View AAT1151IKS-10-T1_2482953.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

switchreg ? aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 1 general description the aat1151 switchreg? is a member of analogictech's total power management ic? (tpmic?) product family. the step-down switching converter is ideal for applications where high effi- ciency is required over the full range of output load conditions. the 2.7v to 5.5v input voltage range makes the aat1151 ideal for single-cell lithium- ion/polymer battery applications. capable of more than 700ma with internal mosfets, the current- mode controlled ic provides high efficiency using synchronous rectification. fully integrated compen- sation simplifies system design and lowers external parts count. the device operates at a fixed 850khz switching fre- quency and enters pfm mode for light load current to maintain high efficiency across all load conditions. the aat1151 is available in msop-8 and qfn33-16 packages and is rated over the -40c to +85c tem- perature range. features ?v in range: 2.7v to 5.5v ? up to 95% efficiency ? high initial accuracy 1% ? 110m ? r ds(on) internal switches ? <1a shutdown current ? 850khz switching frequency ? fixed v out or adjustable v out 1.0v ? integrated power switches ? synchronous rectification ? current mode operation ? internal compensation ? stable with ceramic capacitors ? pwm and pfm for optimum efficiency for all load conditions ? internal soft start ? over-temperature protection ? current limit protection ? msop-8 and qfn33-16 packages ? -40c to +85c temperature range applications ? cellular phones ? digital cameras ? mp3 players ? notebook computers ? pdas ? usb-powered equipment ? wireless notebook adapters typical application output 3.0 h 2x 22 f 10 f 0.1 f 100 ? lx vp input fb sgnd aat1151 enable vcc pgnd
aat1151 850khz 700ma synchronous buck dc/dc converter 2 1151.2005.11.1.4 pin descriptions pin configuration msop-8 qfn33-16 (top view) (top view) vp vp vp nc p gnd p gnd p gnd 1 2 3 4 sgnd sgnd en 16 15 14 13 5 6 7 8 12 11 10 9 nc vcc lx lx lx fb 1 2 lx pgnd lx vp fb sgnd en vcc 1 2 3 4 8 7 6 5 pin # msop-8 qfn33-16 symbol function 1 4 fb feedback input pin. this pin is connected to the converter output. it is used to set the output of the converter to regulate to the desired value via an internal resistive divider. for an adjustable output, an external resistive divider is connected to this pin on the 1v model. 2 5, 6 sgnd signal ground. connect the return of all small signal components to this pin. (see board layout rules.) 3 7 en enable input pin. a logic high enables the converter; a logic low forces the aat1151 into shutdown mode reducing the supply current to less than 1a. the pin should not be left floating. 4 9 vcc bias supply. supplies power for the internal circuitry. connect to input power via low pass filter with decoupling to sgnd. 5 10, 11, 12 vp input supply voltage for the converter power stage. must be closely decoupled to pgnd. 6, 7 13, 14, 15 lx connect inductor to these pins. switching node internally connected to the drain of both high- and low-side mosfets. 8 1, 2, 3 pgnd main power ground return pin. connect to the output and input capacitor return. (see board layout rules.) 8, 16 nc not internally connected. ep exposed paddle (bottom); connect to pgnd directly beneath package.
aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 3 absolute maximum ratings 1 thermal characteristics 3 recommended operating conditions symbol description value units t ambient temperature range -40 to 85 c symbol description value units ja thermal resistance (msop-8) 150 c/w p d maximum power dissipation (msop-8) (t a = 25c) 4 667 mw ja thermal resistance (qfn33-16) 50 c/w p d maximum power dissipation (qfn33-16) (t a = 25c) 5 2.0 w symbol description value units v cc , v p v cc , v p to gnd 6 v v lx lx to gnd -0.3 to v p +0.3 v v fb fb to gnd -0.3 to v cc +0.3 v v en en to gnd -0.3 to 6 v t j operating junction temperature range -40 to 150 c v esd esd rating 2 - hbm 3000 v 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at c ondi- tions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any one time. 2. human body model is a 100pf capacitor discharged through a 1.5k ? resistor into each pin. 3. mounted on a demo board. 4. derate 6.7mw/c above 25c. 5. derate 20mw/c above 25c.
aat1151 850khz 700ma synchronous buck dc/dc converter 4 1151.2005.11.1.4 electrical characteristics 1 v in = v cc = v p = 5v, 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 range 2.7 5.5 v v out output voltage tolerance v in = v out + 0.2 to 5.5v, -3.0 +3.0 % i out = 0 to 700ma v uvlo under-voltage lockout v in rising 2.5 v v in falling 1.2 v uvlo(hys) under-voltage lockout hysteresis 250 mv i il input low current v in = v fb = 5.5v 1.0 a i ih input high current v in = v fb = 0 v 1.0 a i q quiescent supply current no load, v fb = 0 v, v in = 4.2v 210 300 a t a = 25c i shdn shutdown current v en = 0 v, v in = 5.5v 1.0 a i lim current limit t a = 25c 1.2 a r ds(on)h high side switch on resistance t a = 25c 110 150 m ? r ds(on)l low side switch on resistance t a = 25c 100 150 m ? efficiency i out = 300ma, v in = 3.5v 92 % ? v out (v out * ? v in ) load regulation v in = 4.2v, i load = 0 to 700ma 0.9 % ? v out /v out line regulation v in = 2.7v to 5.5v 0.1 %/v f osc oscillator frequency t a = 25c 600 850 1200 khz v en(l) enable threshold low 0.6 v v en(h) enable threshold high 1.4 v t sd over-temperature shutdown 140 c threshold t hys over-temperature shutdown 15 c hysteresis 1. the aat1151 is guaranteed to meet performance specifications over the -40c to +85c operating range and is assured by desig n, characterization, and correlation with statistical process controls.
typical characteristics aat1151 efficiency (v out = 2.5v; l = 4.2 h) output current (ma) efficiency (%) 50 55 60 65 70 75 80 85 90 95 100 1 10 100 1000 10000 switching frequency vs. temperature 0 200 400 600 800 1000 1200 -40 -20 0 20 40 60 80 100 temperature ( c) frequency (khz) load and line regulation load current (ma) v out error (%) -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 1 10 100 1000 v in = 3.6v v in = 4.2v v in = 2.7v output voltage vs. temperature 1.78 1.782 1.784 1.786 1.788 1.79 1.792 1.794 -40 -20 0 20 40 60 80 100 temperature ( c) output voltage (v) frequency vs. input voltage 850 860 870 880 890 2.5 3 3.5 4 4.5 5 5.5 input voltage (v) frequency (khz) no load supply current vs. input voltage 2.5 3 3.5 4 4.5 5 5.5 input voltage (v) supply current ( a) 0 50 100 150 200 250 300 t = 85 c t = -40 c t = 25 c aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 5
typical characteristics soft start 1.8v, 0.7a, v in = 3.6v circuit of figure 1 time (200 s/div) enable (top) output (middle) (v) inductor current (bottom) (a) -4 -3 -2 -1 0 1 2 3 4 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 load transient response 50ma to 0.7a v in = 3.6v ? ? circuit of figure 1 time (200 s/div) output voltage (top) (mv) (ac coupled) inductor current (bottom) (a) -120 -100 -80 -60 -40 -20 0 20 40 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 line transient response 1.8v, 0.7a circuit of figure 1 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 time (20 s/div) input voltage (top) (v) -40 -20 0 20 40 60 80 100 120 output voltage (bottom) (mv) output ripple 1.8v, 0.7a, v in = 3.6v circuit of figure 1 time (2 s/div) output voltage (ac coupled) (top) (mv) inductor current (bottom) (a) -60 -50 -40 -30 -20 -10 0 10 20 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 line transient response 1.8v, 50ma circuit of figure 1 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 time (20 s/div) input voltage (top) (v) -40 -20 0 20 40 60 80 100 120 output voltage (bottom) (mv) output ripple 1.8v, 50ma, v in = 3.6v circuit of figure 1 time (2 s/div) output voltage (ac coupled) (top) (mv) inductor current (bottom) (a) -60 -50 -40 -30 -20 -10 0 10 20 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 aat1151 850khz 700ma synchronous buck dc/dc converter 6 1151.2005.11.1.4
typical characteristics output ripple circuit of figure 1 0 5 10 15 20 1 10 100 1000 output current (ma) ripple (mv) v in = 2.7v v in = 3.6v v in = 4.2v aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 7
aat1151 850khz 700ma synchronous buck dc/dc converter 8 1151.2005.11.1.4 functional block diagram v p = 2.7v- 5.5v vcc en sgnd pgnd logic 1.0v ref temp. sensing osc op. amp lx fb dh dl cmp 1m ? operation control loop the aat1151 is a peak current mode buck con- verter. the inner, wide bandwidth loop controls the peak current of the output inductor. the output inductor current is sensed through the p-channel mosfet (high side) and is also used for short-cir- cuit and overload protection. a fixed slope com- pensation signal is added to the sensed current to maintain stability. the loop appears as a voltage programmed current source in parallel with the out- put capacitor. the voltage error amplifier output programs the cur- rent loop for the necessary inductor current to force a constant output voltage for all load and line condi- tions. the voltage feedback resistive divider is inter- nal, dividing the output voltage to the error amplifier reference voltage of 1.0v. the voltage error amplifi- er does not have the large dc gain typical of most error amplifiers. this eliminates the need for exter- nal compensation components, while still providing sufficient dc loop gain for load regulation. the volt- age loop crossover frequency and phase margin are set by the output capacitor value only. pfm/pwm operation light load efficiency is maintained by way of pulse frequency modulation (pfm) control. the aat1151 pfm control forces the peak inductor current to a minimum level regardless of load demand. at medi- um to high load demand, this has no effect on circuit operation and normal pwm controls take over. pfm reduces the switching frequency at light loads, thus reducing the associated switching losses. soft start/enable soft start increases the inductor current limit point in discrete steps when the input voltage or enable input is applied. it limits the current surge seen at the input and eliminates output voltage overshoot. when pulled low, the enable input forces the aat1151 into a low-power, non-switching state. the total input current during shutdown is less than 1a. power and signal source separate small signal ground and power supply pins isolate the internal control circuitry from the noise associated with the output mosfet switching. the low pass filter r1 and c2 in schematic figure 1 fil- ters the noise associated with the power switching.
aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 9 current limit and over-temperature protection for overload conditions, the peak input current is limited. as load impedance decreases and the output voltage falls closer to zero, more power is dissipated internally, raising the device tempera- ture. thermal protection completely disables switching when internal dissipation becomes excessive, protecting the device from damage. the junction over-temperature threshold is 140c with 10c of hysteresis. inductor the output inductor is selected to limit the ripple cur- rent to some predetermined value, typically 20% to 40% of the full load current at the maximum input voltage. manufacturer's specifications list both the inductor dc current rating, which is a thermal limita- tion, and the peak current rating, which is deter- mined by the saturation characteristics. the inductor should not show any appreciable saturation under normal load conditions. during overload and tran- sient conditions, the average current in the inductor can meet or exceed the current limit point of the aat1151. these conditions can tolerate greater sat- uration in the inductor without degradation in con- verter performance. some inductors may meet the peak and average current ratings yet result in exces- sive 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 a 1.0 amp load and the ripple set to 40% at the maximum input voltage, the maximum peak-to- peak ripple current is 280ma. the inductance value required is 2.84h. the factor "k" is the fraction of full load selected for the ripple current at the maximum input voltage. for ripple current at 40% of the full load current, the peak current will be 120% of full load. selecting a standard value of 3.0h gives 38% ripple current. a 3.0h inductor selected from the sumida cdrh5d28 series has a 24m ? dcr and a 2.4a dc current rating. at full load, the inductor dc loss is 24mw, which amounts to a 1.6% loss in efficiency. l = 1 - v out v out i o k f v in = 1 - 1.5v 1.5v 1a 0.4 850khz 4.2v ?? ?? ?? ? ? ?? ? ? = 2.84 h figure 1: aat1151 evaluation board. efficiency vs. load current (v out = 1.8v) 50 60 70 80 90 100 1 10 100 1000 load current (ma) efficiency (%) 2.7v 3.6v 4.2v l1 3.3 h c3, c4 2x22 f c1 10 f r1 100 c2 0.1 f c1 murata 10 f 6.3v x5r grm42-6x5r106k6.3 r2 100k c3-c4 murata 22 f 6.3v grm21br60j226me39l x5r 0805 1.8 v 2.7v-4.2v out 4 gnd 5 en 7 vcc 9 vp 10 lx 13 lx 14 pgnd 3 vp 11 gnd 6 pgnd 2 lx 15 n/c 16 pgnd 1 n/c 8 vp 12 u1 aat1151-qfn r6 100k l1 sumida cdrh3d16-4r7nc or cdrh3d16-3r3nc
aat1151 850khz 700ma synchronous buck dc/dc converter 10 1151.2005.11.1.4 input capacitor the primary function of the input capacitor is to pro- vide a low impedance loop for the edges of pulsed current drawn by the aat1151. a low esr/esl ceramic capacitor is ideal for this function. to mini- mize stray inductance, the capacitor should be placed as close as possible to the ic. this keeps the high frequency content of the input current localized, minimizing radiated and conducted emi while facili- tating optimum performance of the aat1151. ceramic x5r or x7r capacitors are ideal for this function. the size required will vary depending on the load, output voltage, and input voltage source imped- ance characteristics. a typical value is around 10f. the input capacitor rms current varies with the input voltage and the output voltage. the equation for the rms current in the input capacitor is: the input capacitor rms ripple current reaches a maximum when v in is two times the output voltage where it is approximately one half of the load cur- rent. losses associated with the input ceramic capacitor are typically minimal and are not an issue. proper placement of the input capacitor can be seen in the reference design layout in figures 2 and 4. output capacitor since there are no external compensation compo- nents, the output capacitor has a strong effect on loop stability. lager output capacitance will reduce the crossover frequency with greater phase mar- gin. for the 1.5v 1a design using the 4.1h induc- tor, two 22f capacitors provide a stable output. in addition to assisting stability, the output capacitor limits the output ripple and provides holdup during large load transitions. the output capacitor rms ripple current is given by: for a ceramic capacitor, the esr is so low that dis- sipation due to the rms current of the capacitor is not a concern. tantalum capacitors with sufficiently low esr to meet output voltage ripple require- ments also have an rms current rating well beyond that actually seen in this application. layout figures 2 through 5 display the suggested pcb layout for the aat1151. the following guidelines should be used to help ensure a proper layout. ? the input capacitor (c1) should connect as closely as possible to v power (pin 5) and p gnd (pin 8). ? c2 and l1 should be connected as closely as possible. the connection l1 to the lx node should be as short as possible. ? the feedback trace (pin 1) should be sepa- rate 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. ? the resistance of the trace from the load return to the pgnd (pin 8) should be kept to a minimum. this will help to minimize any error in dc regulation due to differences in the potential of the internal signal ground and the power ground. ? low pass filter r1 and c3 provide a cleaner bias source for the aat1151 active circuitry. c3 should be placed as closely as possible to sgnd (pin 2) and v cc (pin 4). see figures 2 and 7. 1 23 v out (v in - v out ) rms in i lfv = ?? i rms = i o 1 - ?? v o v in v o v in
aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 11 figure 2: msop evaluation figure 3: msop evaluation board top layer. board bottom layer. figure 4: qfn evaluation board figure 5: qfn evaluation board top side. bottom side. figure 6: r3 vs. v out for adjustable output figure 7: adjustable output schematic. using the aat1151-1.0v. l1 3.3 h c2, c4 2x 22 f c1 10 f r1 100 c3 0.1 f c1 murata 10 f 6.3v x5r grm42-6x5r106k6.3 l1 sumida cdrh3d16-3r3 nc r2 100k c2, c4 murata 22 f 6.3v grm21br60j226me39l x5r 0805 vo+ 1.25v 0.7a 2.7v-5.5v v- fb 1 gnd 2 en 3 vcc 4 vp 5 lx 6 lx 7 pgnd 8 aat1151-1.0 r3 2.55k 1% r4 10k ? 1% 0 5 10 15 20 25 30 35 40 45 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 output voltage (v) r3 (k ? ) r4=10k ?
aat1151 850khz 700ma synchronous buck dc/dc converter 12 1151.2005.11.1.4 thermal calculations there are two types of losses associated with the aat1151 output switching mosfet: switching loss- es and conduction losses. conduction losses are associated with the r ds(on) characteristics of the output switching device. at the full load condition, assuming continuous conduction mode (ccm), a simplified form of the total losses is given by: where i q is the aat1151 quiescent current. once the total losses have been determined, the junction temperature can be derived from the ja for the msop-8 package. adjustable output for applications requiring an output other than the fixed available, the 1v version can be programmed externally. resistors r3 and r4 of figure 7 force the output to regulate higher than 1 volt. r4 should be 100 times less than the 1m ? internal resistance of the fb pin (recommended 10k ? ). once r4 is selected, r3 can be calculated. for a 1.25 volt out- put with r4 set to 10.0k ? , r3 is 2.55k ? . r3 = (v o - 1) r4 = 0.25 10k ? = 2.55k ? t j = p ja + t amb sw o in in i o 2 (r dson(hs) v o + r dson(ls) (v in v o )) p = fi v v + i q ) v in + (t
aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 13 design example specifications i out 0.7a i ripple 40% of full load at max v in v out 1.5v v in 2.7v to 4.2v (3.6v nominal) f s 850khz t amb 85c maximum input capacitor ripple: inductor selection: select sumida inductor cdrh3d16 3.3h 63m ? 1.8mm height. output capacitor ripple current: 1 23 1 1.5v (4.2v - 1.5v) 3.3 h 850khz 4.2v 23 rms in i lfv = = 99marms v out (v in - v out ) = pesr = esr i rms 2 = 5m ? 99 2 ma = 50 w v o v o 1.5 v 1.5v ? i = ? 1 - = ? 1- = 340ma l ? f v in 3.3 h ? 850khz 4.2v i pk = i out + ? i = 0.7a + 0.17a = 0.87a 2 p = i o 2 ? dcr = (0.7) 2 ? 63m ? = 31mw ? ? ? ? ? ? ? ? v out v out 1.5 v 1.5v l = ? 1 - = ? 1 - = 4.05 h i o ? k ? f v in 0.7a ? 0.4 ? 850khz 4.2v ? ? ? ? ? ? ? ? 1 0.35arms, v in = 2 v o oo rms o in in vv ii vv ?? = -= ?? p = esr i rms 2 = 5m ? 0.35 2 a = 0.6mw
aat1151 850khz 700ma synchronous buck dc/dc converter 14 1151.2005.11.1.4 aat1151 dissipation: surface mount inductors surface mount capacitors manufacturer part number value voltage temp. co. case murata grm40 x5r 106k 6.3 10f 6.3v x5r 0805 murata grm42-6 x5r 106k 6.3 10f 6.3v x5r 1206 murata grm21br60j226me39l 22f 6.3v x5r 0805 murata grm21br60j106me39l 10f 6.3v x5r 0805 max dc size (mm) manufacturer part number value current dcr ( ? ? )l w h type taiyoyuden npo5db4r7m 4.7h 1.4a 0.038 5.9 x 6.1 x 2.8 shielded toko a914byw-3r5m-d52lc 3.5h 1.34a 0.073 5.0 x 5.0 x 2.0 shielded sumida cdrh5d28-3r0 3.0h 2.4a 0.024 5.7 x 5.7 x 3.0 shielded sumida cdrh5d28-4r2 4.2h 2.2a 0.031 5.7 x 5.7 x 3.0 shielded sumida cdrh5d18-4r1 4.1h 1.95a 0.057 5.7 x 5.7 x 2.0 shielded murata lqh55dn4r7m03 4.7h 2.7a 0.041 5.0 x 5.0 x 4.7 non-shielded murata lqh66sn4r7m03 4.7h 2.2a 0.025 6.3 x 6.3 x 4.7 shielded murata cdrh3d16-3r3 3.3h 1.1a 0.063 3.8 x 3.8 x 1.8 shielded t j(max) = t amb + ja p loss = 85 c + 150 c/w 0.145w = 107 c (msop-8) = 85 c + 50 c/w 0.145w = 92 c (qfn33-16) p total + (t sw f i o + i q ) v in i o 2 (r dson(h) v o + r dson(l) (v in -v o )) v in = = + (20nsec 850khz 0.7a + 0.3ma) 4.2v = 0.145w (0.7a) 2 (0.2 ? 1.5v + 0.187 ? (4.2v - 1.5v)) 4.2v
ordering information package information msop-8 all dimensions in millimeters. pin 1 1.95 bsc 0.254 bsc 0.155 0.075 0.60 0.20 3.00 0.10 0.95 0.15 0.95 ref 0.85 0.10 3.00 0.10 10 5 4 4 0.65 bsc 0.30 0.08 0.075 0.075 4.90 0.10 gauge plane output voltage 1 package marking 2 part number (tape and reel) 3 1.0v (adj v out 1.0v) msop-8 jhxyy aat1151iks-1.0-t1 1.0v (adj v out 1.0v) qfn33-16 jhxyy aat1151ivn-1.0-t1 1.8v msop-8 jixyy aat1151iks-1.8-t1 1.8v qfn33-16 jixyy aat1151ivn-1.8-t1 2.5v msop-8 jjxyy aat1151iks-2.5-t1 2.5v qfn33-16 jjxyy aat1151ivn-2.5-t1 3.3v msop-8 nkxyy aat1151iks-3.3-t1 aat1151 850khz 700ma synchronous buck dc/dc converter 1151.2005.11.1.4 15 1. contact local sales office for custom options. 2. xyy = assembly and date code. 3. sample stock is generally held on part numbers listed in bold .
aat1151 850khz 700ma synchronous buck dc/dc converter 16 1151.2005.11.1.4 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737-4600 fax (408) 737-4611 qfn33-16 all dimensions in millimeters. 3.000 0.05 pin 1 dot by marking 1.55 0.15 0.400 0.05 3.000 0.05 0.500 0.05 0.850 0.05 pin 1 identification 0.025 0.025 0.203 0.0254 0.230 0.05 top view bottom view side view 1 13 5 9 ? advanced analogic technologies, inc. analogictech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an analogictech pr oduct. no circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. analogictech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information b eing relied on is current and complete. all products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warran ty, patent infringement, and limitation of liability. analogictech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with anal ogictech?s standard warranty. testing and other quality con- trol techniques are utilized to the extent analogictech deems necessary to support this warranty. specific testing of all param eters of each device is not necessarily performed.

▲Up To Search▲

Price & Availability of AAT1151IKS-10-T1

	To Download AAT1151IKS-10-T1 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .