlc, 1f/6.3v, 0402 0.47h l1 2.7vC5.5v en c1 4.7f c4 1f c3 10f c2 22pf r1 200k r2 200k vin vout en 2 fb 5 lx 7 agnd 1 vcc 6 vp 4 lx 8 pgnd 3 u1 AAT2113B figure 5: AAT2113B evaluation board schematic for adjustable output voltage version. figure 6: AAT2113B evaluation board figure 7: AAT2113B evaluation board top side layout for adjustable bottom side layout for adjustable output voltage version. output voltage version.
18 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 1h l1 en c1 4.7f c4 1f c2 22pf c3 10f r2 200k r1 634k r3 499 v in 2.7v C5.5v v out 2.5v/1.5 a en 2 fb 5 lx 7 agnd 1 vcc 6 vp 4 lx 8 pgnd 3 u1 AAT2113B figure 8: AAT2113B application schematic for 2.5v output voltage.
19 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 AAT2113B design example specifications v out = 1.2v @ 1.5a, pulsed load ? i load = 1.5a v in = 3.3v f s = 3.3mhz t amb = 85c in 8-pin 2x2mm dfn low profile package output inductor for murata, 0.47 h lqm2hpnnr47mg0 shielded chip inductor has a 40m dcr. v o v o 1.2 v 1.2v i = 1 - = 1 - = 0.492m a l1 f s v in 0.47h 3.3mhz 3.3v i pk = i out + i = 1.5a + 0.271a = 1.75a 2 p l1 = i out 2 dcr = 1.5a 2 40m = 90mw output capacitor for v droop = 0.12v (10% output voltage) 3 i load v droop f s 3 1.5a 0.12v 3.3mhz c out = = = 11.4f; use 10f for v droop = 0.06v (5% output voltage) 1 23 1 1.2v (3.3v - 1.2v) 0.47h 3.3mhz 3.3v 23 rms(max) i l f s v in(max) = 3 i load v droop f s 3 1.5a 0.06v 3.3mhz c out = = = 22.7f; use 22f = 142ma rms v out (v in(max) - v out ) = p rms = esr i rms 2 = 5m (142ma) 2 = 0.1mw
20 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 input capacitor for input ripple v pp = 30mv c in = = = 5f; use 4.7f 1 - esr 4 f s v pp i o 1 - 5m 4 3.3mhz 30mv 1.5a i out1 rms i p = esr ( i rms ) 2 = 5m (0.75a) 2 = 2.8mw 2 == 0.75a AAT2113B losses all values assume 85c ambient temperature and thermal resistance of 70c/w in the 8-pin 2x2mm dfn low profile package. p total = i out 2 r ds(on)h + (t sw f sw i out + i q ) v in = 423mw = 1.5a 2 152m + (5ns 3.3mhz 1.5a + 50a) 3.3v t j(max) = t amb + ja p loss = 85 c + (70 c/w) 423mw = 115 c
21 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 2012 ordering information output voltage package marking 1 part number (tape and reel) 2 1.2v ftdfn22-8 AAT2113Bixs-1.2-t1 adjustable (0.6v) ftdfn22-8 k9xyy AAT2113Bixs-0.6-t1 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. package information ftdfn22-8 3 2.000 + 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . 3. 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.
22 AAT2113B 3.3mhz, fast transient 1.5a step-down converter in an 2mm x 2mm package data sheet skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202003a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 24, 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 m aterials, including the information contained herein, are provided by skyworks 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 informati on 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 information provided here- under, including the sale, distribution, reproduction or use of skyworks products, information or materials, except as may be p rovided 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. sk yworks 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 co nditions, posted at www.skyworksinc.com, are incorporated by reference.

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