View AME5252_8374733.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

ame 1 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter l high efficiency: up to 96% l internal soft start l 1.5mhz constant frequency operation l high switch current: 1a on each channel l no schottky diodes required l low r dson internal switches: 0.35 w l current mode operation for excellent line and load transient response l short-circuit protected l low dropout operation: 100% duty cycle l ultralow shutdown current: i q <1 m a l output voltages from 5v down to 0.6v l power-on reset output l externally synchronizable oscillator l all ame ? s lead free products meet rohs standards the AME5252 is a dual, constant frequency, synchro- nous step down dc/dc converter. intended for low power applications, it operates from 2.5v to 5.5v input voltage range and has a constant 1.5mhz switching frequency, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. each output voltage is adjustable from 0.6v to 5v. internal synchronous 0.35 w , 1a power switches provide high efficiency without the need for ex- ternal schottky diodes. to further maximize battery life, the p-channel mosfets are turned on continuously in dropout (100% duty cycle). in shutdown model, the device draws <1 m a. n general description n features n applications s l pdas/palmtop pcs l digital cameras l cellular phones l portable media players l pc cards l wireless and dsl modems n typical application figure 1. 2.5v/1.8v at 600ma step-down regulators sw 1 vfb 1 gnd / pgnd in en 2 en 1 sw 2 vfb 2 porb sync c in 10 m f reset c out 1 10 m f r 2 887 k w r 1 442 k w r 3 280 k w r 4 887 k w cf 1 22 pf cf 2 22 pf r 5 100 k w l 2 2 . 2 m h v in 2 . 8 v ~ 5 . 5 v v out 1 = 1 . 8 v v out 2 = 2 . 5 v ame 5252 l 1 2 . 2 m h c out 2 10 m f
ame 2 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n typical application figure 2. 1.8v/1.2v at 600ma step-down regulators figure 3. 2.5v/1.5v at 600ma step-down regulators sw 1 vfb 1 gnd / pgnd in en 2 en 1 sw 2 vfb 2 porb sync c in 10 m f reset c out 1 10 m f r 2 604 k w r 1 604 k w r 3 442 k w r 4 887 k w cf 1 22 pf cf 2 22 pf r 5 100 k w l 2 2 . 2 m h v in 2 . 5 v ~ 5 . 5 v v out 1 = 1 . 2 v v out 2 = 1 . 8 v ame 5252 l 1 2 . 2 m h c out 2 10 m f sw 1 vfb 1 gnd / pgnd in en 2 en 1 sw 2 vfb 2 porb sync c in 10 m f reset c out 1 10 m f r 2 475 k w r 1 316 k w r 3 316 k w r 4 1 m w cf 1 22 pf cf 2 22 pf r 5 100 k w l 2 2 . 2 m h v in 2 . 8 v ~ 5 . 5 v v out 1 = 1 . 5 v v out 2 = 2 . 5 v ame 5252 l 1 2 . 2 m h c out 2 10 m f
ame 3 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n typical application figure 4. 3.3v/1.8v at 600ma step-down regulators sw 1 vfb 1 gnd / pgnd in en 2 en 1 sw 2 vfb 2 porb sync c in 10 m f c out 2 10 m f reset c out 1 10 m f r 2 887 k w r 1 442 k w r 3 196 k w r 4 887 k w cf 1 22 pf cf 2 22 pf r 5 100 k w l 2 2 . 2 m h v in 2 . 8 v ~ 5 . 5 v v out 1 = 1 . 8 v v out 2 = 3 . 3 v ame 5252 l 1 2 . 2 m h d 1 m 1
ame 4 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n function diagram + - + - uvdet ovdet switching logic and blanking circuit + - + - + - anti shoot - thru porb counter osc 0 . 6 v vref 0 . 6 v 0 . 65 v pgnd sw 1 vfb 1 sync en 2 en 1 vin porb sw 2 vfb 2 in regulator 2 0 . 55 v 1 6 2 9 10 clamp slope comp 3 8 7 4 11 ircmp ? p _ ch n _ ch 5 gnd
ame 5 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n pin configuration dfn-10b (3mmx3mmx0.75mm) top view AME5252-avbxxx 1. vfb1 2. en1 3. in 4. sw1 5. gnd 6. sync die attach: conductive epoxy 7. sw2 8. porb 9. en2 10. vfb2 11. *pgnd note: * the area enclosed by dashed line represents exposed pad (pin11) and must be connected to gnd. n pin description pin number pin name pin description 1 vfb1 regulator 1 output feedback. receives the feedback voltage from the external resistive divider across the output. nominal voltage for this pin is 0.6v. 2 en1 regulator 1 enable. forcing this pin to v in enables regulator 1, while forcing it to gnd caused regulator 1 to shutdown. 3 in main power supply. must be closely decoupled to gnd. 4 sw1 regulator 1 switch node connection to the inductor. this pin swings from v in to gnd. 5 gnd main ground. connect to the (-) terminal of c out , and (-) terminal of c in . 6 sync the oscillation frequency can be syncronized to an external oscillator applied to this pin and pulse skipping mode is automatically selected. do not float this pin. 7 sw2 regulator 2 switch node connection to the inductor. this pin swings from v in to gnd. 8 porb power-on reset. this common-drain logic output is pulled to gnd when the output voltage is not within 8.5% of regulation and goes high after 175ms when both channels are within regulation. 9 en2 requlator 2 enable. output feedback. forcing this pin to v in enables regulator 2, while forcing it to gnd causes regulator 2 to shut down. 10 vfb2 regulator 2 output feedback reveives the feedback voltage from the external resistive divider across the output nominal voltage for this pin is 0.6v. 11 pgnd must be connected to gnd. 4 1 2 3 ame 5252 5 7 10 9 8 6
ame 6 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n ordering information AME5252 - x x x xxx pin configuration & special feature package type number of pins output voltage a 1. vfb1 v: dfn b: 10 adj: adjustable (dfn-10b) 2. en1 3. in 4. sw1 5. gnd 6. sync 7. sw2 8. porb 9. en2 10.vfb2 11.pgnd pin configuration & special feature package type number of pins output voltage
ame 7 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n absolute maximum ratings n recommended operating conditions caution: stress above the listed absolute maximum rating may cause permanent damage to the device. * hbm b: 2000v ~ 3999v parameter symbol rating unit ambient temperature range t a -40 to +85 o c junction temperature range t j -40 to +125 o c storage temperature range t stg -65 to +150 o c n available options note: 1. the first 2 places represent product code. it is assigned by ame such as bm. 2. y is year code and is the last number of a year. such as the year code of 2008 is 8. 3. a bar on top of first letter represents green part such as a5252. 4. the last 3 places mxx represent marking code. it contains m as date code in "month", xx as ln code and that is for ame internal use only. please refer to date code rule section for detail information. 5. please consult ame sales office or authorized rep./distributor for the availability of output voltage and package type. parameter symbol maximum unit input supply voltage in -0.3v to 6v v fb1 , v fb2 , en1,en2 voltage v en , v fb -0.3v to v in +0.3 sync ,sw1, sw2 voltage v sw -0.3v to v in +0.3 esd classification v b* part number marking output voltage package operating ambient temperature range AME5252-avbadj a5252 bmymxx adj dfn-10b -40 o c to +85 o c
ame 8 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n thermal information * measure q jc on backside center of exposed pad. ** mil-std-202g 210f parameter package die attach symbol maximum unit thermal resistance* (junction to case) q jc 17 thermal resistance (junction to ambient) q ja 125 internal power dissipation p d 800 mw 350 o c solder iron (10 sec)** dfn-10b conductive epoxy o c / w
ame 9 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n electrical specifications v in =3.6v, en =v in , t a = 25 o c, c in =10 m f, i load =0a, unless otherwise noted. parameter symbol min typ max units input voltage v in 2.5 5.5 v fb pin input current i fb 30 na 0.588 0.6 0.612 v 0.585 0.6 0.615 v reference voltage line regulation reg line,fb 0.3 0.5 %/v output voltage load regulation reg load 0.05 % quiescent current i q 600 800 m a shutdown current i shdn 0.1 1 m a switching frequency f osc 1.2 1.5 1.8 mhz top switch on-resistance bottom switch on-resistance switch current limit i cl 0.95 1.2 a switch leakage current i sw 0.1 1 m a 8.5 % -8.5 % power-on reset on-resistance 100 200 w power-on reset delay 175 ms en input threshold (high) (enable the device) 1.5 v en input threshold (low) (shutdown) 0.3 v thermal shutdown temperature otp 160 thermal shutdown hysteresis oth 20 en threshold porb r dson 0.35 v fbx ramping up, sync=0v v in =3v, v out =1.2v v in =3.6v, v en =0v, v sw =0v or 3.6v v fb 0.55 w -40 o c ?? t a ?? +85 o c v fbx ramping down, sync=0v power-on reset threshold test condition en=0v v fb1 =v fb2 =0.5v (switching) feedback trip point shutdown, temperature increasing o c restore, temperature decreasing
ame 10 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n detailed description the AME5252 uses a constant frequency, current mode architecture. the operating frequency is set at 1.5mhz and can be synchronized to an external oscillator. both channels share the same clock and run in-phase. the output voltage is set by an external divider returned to the v fb pins. an error amplifier compares the divided output voltage with a reference voltage of 0.6v and adjusts the peak inductor current accordingly. overvoltage and undervoltage comparators will pull the porb output low if the output voltage is not within 8.5%. the porb output will go high after 262,144 clock cycles (about 175ms) of achieving regulation. main control loop during normal operation, the top power switch (p-chan- nel mosfet) is turned on at the beginning of a clock cycle when the v fb voltage is below the reference voltage. the current into the inductor and the load increases until the current limit is reached. the switch turns off and en- ergy stored in the inductor flows through the bottom switch (n-channel mosfet) into the load until the next clock cycle. the peak inductor current is controlled by the internally compensated comp voltage, which is the output of the error amplifier. this amplifier compares the v fb pin to the 0.6v reference. when the load current increases, the v fb voltage decreases slightly below the reference. this de- crease causes the error amplifier to increase the comp voltage until the average inductor current matches the new load current. the main control loop is shut down by pull- ing the en pin to ground. dropout operation when the input supply voltage decreases toward the output voltage, the duty cycle increases to 100% which is the dropout condition. in dropout, the p-channel mosfet switch is turned on continuously with the output voltage being equal to the input voltage minus the voltage drops across the internal p-channel mosfet and the inductor. an important design consideration is that the r dson of the p-channel switch increases with decreasing input sup- ply voltage (see typical performance characteristics). therefore, the user should calculate the power dissipa- tion when the AME5252 is used at 100% duty cycle with low input voltage. c short-circuit protection when the output is shorted to ground, the frequency of the oscillator is reduced to about 210khz, 1/7 the nominal frequency. this frequency foldback ensures that the in- ductor current has more time to decay, thereby preventing runaway. the oscillator's frequency will progressively in- crease to 1.5mhz when v fb or v out rises above 0v. n application information for most applications, the value of the inductor will fall in the range of 1 m h to 4.7 m h. its value is chosen based on the desired ripple current. large value inductors lower ripple current and small value inductors result in higher ripple currents. higher v in or v out also increases the ripple cur- rent as shown in equation 1. a reasonable starting point for setting ripple current is il = 240ma (40% of 600ma). ) 1 ( 1 l v in v out l f i - = d v out the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. thus, a 720ma rated inductor should be enough for most applications (600ma+ 120ma). for better efficiency, choose a low dc-resistance inductor. inductor selection
ame 11 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter inductor core selection once the value for l is known, the type of inductor must be selected. high efficiency converters generally cannot afford the core loss found in low cost powdered iron cores, forcing the use of more expensive ferrite or mollypermalloy cores. actual core loss is independent of core size for a fixed inductor value but it is very depen- dent on the inductance selected. as the inductance in- creases, core losses decrease. unfortunately, increased inductance requires more turns of wire and therefore cop- per losses will increase. ferrite designs have very low core losses and are preferred at high switching frequen- cies, so design goals can concentrate on copper loss and preventing saturation. ferrite core material saturates "hard", which means that inductance collapses abruptly when the peak design current is exceeded. this result in an abrupt increase in inductor ripple current and conse- quent output voltage ripple. do not allow the core to satu- rate! different core materials and shapes will change the size/current and price/current relationship of an inductor. toroid or shielded pot cores in ferrite or permalloy mate- rials are small and don't radiate energy but generally cost more than powdered iron core inductors with similar char- acteristics. the choice of which style inductor to use mainly depends on the price vs. size requirements and any radiated field/emi requirements. c in and c out selection the input capacitance, cin, is needed to filter the trap- ezoidal current at the source of the top mosfet. to pre- vent large ripple voltage, a low esr input capacitor sized for the maximum rms current should be used.rms cur- rent is given by : this formula has a maximum at v in = 2v out , where i rms = i out /2. this simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. note that ripple current ratings from capacitor manufacturers are often based on only 2000 hours of life which makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher tem- perature than required. several capacitors may also be paralleled to meet size or height requirements in the design. the selection of cout is determined by the effective series resistance (esr) that is required to minimize voltage ripple and load step transients, as well as the amount of bulk capaci- tance that is necessary to ensure that the control loop is stable. loop stability can be checked by viewing the load transient response as described in a later section. the output ripple, v out , is determined by : 1 ) ( - = v out v in v in v out max i out i rms ? ? + d d c out f esr i l v out 8 1 the output ripple is highest at maximum input voltage since il increases with input voltage. multiple capacitors placed in parallel may be needed to meet the esr and rms current handling requirements. dry tantalum, spe- cial polymer, aluminum electrolytic and ceramic capaci- tors are all available in surface mount packages. special polymer capacitors offer very low esr but have lower capacitance density than other types. tantalum capaci- tors have the highest capacitance density but it is impor- tant to only use types that have been surge tested for use in switching power supplies. aluminum electrolytic capacitors have significantly higher esr but can be used in cost-sensitive applications provided that consideration is given to ripple current ratings and long term reliability. ceramic capacitors have excellent low esr characteris- tics but can have a high voltage coefficient and audible piezoelectric effects. the high q of ceramic capacitors with trace inductance can also lead to significant ringing using ceramic input and output capacitors higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. their high ripple current, high voltage rating and low esr make them ideal for switching regulator applications. however, care must be taken when these capacitors are used at the input and output. when a ceramic capacitor is used at the input and the power is supplied by a wall adapter through long wires, a load step at the output can induce ringing at the input, v in . at best, this ringing can couple to the output and be mistaken as loop instability. at worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at v in large enough to damage the part.
ame 12 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter thermal considerations in most applications the AME5252 does not dissipate much heat due to its high efficiency. but, in applications where the AME5252 is running at high ambient tempera- ture with low supply voltage and high duty cycles, such as in dropout, the heat dissipated may exceed the maxi- mum junction temperature of the part. if the junction tem- perature reaches approximately 160 o c, both power switches will be turned off and the sw node will become high impedance. to avoid the AME5252 from exceeding the maximum junction temperature, the user will need to do some thermal analysis. the goal of the thermal analy- sis is to determine whether the power dissipated exceeds the maximum junction temperature of the part. the tem- perature rise is given by: where pd is the power dissipated by the regulator and q ja is the thermal resistance from the junction of the die to the ambient temperature. ) )( ( pd t r q ja =
ame 13 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter start-up form shutdown pluse skipping mode v sw 5 v / div v out 10 mv / div i sw 200 ma / div v in = 3 . 6 v v out = 1 . 8 v i load = 50 ma 1 m s / div load step efficiency vs input voltage 50 55 60 65 70 75 80 85 90 95 100 2 3 4 5 6 e f f i c i e n c y ( % ) input voltage ( v ) i out = 100 ma i out = 10 ma i out = 600 ma oscillator frequency vs temperature 1 . 0 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 - 40 - 15 + 10 + 35 + 60 + 85 + 110 f r e q u e n c y ( m h z ) temperature ( o c ) oscillator frequency vs supply voltage 1 . 0 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 2 3 4 5 6 f r e q u e n c y ( m h z ) supply voltage ( v ) v out 200 mv / div i sw 500 mv / div i out 500 ma / div v in = 3 . 6 v v out = 1 . 8 v i load = 50 ma to 600 ma 20 m s / div en 5 v / div v out 1 v / div i l 500 ma / div v in = 3 . 6 v v out = 1 . 8 v i out = 800 ma 50 m s / div
ame 14 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter v fb vs temperature r ds(on) vs input voltage 0 . 20 0 . 25 0 . 30 0 . 35 0 . 40 0 . 45 0 . 50 0 . 55 0 . 60 0 . 65 1 2 3 4 5 6 7 r d s ( o n ) ( m w ) main switch synchronous switch input voltage ( v ) r ds(on) vs temperature efficiency vs load current efficiency vs load current efficiency vs load current v f b ( v ) temperature ( o c ) 0 . 584 0 . 588 0 . 592 0 . 596 0 . 600 0 . 604 0 . 608 0 . 612 0 . 616 - 40 - 15 + 10 + 35 + 60 + 85 + 110 v in = 3 . 6 v 0 . 20 0 . 25 0 . 30 0 . 35 0 . 40 0 . 45 0 . 50 0 . 55 0 . 60 0 . 65 0 . 70 - 50 - 25 0 + 25 + 50 + 75 + 100 + 125 r d s ( o n ) ( m w ) temperature ( o c ) v in = 4 . 2 v v in = 3 . 6 v v in = 2 . 7 v main switch synchronous switch 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 e f f i c i e n c y ( % ) i out ( ma ) v in = 2 . 7 v v in = 3 . 6 v v in = 4 . 2 v v out = 2 . 5 v i out ( ma ) 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 e f f i c i e n c y ( % ) v in = 2 . 7 v v in = 3 . 6 v v in = 4 . 2 v v out = 1 . 8 v 20 30 40 50 60 70 80 90 100 1 10 100 1000 i out ( ma ) e f f i c i e n c y ( % ) v in = 2 . 7 v v in = 4 . 2 v v in = 3 . 6 v v out = 1 . 2 v
ame 15 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter efficiency vs load current 20 30 40 50 60 70 80 90 100 1 10 100 1000 v in = 2 . 7 v v in = 4 . 2 v v in = 3 . 6 v v out = 1 . 5 v i out ( ma ) e f f i c i e n c y ( % ) current limit vs v in current limit vs temperature current limit vs temperature 0 . 7 0 . 8 0 . 9 1 . 0 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 5 2 . 8 3 . 1 3 . 4 3 . 7 4 . 0 4 . 3 4 . 6 4 . 9 5 . 2 5 . 5 v in ( v ) c u r r e n t l i m i t ( a ) channel 1 channel 2 v out 1 = 1 . 2 v v out 2 = 1 . 2 v 0 . 70 0 . 80 0 . 90 1 . 00 1 . 10 1 . 20 1 . 30 1 . 40 1 . 50 1 . 60 1 . 70 1 . 80 1 . 90 2 . 00 2 . 10 - 40 - 25 - 10 + 5 + 20 + 35 + 50 + 65 + 80 + 95 + 110 + 125 c u r r e n t l i m i t ( a ) temperature ( o c ) v in = 3 . 3 v v out 1 = 1 . 2 v v out 2 = 1 . 2 v channel 1 channel 2 0 . 70 0 . 80 0 . 90 1 . 00 1 . 10 1 . 20 1 . 30 1 . 40 1 . 50 1 . 60 1 . 70 1 . 80 1 . 90 2 . 00 2 . 10 - 40 - 25 - 10 + 5 + 20 + 35 + 50 + 65 + 80 + 95 + 110 + 125 c u r r e n t l i m i t ( a ) temperature ( o c ) channel 1 channel 2 v in = 3 . 6 v v out 1 = 1 . 2 v v out 2 = 1 . 2 v 1 . 774 1 . 784 1 . 794 1 . 804 1 . 814 1 . 824 1 . 834 1 . 844 1 10 100 1000 i out ( ma ) e f f i c i e n c y ( % ) output voltage vs load current current limit vs temperature 0 . 70 0 . 80 0 . 90 1 . 00 1 . 10 1 . 20 1 . 30 1 . 40 1 . 50 1 . 60 1 . 70 1 . 80 1 . 90 2 . 00 2 . 10 - 40 - 25 - 10 + 5 + 20 + 35 + 50 + 65 + 80 + 95 + 110 + 125 c u r r e n t l i m i t ( a ) temperature ( o c ) channel 1 channel 2 v in = 5 . 0 v v out 1 = 1 . 2 v v out 2 = 1 . 2 v
ame 16 AME5252 rev. c.01 dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n tape and reel dimension n date code rule 1: january 7: july 2: february 8: august 3: march 9: september 4: april a: october 5: may b: november 6: june c: december month code w p pin 1 a m e a m e dfn-10b (3mmx3mmx0.75mm) carrier tape, number of components per reel and reel size package carrier width (w) pitch (p) part per full reel reel size dfn-10b (3x3x0.75mm) 12.00.1 mm 4.00.1 mm 3000pcs 3301 mm
ame 17 AME5252 rev.c.01 c dual synchronous, 600ma, 1.5mhz step-down dc/dc converter n package dimension dfn-10b (3mmx3mmx0.75mm) min max min max a 0.700 0.800 0.028 0.031 d 2.900 3.100 0.114 0.122 e 2.900 3.100 0.114 0.122 e 0.450 0.550 0.018 0.022 d1 2.300 2.500 0.091 0.098 e1 1.600 1.800 0.063 0.071 b 0.180 0.300 0.007 0.012 l 0.300 0.500 0.012 0.020 g 0.153 0.253 0.006 0.010 g1 0.000 0.050 0.000 0.002 symbols millimeters inches top view bottom view rear view e d e g g 1 b l e 1 d 1 pin 1 identification a
life support policy: these products of ame, inc. are not authorized for use as critical components in life-support devices or systems, without the express written approval of the president of ame, inc. ame, inc. reserves the right to make changes in the circuitry and specifications of its devices and advises its customers to obtain the latest version of relevant information. ? ame, inc. , september 2009 document: 1045-ds5252-c.01 corporate headquarter ame, inc. 2f, 302 rui-guang road, nei-hu district taipei 114, taiwan. tel: 886 2 2627-8687 fax: 886 2 2659-2989 www.ame.com.tw e-mail: sales@ame.com.tw

▲Up To Search▲

Price & Availability of AME5252

	To Download AME5252 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .