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general description the aat1210 is a high power dc/dc boost (step-up) converter with an input voltage range from 2.7 to 5.5v. the output voltage can be set from v in + 0.5v to 18v. the total solution is less than 1mm in height. high operating efficiency makes the aat1210 the ideal solution for battery powered and consumer applications. the step-up converter operates at frequencies up to 2mhz, enabling ultra-small external filtering compo- nents. hysteretic current mode control provides excellent transient response with no external com- pensation, achieving stability across a wide operating range with minimal design effort. the aat1210 true load disconnect feature extends battery life by isolating the load from the power source when the en/set pin is pulled low, ensuring zero volts output during the disable state. this fea- ture eliminates the external boost converter leakage path and achieves standby quiescient current <1a without an external switching device. a fixed output voltage is set using two external resis- tors. alternatively, the output may be adjusted dynami- cally across a 2.0x range. the output can toggle between two preset voltages using the sel logic pin. optionally, the output can be dynamically set to any one of 16 programmed levels using analogictech's patented simple serial control? (s 2 cwire?) interface. the aat1210 is available in a pb-free, thermally- enhanced 16-pin 3x4mm tdfn low-profile package and is rated over the -40c to +85c temperature range. features ?v in range: 2.7v to 5.5v ? maximum continuous output ? 900ma at 5v ? 300ma at 12v ? 150ma at 18v ? up to 2mhz switching frequency ? ultra-small inductor and capacitors ? 1mm height inductor ? small ceramic capacitors ? hysteretic current mode control ? no external compensation ? excellent transient response ? high efficiency at light load ? up to 90% efficiency ? integrated low r ds(on) mosfet switches ? low inrush with integrated soft start ? cycle-by-cycle current limit ? short-circuit and over-temperature protection ? true load disconnect ? optional dynamic voltage programming ? tdfn34-16 package ? -40c to +85c temperature range applications ? gps systems ? dvd blu-ray ? handheld pcs ? pda phones ? portable media players ? usb otg aat1210 high power dc/dc boost converter with optional dynamic voltage programming typical application 1210.2007.02.1.2 1 switchreg ? aat1210 boost converter output capability (tdfn34-16; t amb = 25 c; t c(rise) = +50 0 200 400 600 800 1000 1200 1400 56789101112131415161718 7 v in = 4.5v v in = 3.6v v in = 2.7v fb2 vin en/set gnd fb1 lin sw d1 sel aat1210 tdfn34-16 l1 0.47h v out 5v @ 900m a v in 3.6v c1 4.7f 0603 r3 4.99k r2 40.2k c2 10f 0603
pin descriptions pin configuration tdfn34-16 (top view) pin # symbol function 1, 2 lin switched power input. connect to the power inductor. 3 fb1 feedback pin for high output voltage set point. pin set to 1.2v when sel is high and disabled when sel is low. disabled with s 2 cwire control. tie directly to fb2 pin for static (fixed) output voltage. 4 fb2 feedback pin for low output voltage set point. pin set to 0.6v when sel is low and disabled when sel is high. voltage is set from 0.6v to 1.2v with s 2 cwire control. tie directly to fb1 pin for static (fixed) output voltage. 5 gnd ground pin. 6, 7, 8 pgnd power ground for the boost converter; connected to the source of the n-channel mosfet. connect to the input and output capacitor return. 9, 10 sw boost converter switching node. connect the power inductor between this pin and the lin pin. 11 n/c no connection. 12 vin input voltage for the converter. connect this pin directly to the vp pin. 13 sel logic high selects fb1 high output reference. logic low selects fb2 low output reference. pull low for s 2 cwire control. 14 en/set active high enable pin. alternately, input pin for s 2 cwire control using the fb2 reference. 15, 16 vp input power pin; connected internally to the source of the p-channel mosfet. connect externally to the input capacitor(s). ep exposed paddle (bottom). c onnected internally to the sw pins. can be tied to bottom side pcb heat sink to optimize thermal performance. aat1210 high power dc/dc boost converter with optional dynamic voltage programming 2 1210.2007.02.1.2 fb1 fb2 gnd lin lin 3 pgnd pgnd pgnd en/set sel vin vp vp n/c sw sw 4 5 1 2 6 7 8 14 13 12 16 15 11 10 9
absolute maximum ratings 1 recommended operating conditions symbol description value units ja thermal resistance 44 c/w p d maximum power dissipation (t a = 25oc) 2270 mw symbol description value units vin, vp input voltage -0.3 to 6.0 v sw switching node 20 v lin, en/set, maximum rating v in + 0.3 v sel, fb1, fb2 t j operating temperature range -40 to 150 c t s storage temperature range -65 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 3 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.
electrical characteristics 1 v in = 3.6v, t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units power supply v in input voltage range 2.7 5.5 v v out output voltage range v in + 18 v 0.5v v in = 2.7v, v out = 5v 600 i out(max) output current 2 v in = 2.7v, v out > 5v see note 2 ma v in = 3.6v, v out > 5v 900 v in rising 2.7 v v uvlo uvlo threshold hysteresis 150 mv v in falling 1.8 v sel = gnd, v out = 5v, 250 a i q quiescent current no load, switching 3 sel = gnd, fb2 = 1.5v, 40 70 a not switching i shdn vin pin shutdown current en/set = gnd 1.0 a fb1 fb1 reference voltage i out = 0 to i out(max) ma, 1.164 1.2 1.236 v v in = 2.7v to 5.0v, sel = high fb2 fb2 reference voltage i out = 0 to i out(max) ma, 0.582 0.6 0.618 v v in = 2.7v to 5.0v, sel = low v loadreg load regulation i out = 0 to i out(max) ma 0.01 %/ma v linereg /v in line regulation v in = 3.0v to 5.5v 0.6 %/v r ds(on)l low side switch on 0.06 resistance r ds(on)in input disconnect switch 0.18 on resistance t ss soft-start time from enable to output regulation; 2.5 ms v out = 15v , c out = 10f t sd over-temperature 140 c shutdown threshold t hys shutdown hysteresis 15 c i lim n-channel current limit v in = 3.6v , l =2.2h 3.0 a aat1210 high power dc/dc boost converter with optional dynamic voltage programming 4 1210.2007.02.1.2 1. specifications over the -40c to +85c operating temperature range are assured by design, characterization and correlation w ith sta- tistical process controls. 2. maximum output power and current is dependent upon operating efficiency and thermal/mechanical design. output current and o ut- put power derating may apply. see figure 1. 3. total input current with prescribed fb resistor network can be reduced with larger resistor values.
electrical characteristics 1 v in = 3.6v, t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units sel, en/set v sel(l) sel threshold low v in = 2.7v 0.4 v v sel(h) sel threshold high v in = 5.5v 1.4 v v en/set(l) enable threshold low v in = 2.7v 0.4 v v en/set(h) enable threshold high v in = 5.5v 1.4 v t en/set lo en/set low time 0.3 75 s t en/set hi min minimum en/set high time 50 ns t en/set hi max maximum en/set high time 75 s t off en/set off timeout 500 s t lat en/set latch timeout 500 s i en/set en/set input leakage -1 1 a aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 5 1. specifications over the -40c to +85c operating temperature range are assured by design, characterization and correlation w ith sta- tistical process controls.
typical characteristics aat1210 high power dc/dc boost converter with optional dynamic voltage programming 6 1210.2007.02.1.2 dc regulation (v out = 12v) output current (ma) output error (%) -5 -4 -3 -2 -1 0 1 2 0.1 1 10 100 1000 v in = 5.5v v in = 4.5v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. load (v out = 12v) output current (ma) efficiency (%) 25 35 45 55 65 75 85 95 0.1 1 10 100 1000 v in = 5.5v v in = 4.5v v in = 4.2v v in = 3.6v dc regulation (v out = 9v) output current (ma) output error (%) -5 -4 -3 -2 -1 0 1 2 0.1 1 10 100 1000 v in = 5.5v v in = 4.5v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. load (v out = 9v) output current (ma) efficiency (%) 25 35 45 55 65 75 85 95 0.1 1 10 100 1000 v in = 5.5v v in = 4.5v v in = 4.2v v in = 3.6v dc regulation (v out = 5v) output current (ma) output error (%) -5 -4 -3 -2 -1 0 1 2 0.1 1 10 100 1000 v in = 4.5v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. load (v out = 5v) output current (ma) efficiency (%) 25 35 45 55 65 75 85 95 0.1 1 10 100 1000 v in = 4.5v v in = 4.2v v in = 3.6v
typical characteristics aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 7 no load input current vs. temperature (v in = 3.6v; v out = 5v) temperature ( c) supply current (ma) 0.25 0.26 0.27 0.28 0.29 0.3 0.31 0.32 0.33 0.34 -40 -15 10 35 60 8 5 no load input current vs. input voltage (en = high) input voltage (v) supply current (ma) 0 0.5 1 1.5 2 2.5 3 2.5 3 3.5 4 4.5 5 5.5 6 v out = 18v v out = 9v v out = 5v v out = 12v output voltage error vs. temperature (v in = 3.6v; v out = 12v; i out = 100ma) temperature ( c) output error (%) -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -40 -15 10 35 60 8 5 line regulation (v out = 12v) input voltage (v) accuracy (%) -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 v in = 2.7v v in = 3.0v v in = 3.6v v in = 5.5v v in = 4.2v dc regulation (v out = 15v) output current (ma) output error (%) v in = 4.5v -5 -4 -3 -2 -1 0 1 2 0.1 1 10 100 1000 v in = 5.5v v in = 4.2v v in = 3.6v v in = 3.0v v in = 2.7v efficiency vs. load (v out = 15v) output current (ma) efficiency (%) 25 35 45 55 65 75 85 95 0.1 1 10 100 1000 v in = 5.5v v in = 4.5v v in = 4.2v v in = 3.6v
typical characteristics aat1210 high power dc/dc boost converter with optional dynamic voltage programming 8 1210.2007.02.1.2 load transient response (v in = 3.6v; v out = 12v; i out = 0ma to 200ma) time (20s/div) output current (a) (middle) inductor current (a) (bottom) output voltage (top) (v) 10.8 11 11.2 11.4 11.6 11.8 12 12.2 12.4 -1 0 1 2 3 4 5 6 7 0ma 200ma load transient response (v in = 3.6v; v out = 5v; i out = 120ma to 360ma) time (20s/div) output current (a) (middle) inductor current (a) (bottom) output voltage (top) (v) 4.65 4.7 4.75 4.8 4.85 4.9 4.95 5 5.05 -1 0 1 2 3 4 5 6 7 120ma 360ma load transient response (v in = 3.6v; v out = 5v; i out = 0ma to 600ma) time (20s/div) output current (a) (middle) inductor current (a) (bottom) output voltage (top) (v) 3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 -1 0 1 2 3 4 5 6 7 0ma 600ma output ripple (v in = 3.6v; v out = 15v; no load; l = 1.2h) time (200ns/div) inductor current (bottom) (a) output voltage (top) (v) 14.7 14.75 14.8 14.85 14.9 14.95 15 15.05 15.1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 output ripple (v in = 3.6v; v out = 15v; i out = 150ma; l = 1.2h) time (500ns/div) inductor current (bottom) (a) output voltage (top) (v) 14.7 14.75 14.8 14.85 14.9 14.95 15 15.05 15.1 -4 -2 0 2 4 6 8 10 12 ac output ripple vs. output current (v out = 9v) output current (ma) output voltage (mv) 0 10 20 30 40 50 60 70 0 50 100 150 200 250 300 v in = 2.7v v in = 3.0v v in = 3.6v v in = 4.2v v in = 5.5v
typical characteristics aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 9 soft start (v in = 3.6v; c in = 2.2f; i out = 100ma; v out = 15v) time (500s/div) input current (bottom) (a) enable voltage (middle) (v) output voltage (top) (v) -20 -15 -10 -5 0 5 10 15 20 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 1.04v n-channel r ds(on) vs. input voltage input voltage (v) r ds(on) (m ) 40 50 60 70 80 90 100 110 2.5 3 3.5 4 4.5 5 5.5 6 120 c 100 c 85 c 25 c p-channel r ds(on) vs. input voltage input voltage (v) r ds(on) (m ) 100 120 140 160 180 200 220 240 260 280 300 2.5 3 3.5 4 4.5 5 5.5 6 120 c 100 c 85 c 25 c line response (v out = 5v @ 100ma) time (100s/div) input voltage (bottom) (v) output voltage (top) (v) 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 2.4 3 3.6 4.2 4.8 5.4 6 6.6 7.2 line response (v out = 15v @ 100ma) time (100s/div) input voltage (bottom) (v) output voltage (top) (v) 13.5 13.75 14 14.25 14.5 14.75 15 15.25 15.5 2.4 3 3.6 4.2 4.8 5.4 6 6.6 7.2 load transient response (v in = 3.6v; v out = 12v; i out = 40 to 120ma) time (20s/div) output current (middle) (a) inductor current (bottom) (a) output voltage (top) (v) 10.8 11 11.2 11.4 11.6 11.8 12 12.2 12.4 -1 0 1 2 3 4 5 6 7 120ma 40ma
typical characteristics aat1210 high power dc/dc boost converter with optional dynamic voltage programming 10 1210.2007.02.1.2 10 1210.2007.02.1.2 soft start (v in = 3.6v; c in = 2.2f; i out = 100ma; v out = 5v) time (500s/div) input current (bottom) (a) output voltage (top) (v) enable voltage (middle) (v) -8 -6 -4 -2 0 2 4 6 8 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 1.04v
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 11 functional description the aat1210 consists of a dc/dc boost (step-up) controller, an integrated slew rate controlled input disconnect mosfet switch, and a mosfet power switch. a high voltage rectifier, power inductor, capacitors and resistor divider network are required to implement a dc/dc boost converter. the mini- mum output voltage must be 0.5v above the input voltage and the maximum output voltage is 18v. the operating input voltage range is 2.7v to 5.5v. control loop the aat1210 provides the benefits of current mode control with a simple hysteretic feedback loop. the device maintains exceptional dc regula- tion, transient response, and cycle-by-cycle current limit without additional compensation components. the aat1210 modulates the power mosfet switching current in response to changes in output voltage. this allows the voltage loop to directly pro- gram the required inductor current in response to changes in the output load. the switching cycle initiates when the n-channel mosfet is turned on and current ramps up in the inductor. the on interval is terminated when the inductor current reaches the programmed peak current level. during the off interval, the input cur- rent decays until the lower threshold, or zero induc- tor current, is reached. the lower current is equal to the peak current minus a preset hysteresis threshold, which determines the inductor ripple cur- rent. the peak current is adjusted by the controller until the output current requirement is met. the magnitude of the feedback error signal deter- mines the average input current. the aat1210 controller implements a programmed current source connected to the output capacitor and load resistor. there is no right-half plane zero, and loop stability is achieved with no additional compensa- tion components. functional block diagram gnd sel fb2 fb1 en/set vp lin control soft-start timer output select v ref1 v ref2 vin s w pgnd
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 12 1210.2007.02.1.2 increased load current results in a drop in the out- put feedback voltage (fb1 or fb2) sensed through the feedback resistors (r1, r2, r3 in figure 2). the controller responds by increasing the peak inductor current, resulting in higher average current in the inductor. alternatively , decreased output load results in an increase in the output feedback voltage. the controller responds by decreasing the peak inductor current, resulting in lower average current in the inductor. at light load, the inductor off interval current goes below zero, which terminates the off period, and the boost converter enters discontinuous mode opera- tion. further reduction in the load results in a corre- sponding reduction in the switching frequency. the aat1210 provides optimized light load operation which reduces switching losses and maintains the highest possible efficiency at light load. the aat1210 switching frequency varies with changes in the input voltage, output voltage, and inductor size. once the boost converter has reached continuous mode, further increases in the output load will not significantly change the operat- ing frequency and constant ripple current in the boost inductor is maintained. output voltage programming the fb reference voltage is determined by the logic state of the sel pin. the output voltage is pro- grammed through a resistor divider network (r1, r2, r3) from the positive output terminal to fb1/fb2 pins to ground. pulling the sel pin high activates the fb1 pin which maintains a 1.2v reference voltage, while the fb2 reference is disabled. pulling the sel pin low activates the fb2 pin which maintains a 0.6v reference, while the fb1 reference is disabled. the fb1 and fb2 pins may be tied together when a stat- ic dc output voltage is desired. toggling the sel pin programs the output voltage between two distinct output voltages across a 2.0x range (maximum). with fb1, fb2 tied together, the output voltage toggles between two voltages with a 2.0x scaling factor. an additional resistor between fb1 and fb2 pins allows toggling between two voltages with a <2.0x scaling factor. alternatively, the output voltage may be dynamical- ly programmed to any of 16 voltage levels using the s 2 cwire serial digital input. the single-wire s 2 cwire interface provides high-speed output voltage pro- grammability across a 2.0x output voltage range. s 2 cwire functionality is enabled by pulling the sel pin low and providing s 2 cwire digital clock input to the en/set pin which sets the fb2 voltage level from 0.6v to 1.2v. table 6 details the fb2 refer- ence voltage versus s 2 cwire rising clock edges. soft start / enable the input disconnect switch is activated when a valid input voltage is present and the en/set pin is pulled high. the slew rate control on the p-channel mosfet ensures minimal inrush current as the output voltage is charged to the input voltage, prior to switching of the n-channel power mosfet. monotonic turn-on is guaranteed by the integrated soft-start circuitry. soft-start time of approximately 2.5ms is internally programmed to minimize inrush current and elimi- nate output voltage overshoot across the full input voltage range under all loading conditions. current limit and over-temperature protection the switching of the n-channel mosfet termi- nates if the current limit of 3.0a (minimum) is exceeded. this minimizes power dissipation and component stresses under overload and short-cir- cuit conditions. switching resumes when the cur- rent decays below the current limit. thermal protection disables the aat1210 if internal power dissipation becomes excessive. thermal pro- tection disables both the n-channel and p-channel mosfets. the junction over-temperature threshold is 140c with 15c of hysteresis. the output voltage automatically recovers when the over-temperature or over-current fault condition is removed. under-voltage lockout internal bias of all circuits is controlled via the vin input. under-voltage lockout (uvlo) guarantees sufficient v in bias and proper operation of all inter- nal circuitry prior to activation.
applications information output current and power capability the aat1210 boost converter provides a high volt- age, high current, regulated dc output voltage from a low voltage dc input. the operating input voltage range is 2.7 to 5.5v. figure 1 details the output current and power capability of the aat1210 for output voltages from 5v to 18v with dc input of 2.7v, 3.6v and 4.5v. the maximum output current/power curves are based on +50oc case temperature rise over ambi- ent using the tdfn34-16 package. ambient tem- perature at 25oc, natural convection is assumed. up to 1.3a of output current is possible with 4.5v input voltage. as shown in figure 1, the output capability is somewhat reduced at higher output voltage and reduced input voltage. the aat1210 schematic and pcb layout are pro- vided in figures 2, 6, and 7. the pcb layout includes a small 1 ounce copper power plane on top and bottom layers which is tied to the paddle of the tdfn34-16 package. the top plane is soldered directly to the paddle, and tied to the bottom layer with plated through vias. details of the pcb layout are provided in figures 6, 7, and 8. actual case temperature may vary and depends on the boost converter efficiency and the system ther- mal design; including, but not limited to airflow, local heat sources, etc. additional derating may apply. selecting the output diode to ensure minimum forward voltage drop and no recovery, a high voltage schottky diode is consid- ered the best choice for use with the aat1210 boost converter. the aat1210 output diode is sized to maintain acceptable efficiency and reasonable operating junction temperature under full load oper- ating conditions. forward voltage (v f ) and package thermal resistance ( ja ) are the dominant factors to consider in selecting a diode. the diode's pub- lished current rating may not reflect actual operating conditions and should be used only as a compara- tive measure between similarly rated devices. 20v rated schottky diodes are recommended for out- puts less than 15v, while 30v rated schottky diodes are recommended for outputs greater than 15v. aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 13 figure 1: maximum output power vs. output voltage for t c(rise) = +50oc (assumes tdfn34-16 paddle heatsinking; see figures 6, 7, and 8). aat1210 boost converter maximum output capability output voltage (v) maximum output current (ma) maximum output power (w) 0 200 400 600 800 1000 1200 1400 5 6 7 8 91011 1213 1415 1617 18 0 1 2 3 4 5 6 7 v in = 4.5v v in = 3.6v output current output power v in = 2.7v
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 14 1210.2007.02.1.2 figure 2: aat1210 demo board schematic. the switching period is divided between on and off time intervals. during the on time, the n-channel power mosfet is conducting and storing energy in the boost inductor. during the off time, the n-channel power mosfet is not conducting. stored energy is transferred from the input supply and boost inductor to the output load through the output diode. duty cycle is defined as the on time divided by the total switching interval. the maximum duty cycle can be estimated from the relationship for a continuous mode boost con- verter. maximum duty cycle (d max ) is the duty cycle at minimum input voltage (v in(min) ). the average diode current during the off time can be estimated. the following curves show the v f characteristics for different schottky diodes (100c case). the v f of the schottky diode can be estimated from the average current during the off time. d1 schottky 1 2 3 enable jp1 1 2 3 select jp2 4.7uf c1 u1 aat1210 tdfn34-16 c1 6.3v 0603 4.7f c2 10v 0805 10f d1 30v 0.5a mbr0530t1 sod-123 l1 0.47h sd10-r47-r r1 36.5k 0603 r2 549 0603 r3 4.99k 0603 r4 10k 0603 vp 16 vp 15 en/set 14 sel 13 pgnd 8 pgnd 7 pgnd 6 gnd 5 fb2 4 fb1 3 lin 2 lin 1 vin 12 n/c 11 sw 10 sw 9 aat1210_tdfn34-16 u1 vin: 2.7v to 5.5v c2 4.7f 10v r2 549 r1 36.5k r3 4.99k 9v at 300ma 5v at 600ma l1 0.47h r4 10k i out 1 - d max i avg(off) = v out - v in(min) v out d max = t on t on + t off d = = t on ? f s = t on + t off 1 f s
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 15 figure 3: forward voltage vs. forward current for various schottky diodes. the average diode current is equal to the output current. the average output current multiplied by the for- ward diode voltage determines the loss of the out- put diode. diode junction temperature can be estimated. the junction temperature should be maintained below 110oc, but may vary depending on applica- tion and/or system guidelines. the diode ja can be minimized with additional pcb area on the cath- ode. pcb heatsinking the anode may degrade emi performance. the reverse leakage current of the rectifier must be considered to maintain low quiescent (input) cur- rent and high efficiency under light load. the recti- fier reverse current increases dramatically at high temperatures. additional considerations may apply to satisfy short circuit conditions. a short circuit across the output terminals results in high currents through the induc- tor and output diode. the output diode must be sized to prevent damage and possible failure of the diode under short circuit conditions. the inductor may saturate without incurring damage. when current limit of (3a minimum) is reached, switching of the low side n-channel mosfet is disabled. although switching is disabled, dc cur- rent continues to build to a level determined by the dc resistance in the path of current flow. for portable applications, the source resistance (r source ) of the li-ion battery pack is between 100-300m and should also be considered. the aat1210 controller will generate an over-tem- perature (ot) event under extended short circuit conditions. ot disables the high side p-channel mosfet, which terminates current flow in the out- put diode. current flow continues when ot hys- teresis (cool-down) is met. this continues until the short circuit condition is removed. in portable appli- cations, the battery pack over-current protection may be enabled prior to an ot event. table 1: typical surface mount schottky rectifiers for various output levels. rated non-repetitive thermal part forward peak surge rated resistance manufacturer number current (a) current (a) voltage (v) ( ja , c/w) case diodes, inc. bat42w 0.2 4.0 30 500 sod-123 on semi mbr0530t 0.5 5.5 30 206 sod-123 zetex zhcs350 0.35 4.2 40 330 sod-523 central semi cmdsh2-3 0.2 1.0 30 500 sod-323 i sht-ckt(max) = (v in(max) - v f ) (r source + r dc + r ds(on)in ) t j = t amb + ja p loss_diode p loss_diode = i avg v f = i out v f i avg(tot) = i out forward voltage (v) forward current (ma) 10 100 1000 10000 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 b340la mbr0530 zhcs350 bat42w
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 16 1210.2007.02.1.2 table 2: output inductor and capacitor values vs. output voltage v out c1 (input capacitor) c2 (output capacitor) l1 (boost inductor) 5.0 4.7f 10f/6.3v, 10v 0.47h 9.0 4.7f 10f/10v 0.47h 12.0 4.7f 10f/16v 1.0/1.2h 15.0 4.7f 10f/16v 1.0/1.2h 18.0 4.7f 4.7f/25v 2.2h the diode non-repetitive peak surge current (i fsm ) rating should be greater than i sht_ckt(max) to ensure diode reliability under short circuit condi- tions. typically, i fsm current is specified for con- duction periods from 8-10ms. if short circuit surviv- ability is required, it is recommended to verify i sht_ckt(max) under actual operating conditions across the expected operating temperature range. selecting the boost inductor the aat1210 controller utilizes hysteretic control and the switching frequency varies with output load and input voltage. the value of the inductor deter- mines the maximum switching frequency of the boost converter. increased output inductance decreases the switching frequency, resulting in higher peak currents and increased output voltage ripple. the required inductance increases with increasing output voltage. the inductor is sized from 0.47h to 2.2h for output voltages from 5v to 18v. this selection maintains high frequency switching (up to 2mhz), low output ripple and min- imum solution size. a summary of recommended inductors and capacitors for 5v to 18v fixed out- puts is provided in table 2. the physical size of the inductor may be reduced when operating at greater than 2.7v input voltage and/or less than maximum rated output power is desired (see figure 1 for maximum output power estimate). figure 4 provides the peak inductor cur- rent (i peak ) versus output power for different input voltage levels. the curves are valid for all output voltages and assume the corresponding induc- tance value provided in figure 4. the inductor is selected to maintain i peak current less than the specified saturation current (i sat ). figure 4: peak inductor current (i peak ) vs. output power. the rms current flowing through the boost inductor is equal to the dc plus ac ripple components. under worst-case rms conditions, the current wave- form is critically continuous. the resulting rms cal- culation yields worst-case inductor loss. the rms value should be compared against the manufactur- er's temperature rise, or thermal derating, guidelines. in most cases, the inductor's specified i rms current will be greater than the i rms current required by the boost inductor. for a given inductor type, smaller inductor size leads to an increase in dcr winding resistance and, in most cases, increased thermal impedance. winding resistance degrades boost converter efficiency and increases the inductor operating temperature. p loss_inductor = i rms 2 dcr i peak i rms = 3 aat1210 peak inductor current vs. output power output power (w) peak inductor current (ma) 0 500 1000 1500 2000 2500 3000 3500 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 v in = 4.5v v in = 3.6v v in = 2.7v
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 17 table 3: recommended inductors. table 4: recommended mlc capacitors. value voltage rating manufacturer part number (f) (v) temp. co. case size grm188r60j475kead 4.7 6.3 x5r 0603 grm21br61a475ka73l 4.7 10 x5r 0805 murata grm21br61e475ka12l 4.7 25 x5r 0805 www.murata.com grm188r60j106me47d 10 6.3 x5r 0603 grm21br61a106ke19l 10 10 x5r 0805 grm219r61a106ke44d 10 10 x5r 0805 (h = 0.85mm) grm21br61c106ke15l 10 16 x5r 0805 max max dc i sat i rms size inductance current current dcr lxwxh manufacturer part number (h) (a) (a) (m ) (mm) type cdrh5d16-1r4 1.4 4.7 4.7 14.6 5.8x5.8x1.8 shielded sumida cdrh5d16-1r4 2.2 3.0 2.85 35.9 5.8x5.8x1.8 shielded www.sumida.com cdrh3d11/hp-1r5 1.5 2.0 1.45 80 4.0x4.0x1.2 shielded cdrh3d11/hp-2r7 2.7 1.55 1.3 100 4.0x4.0x1.2 shielded lqh55dnr47m03 0.47 4.8 - 13 5.7x5.0x4.7 non-shielded murata lqh55dn1r0m03 1.0 4.0 - 19 5.7x5.0x4.7 non-shielded www.murata.com lqh55dn1r5m03 1.5 3.7 - 22 5.7x5.0x4.7 non-shielded lqh55dn2r2m03 2.2 3.2 - 29 5.7x5.0x4.7 non-shielded sd3814-r47 0.47 4.44 2.81 20 4.0x4.0x1.4 shielded sd3814-1r2 1.2 2.67 1.85 46 4.0x4.0x1.4 shielded cooper sd3814-2r2 2.2 1.9 1.43 77 4.0x4.0x1.4 shielded www.cooperet.com sd10-r47-r 0.47 3.54 2.59 24.9 5.2x5.2x1.0 shielded sd10-1r0-r 1 2.25 1.93 44.8 5.2x5.2x1.0 shielded sd10-2r2-r 2.2 1.65 1.35 91.2 5.2x5.2x1.0 shielded sd18-2r2-r 2.2 2.16 2.55 39.8 5.2x5.2x1.8 shielded to ensure high reliability, the inductor temperature should not exceed 100oc. manufacturer's recommen- dations should be consulted. in some cases, pcb heatsinking applied to the aat1210 lin node (non- switching) can improve the inductor's thermal capability. pcb heatsinking may degrade emi performance when applied to the sw node (switching) of the aat1210. shielded inductors provide decreased emi and may be required in noise sensitive applications. unshielded chip inductors provide significant space savings at a reduced cost compared to shielded (wound and gapped) inductors. chip-type inductors have increased winding resistance when compared to shielded, wound varieties. selecting dc/dc boost capacitors recommended input and output capacitors for out- put voltages from 5v to 18v are provided in table 4. the high output ripple inherent in the boost converter necessitates low impedance output filtering. multi- layer ceramic (mlc) capacitors provide small size and high capacitance, low parasitic equivalent series resistance (esr) and equivalent series inductance (esl), and are well suited for use with the aat1210 boost regulator. mlc capacitors of type x7r or x5r are recommended to ensure good capacitance stabil- ity over the full operating temperature range.
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 18 1210.2007.02.1.2 the output capacitor is sized to maintain the output load without significant voltage droop ( v out ) during the power switch on interval, when the output diode is not conducting. a ceramic output capacitor from 4.7f to 10f is recommended. output capacitors should be rated from 10v to 25v, depending on the maximum desired output voltage. ceramic capaci- tors sized as small as 0603 are available which meet these requirements. minimum 6.3v rated ceramic capacitors are required at the input. ceramic capacitors sized as small as 0603 are available which meet these requirements. output capacitors should be rated from 6.3v to 25v, depending on the maximum desired output voltage. mlc capacitors exhibit significant capacitance reduction with applied voltage. output ripple meas- urements should confirm that output voltage droop and converter stability is acceptable. voltage derat- ing can minimize this factor, but results may vary with package size and among specific manufacturers. output capacitor size can be estimated at a switch- ing frequency (f sw ) of 500khz (worst-case). the boost converter input current flows during both on and off switching intervals. the input ripple current is less than the output ripple and, as a result, less input capacitance is required. a ceramic output capacitor from 4.7f to 10f is recommend- ed. the voltage rating of the capacitor must be greater than, or equal to, the maximum operating output voltage. x5r ceramic capacitors are avail- able in 6.3v, 10v, 16v and 25v rating. ceramic capacitors sized as small as 0603 are available which meet these requirements. minimum 6.3v rated ceramic capacitors are required at the input. ceramic capacitors sized as small as 0603 are available which meet these requirements. setting the output voltage the minimum output voltage must be greater than the specified maximum input voltage plus 0.5v mar- gin to maintain proper operation of the aat1210 boost converter. the output voltage may be pro- grammed through a resistor divider network located from the output to fb1 and fb2 pins to ground. pulling the sel pin high activates the fb1 pin which maintains a 1.2v reference voltage, while the fb2 reference is disabled. pulling the sel pin low acti- vates the fb2 pin which maintains a 0.6v refer- ence, while the fb1 reference is disabled. the aat1210 output voltage can be programmed by one of three methods. first, the output voltage can be static by pulling the sel logic pin either high or low. second, the output voltage can be dynami- cally adjusted between two pre-set levels within a 2x operating range by toggling the sel logic pin. third, the output can be dynamically adjusted to any of 16 preset levels within a 2x operating range using the integrated s 2 cwire single wire interface via the en/set pin. see table 5 for static and dynamic output voltage settings. table 5 provides details of resistor values for com- mon output voltages from 5v to 18v for sel = high and sel = low options. sel = high corresponds to v out(1) and sel = low corresponds to v out(2) . option 1: static output voltage most dc/dc boost converter applications require a static (fixed) output voltage. if a static voltage is desired, the fb1 pin should be connected directly to fb2 and a resistor between fb1 and fb2 pins is not required. a static output voltage can be configured by pulling the sel either high or low. sel pin high activates the fb1 reference pin to 1.2v (nominal). alternatively, the sel pin is pulled low to activate the fb2 refer- ence at 0.6v (nominal). table 5 provides details of resistor values for common output voltages from 5v to 18v for sel = high and sel = low options. i out d max f s v out c out =
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 19 option 2: dynamic voltage control using sel pin the output may be dynamically adjusted between two output voltages by toggling the sel logic pin. output voltages v out(1) and v out(2) correspond to the two output references, fb1 and fb2. pulling the sel logic pin high activates v out(1) , while pulling the sel logic pin low activates v out(2) . in addition, the ratio of output voltages v out(2) /v out(1) is always less than 2.0, corresponding to a 2x (max- imum) programmable range. option 3: dynamic voltage control using s 2 cwire interface the output can be dynamically adjusted by the host controller to any of 16 pre-set output voltage levels using the integrated s 2 cwire interface. the en/set pin serves as the s 2 cwire interface input. the sel pin must be pulled low when using the s 2 cwire interface. s 2 cwire serial interface analogictech's s 2 cwire serial interface is a propri- etary high-speed single-wire interface. the s 2 cwire interface records rising edges of the en/set input and decodes into 16 different states. each state corresponds to a voltage setting on the fb2 pin, as shown in table 6. s 2 cwire output voltage programming the aat1210 is programmed through the s 2 cwire interface according to table 6. the rising clock edges received through the en/set pin determine the feedback reference and output voltage set- point. upon power-up with the sel pin low and prior to s 2 cwire programming, the default feedback reference voltage is set to 0.6v. table 5: sel pin voltage control resistor values (1% resistor tolerance). v out(1) v out(2) r3 = 4.99k (sel = high) (sel = low) r1 (k ) r2 (k ) 5.0v - 15.8 0 6.0v - 20.0 0 7.0v - 24.3 0 8.0v - 28.0 0 9.0v - 32.4 0 10.0v - 36.5 0 12.0v - 44.2 0 15.0v - 57.6 0 16.0v - 61.9 0 18.0v - 69.8 0 - 5.0v 36.5 0 - 6.0v 45.3 0 - 7.0v 53.6 0 - 8.0v 61.9 0 - 9.0v 69.8 0 - 10.0v 78.7 0 - 12.0v 95.3 0 - 15.0v 121 0 - 16.0v 127 0 - 18.0v 143 0 9.0v 5.0v 36.5 0.549 10.0v 9.0v 66.5 4.02 12.0v 10.0v 75 3.32 15.0v 10.0v 76.8 1.65 15.0v 12.0v 90.9 3.01 16.0v 10.0v 76.8 1.24 18.0v 10.0v 78.7 0.562 15.0v 12.0v 90.9 3.01 16.0v 12.0v 93.1 2.49 18.0v 12.0v 93.1 1.65 18.0v 15.0v 115 3.32
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 20 1210.2007.02.1.2 table 6: s 2 cwire voltage control settings (sel = low). s 2 cwire serial interface timing the s 2 cwire serial interface has flexible timing. data can be clocked-in at speeds up to 1mhz. after data has been submitted, en/set is held high to latch the data for a period t lat . the output is subsequently changed to the predetermined volt- age. when en/set is set low for a time greater than t off , the aat1210 is disabled. when dis- abled, the register is reset to the default value, which sets the fb2 pin to 0.6v if en is subse- quently pulled high. pcb layout boost converter performance can be adversely affected by poor layout. possible impact includes high input and output voltage ripple, poor emi per- formance, and reduced operating efficiency. every attempt should be made to optimize the layout in order to minimize parasitic pcb effects (stray resistance, capacitance, inductance) and emi cou- pling from the high frequency sw node. a suggested pcb layout for the aat1210 boost converter is shown in figures 6, 7, and 8. the fol- lowing pcb layout guidelines should be considered: 1. minimize the distance from capacitor c1 and c2 negative terminal to the pgnd pins. this is especially true with output capacitor c2, which conducts high ripple current from the output diode back to the pgnd pins. 2. place the feedback resistors close to the output terminals. route the output pin directly to resis- tor r1 to maintain good output regulation. r3 should be routed close to the output gnd pin, but should not share a significant return path with output capacitor c2. 3. minimize the distance between l1 to d1 and switching pin sw; minimize the size of the pcb area connected to the sw pin. 4. maintain a ground plane and connect to the ic pgnd pin(s) as well as the gnd terminals of c1 and c2. 5. consider additional pcb area on d1 cathode to maximize heatsinking capability. this may be necessary when using a diode with a high v f and/or thermal resistance. 6. to maximize thermal capacity, connect the exposed paddle to the top and bottom power planes using plated through vias. top and bot- tom planes should not extend far beyond the tdfn34-16 package boundary to minimize stray emi. en/set fb2 en/set fb2 rising reference rising reference edges voltage (v) edges voltage (v) 1 0.60 (default) 9 0.92 2 0.64 10 0.96 3 0.68 11 1.00 4 0.72 12 1.04 5 0.76 13 1.08 6 0.80 14 1.12 7 0.84 15 1.16 8 0.88 16 1.20 figure 5: s 2 cwire timing diagram. 1 en/set 2 n-1 n 16 data reg 0n-1 0 t hi t lo t lat t off
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 21 figure 6: aat1210 evaluation board figure 7: aat1210 evaluation board top side layout. bottom side layout. figure 8: exploded view of aat1210 evaluation board top side layout detailing plated through vias.
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 22 1210.2007.02.1.2 ordering information package information 3 tdfn34-16 all dimensions in millimeters. package marking 1 part number (tape and reel) 2 tdfn34-16 vdxyy aat1210irn-0.6-t1 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 re quired to ensure a proper bottom solder connection. 3.000 all analogictech products are offered in pb-free packaging. the term ?pb-free? means semiconductor products that are in compliance with current rohs standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. for more information, please visit our website at http://www.analogictech.com/pbfree.
aat1210 high power dc/dc boost converter with optional dynamic voltage programming 1210.2007.02.1.2 23 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737- 4600 fax (408) 737- 4611 ? advanced analogic technologies, inc. analogictech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an analogictech product. 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 specifications 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 being relied on is current and complete. all products are sold sub- ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, 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 analogictech?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 parameters of each device is not necessarily performed. analogictech and the analogictech logo are trademarks of advanced analogic technologies incorporated. all other brand and product names appearing in this document are regis- tered trademarks or trademarks of their respective holders.

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