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iru3037 / iru3037a 1 rev. 2.7 08/22/02 www.irf.com typical application description the iru3037 controller ic is designed to provide a low cost synchronous buck regulator for on-board dc to dc converter applications. with the migration of today?s asic products requiring low supply voltages such as 1.8v and lower, together with currents in excess of 3a, traditional linear regulators are simply too lossy to be used when input supply is 5v or even in some cases with 3.3v input supply. the iru3037 together with dual n-channel mosfets such as irf7313, provide a low cost solution for such applications. this device features an internal 200khz oscillator (400khz for "a" version), under-volt- age lockout for both vcc and vc supplies, an external programmable soft-start function as well as output un- der-voltage detection that latches off the device when an output short is detected. synchronous controller in 8-pin package operating with single 5v or 12v supply voltage internal 200khz oscillator (400khz for iru3037a) soft-start function fixed frequency voltage mode 500ma peak output drive capability protects the output when control fet is shorted package order information features 8-pin synchronous pwm controller applications ddr memory source sink vtt application low cost on-board dc to dc such as 5v to 3.3v, 2.5v or 1.8v graphic card hard disk drive t a ( c) device package frequency 0 to 70 iru3037cf 8-pin plastic tssop (f) 200khz 0 to 70 iru3037cs 8-pin plastic soic nb (s) 200khz 0 to 70 iru3037acf 8-pin plastic tssop (f) 400khz 0 to 70 iru3037acs 8-pin plastic soic nb (s) 400khz data sheet no. pd94173 figure 1 - typical application of iru3037 or iru3037a. iru3037 u1 vcc vc hdrv ldrv fb gnd comp ss c3 0.1uf c4 1uf c8 0.1uf c9 2200pf r4 24k q1 1/2 of irf7313 q2 1/2 of irf7313 r5 1.24k, 1% r3 249, 1% l2 d05022p-562, 5.6uh, 5.3a l1 1uh c2 10tpb100m, 100uf, 55m v c1 47uf 1.5v/5a c7 2x 6tpc150m, 150uf, 40m v 12v 5v
2 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com electrical specifications unless otherwise specified, these specifications apply over vcc=5v, vc=12v and t a =0 to 70c. typical values refer to t a =25c. low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature. absolute maximum ratings vcc supply voltage .................................................. 25v vc supply voltage ...................................................... 30v (not rated for inductive load) storage temperature range ...................................... -65c to 150c operating junction temperature range ..................... 0c to 125c package information 8-pin plastic tssop (f) 8-pin plastic soic (s) parameter sym test condition min typ max units fb vcc ldrv gnd hdrv vc comp ss 4 3 2 1 5 6 7 8 reference voltage fb voltage fb voltage line regulation uvlo uvlo threshold - vcc uvlo hysteresis - vcc uvlo threshold - vc uvlo hysteresis - vc uvlo threshold - fb uvlo hysteresis - fb supply current vcc dynamic supply current vc dynamic supply current vcc static supply current vc static supply current soft-start section charge current iru3037 iru3037a 5 iru3037 / iru3037a 3 rev. 2.7 08/22/02 www.irf.com parameter sym test condition min typ max units pin descriptions this pin is connected directly to the output of the switching regulator via resistor divider to provide feedback to the error amplifier. this pin provides biasing for the internal blocks of the ic as well as power for the low side driver. a minimum of 1 m f, high frequency capacitor must be connected from this pin to ground to provide peak drive current capability. output driver for the synchronous power mosfet. this pin serves as the ground pin and must be connected directly to the ground plane. a high frequency capacitor (0.1 to 1 m f) must be connected from v5 and v12 pins to this pin for noise free operation. output driver for the high side power mosfet. connect a diode, such as bat54 or 1n4148, from this pin to ground for the application when the inductor current goes negative (source/ sink), soft-start at no load and for the fast load transient from full load to no load. this pin is connected to a voltage that must be at least 4v higher than the bus voltage of the switcher (assuming 5v threshold mosfet) and powers the high side output driver. a minimum of 1 m f, high frequency capacitor must be connected from this pin to ground to provide peak drive current capability. compensation pin of the error amplifier. an external resistor and capacitor network is typically connected from this pin to ground to provide loop compensation. this pin provides soft-start for the switching regulator. an internal current source charges an external capacitor that is connected from this pin to ground which ramps up the output of the switching regulator, preventing it from overshooting as well as limiting the input current. the converter can be shutdown by pulling this pin below 0.5v. error amp fb voltage input bias current fb voltage input bias current transconductance oscillator frequency ramp-amplitude voltage output drivers rise time fall time dead band time max duty cycle min duty cycle ss=3v, fb=1v ss=0v, fb=1v iru3037 iru3037a c l =1500pf c l =1500pf fb=1v, freq=200khz fb=1.5v 450 180 360 1.225 50 85 0 -0.1 -64 600 200 400 1.25 50 50 150 90 0 750 220 440 1.275 100 100 250 95 m a m a m mho khz v ns ns ns % % pin# pin symbol pin description 1 2 3 4 5 6 7 8 fb vcc ldrv gnd hdrv vc comp ss i fb1 i fb2 g m freq v ramp t r t f t db t on t off
4 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com block diagram figure 2 - simplified block diagram of the iru3037. theory of operation introduction the iru3037 is a fixed frequency, voltage mode syn- chronous controller and consists of a precision refer- ence voltage, an error amplifier, an internal oscillator, a pwm comparator, 0.5a peak gate driver, soft-start and shutdown circuits (see block diagram). the output voltage of the synchronous converter is set and controlled by the output of the error amplifier; this is the amplified error signal from the sensed output voltage and the reference voltage. this voltage is compared to a fixed frequency linear sawtooth ramp and generates fixed frequency pulses of variable duty-cycle, which drives the two n-channel ex- ternal mosfets.the timing of the ic is provided through an internal oscillator circuit which uses on-chip capaci- tor to set the oscillation frequency to 200 khz (400 khz for ?a? version). soft-start the iru3037 has a programmable soft-start to control the output voltage rise and limit the current surge at the start-up. to ensure correct start-up, the soft-start se- quence initiates when the vc and vcc rise above their threshold (3.3v and 4.2v respectively) and generates the power on reset (por) signal. soft-start function operates by sourcing an internal current to charge an external capacitor to about 3v. initially, the soft-start func- tion clamps the e/a?s output of the pwm converter. as the charging voltage of the external capacitor ramps up, the pwm signals increase from zero to the point the feedback loop takes control. short-circuit protection the outputs are protected against the short-circuit. the iru3037 protects the circuit for shorted output by sens- ing the output voltage (through the external resistor di- vider). the iru3037 shuts down the pwm signals, when the output voltage drops below 0.6v (0.4v for iru3037a). the iru3037 also protects the output from over-voltaging when the control fet is shorted. this is done by turning on the sync fet with the maximum duty cycle. under-voltage lockout the under-voltage lockout circuit assures that the mosfet driver outputs remain in the off state whenever the supply voltage drops below set parameters. lockout occurs if vc and vcc fall below 3.3v and 4.2v respec- tively. normal operation resumes once vc and vcc rise above the set values. 20ua 64ua max por oscillator error amp ct error comp reset dom por 0.5v fblo comp 3 vc hdrv vcc ldrv gnd vcc 4.0v vc 3.5v 0.2v 0.2v bias generator 3v 1.25v por 8 ss fb 1 comp 7 25k 25k 1.25v 3v 2 6 5 r s q 4
iru3037 / iru3037a 5 rev. 2.7 08/22/02 www.irf.com figure 3 - typical application of the iru3037 for programming the output voltage. application information design example: the following example is a typical application for iru3037, the schematic is figure 18 on page 14. output voltage programming output voltage is programmed by reference voltage and external voltage divider. the fb pin is the inverting input of the error amplifier, which is internally referenced to 1.25v (0.8v for iru3037a). the divider is ratioed to pro- vide 1.25v at the fb pin when the output is at its desired value. the output voltage is defined by using the follow- ing equation: when an external resistor divider is connected to the output as shown in figure 3. equation (1) can be rewritten as: choose r 5 = 1k v this will result to r 6 = 1.65k v if the high value feedback resistors are used, the input bias current of the fb pin could cause a slight increase in output voltage. the output voltage set point can be more accurate by using precision resistor. soft-start programming the soft-start timing can be programmed by selecting the soft start capacitance value. the start up time of the converter can be calculated by using: where: c ss is the soft-start capacitor ( m f) for a start-up time of 7.5ms, the soft-start capacitor will be 0.1 m f. choose a ceramic capacitor at 0.1 m f. shutdown the converter can be shutdown by pulling the soft-start pin below 0.5v. the control mosfet turns off and the synchronous mosfet turns on during shutdown. boost supply vc to drive the high-side switch it is necessary to supply a gate voltage at least 4v greater than the bus voltage. this is achieved by using a charge pump configuration as shown in figure 18. the capacitor is charged up to approximately twice the bus voltage. a capacitor in the range of 0.1 m f to 1 m f is generally adequate for most applications. in application, when a separate voltage source is available the boost circuit can be avoided as shown in figure 1. input capacitor selection the input filter capacitor should be based on how much ripple the supply can tolerate on the dc input line. the larger capacitor, the less ripple expected but consider should be taken for the higher surge current during the power-up. the iru3037 provides the soft-start function which controls and limits the current surge. the value of the input capacitor can be calculated by the following formula: where: c in is the input capacitance ( m f) i in is the input current (a) d t is the turn on time of the high-side switch ( m s) d v is the allowable peak to peak voltage ripple (v) fb iru3037 v out r 5 r 6 t start = 75 3 css (ms) ---(2) v in = 5v v out = 3.3v i out = 4a d v out = 100mv f s = 200khz r 6 = r 5 3 - 1 v out v ref ( ) v out = v ref 3 1 + ---(1) r 6 r 5 ( ) c in = ---(3) i in 3 d t d v
6 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com assuming the following: by using equation (3), c in = 193.3 m f for higher efficiency, low esr capacitor is recommended. choose two 100 m f capacitors. the sanyo tpb series poscap capacitor 100 m f, 10v with 55m v esr is a good choice. output capacitor selection the criteria to select the output capacitor is normally based on the value of the effective series resistance (esr). in general, the output capacitor must have low enough esr to meet output ripple and load transient requirements, yet have high enough esr to satisfy sta- bility requirements. the esr of the output capacitor is calculated by the following relationship: the sanyo tpc series, poscap capacitor is a good choice. the 6tpc150m 150 m f, 6.3v has an esr 40m v . selecting two of these capacitors in parallel, results to an esr of @ 20m v which achieves our low esr goal. the capacitor value must be high enough to absorb the inductor's ripple current. the larger the value of capaci- tor, the lower will be the output ripple voltage. inductor selection the inductor is selected based on output power, operat- ing frequency and efficiency requirements. low inductor value causes large ripple current, resulting in the smaller size, but poor efficiency and high output noise. gener- ally, the selection of inductor value can be reduced to desired maximum ripple current in the inductor ( d i). the optimum point is usually found between 20% and 50% ripple of the output current. for the buck converter, the inductor value for desired operating ripple current can be determined using the fol- lowing relation: if d i = 20%(i o ), then the output inductor will be: the toko d124c series provides a range of inductors in different values, low profile suitable for large currents, 10 m h, 4.2a is a good choice for this application. this will result to a ripple approximately 14% of output cur- rent. power mosfet selection the iru3037 uses two n-channel mosfets. the se- lections criteria to meet power transfer requirements is based on maximum drain-source voltage (v dss ), gate- source drive voltage (v gs ), maximum output current, on- resistance r ds(on) and thermal management. the mosfet must have a maximum operating voltage (v dss ) exceeding the maximum input voltage (v in ). the gate drive requirement is almost the same for both mosfets. logic-level transistor can be used and cau- tion should be taken with devices at very low v gs to pre- vent undesired turn-on of the complementary mosfet, which results a shoot-through current. the total power dissipation for mosfets includes con- duction and switching losses. for the buck converter the average inductor current is equal to the dc load cur- rent. the conduction loss is defined as: the r ds(on) temperature dependency should be consid- ered for the worst case operation. this is typically given in the mosfet data sheet. ensure that the conduction losses and switching losses do not exceed the package ratings or violate the overall thermal budget. l = 7 m h where: v in = maximum input voltage v out = output voltage d i = inductor ripple current f s = switching frequency d t = turn on time d = duty cycle 2 2 p cond (upper switch) = i load 3 r ds(on) 3 d 3 q p cond (lower switch) = i load 3 r ds(on) 3 (1 - d) 3 q q = r ds(on) temperature dependency d t = d 3 y y d t = 3.3 m s 1 f s i in = y y i in = 2.93a d v = 1%(v in ), efficiency( h ) = 90% v o 3 i o h 3 v in where: d v o = output voltage ripple d i o = output current d v o =100mv and d i o =4a results to esr=25m v esr [ ---(4) d v o d i o v in - v out = l 3 ; d t = d 3 ; d = d i d t 1 f s v in v out l = (v in - v out ) 3 ---(5) v out v in 3d i 3 f s
iru3037 / iru3037a 7 rev. 2.7 08/22/02 www.irf.com for this design, irf7301 is a good choice. the device provides low on-resistance in a compact soic 8-pin package. the irf7301 has the following data: the total conduction losses will be: the switching loss is more difficult to calculate, even though the switching transition is well understood. the reason is the effect of the parasitic components and switching times during the switching procedures such as turn-on / turnoff delays and rise and fall times. with a linear approximation, the total switching loss can be ex- pressed as: the switching time waveform is shown in figure 4. figure 4 - switching time waveforms. from irf7301 data sheet we obtain: these values are taken under a certain condition test. for more detail please refer to the irf7301 data sheet. by using equation (6), we can calculate the switching losses. feedback compensation the iru3037 is a voltage mode controller; the control loop is a single voltage feedback path including error amplifier and error comparator. to achieve fast transient response and accurate output regulation, a compensa- tion circuit is necessary. the goal of the compensation network is to provide a closed loop transfer function with the highest 0db crossing frequency and adequate phase margin (greater than 45 8 ). the output lc filter introduces a double pole, ?40db/ decade gain slope above its corner resonant frequency, and a total phase lag of 180 8 (see figure 5). the reso- nant frequency of the lc filter expressed as follows: figure 5 shows gain and phase of the lc filter. since we already have 180 8 phase shift just from the output filter, the system risks being unstable. figure 5 - gain and phase of lc filter. the iru3037?s error amplifier is a differential-input transconductance amplifier. the output is available for dc gain control or ac phase compensation. the e/a can be compensated with or without the use of local feedback. when operated without local feedback the transconductance properties of the e/a become evi- dent and can be used to cancel one of the output filter poles. this will be accomplished with a series rc circuit from comp pin to ground as shown in figure 6. v dss = 20v i d = 5.2a r ds(on) = 0.05 v where: v ds(off) = drain to source voltage at off time t r = rise time t f = fall time t = switching period i load = load current t r = 42ns t f = 51ns p sw = 0.186w p con(total) =p con (upper switch)+p con (lower switch) p con(total) = i load 3 r ds(on) 3 q 2 q = 1.5 according to the irf7301 data sheet for 150 8 c junction temperature p con(total) = 1.2w f lc = ---(7) 1 2 p3 l o 3 c o p sw = i load ---(6) t r + t f t v ds(off) 2 3 3 v ds v gs 10% 90% t d (on) t d (off) t r t f gain f lc 0db phase 0 8 f lc -180 8 frequency frequency -40db/decade
8 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com note that this method requires that the output capacitor should have enough esr to satisfy stability requirements. in general the output capacitor?s esr generates a zero typically at 5khz to 50khz which is essential for an acceptable phase margin. the esr zero of the output capacitor expressed as fol- lows: figure 6 - compensation network without local feedback and its asymptotic gain plot. the transfer function (ve / v out ) is given by: the (s) indicates that the transfer function varies as a function of frequency. this configuration introduces a gain and zero, expressed by: the gain is determined by the voltage divider and e/a's transconductance gain. first select the desired zero-crossover frequency (fo): use the following equation to calculate r 4 : where: v in = maximum input voltage v osc = oscillator ramp voltage fo = crossover frequency f esr = zero frequency of the output capacitor f lc = resonant frequency of the output filter r 5 and r 6 = resistor dividers for output voltage programming g m = error amplifier transconductance this results to r 4 =104.4k v . choose r 4 =105k v to cancel one of the lc filter poles, place the zero be- fore the lc filter resonant frequency pole: using equations (11) and (13) to calculate c 9 , we get: one more capacitor is sometimes added in parallel with c 9 and r 4 . this introduces one more pole which is mainly used to supress the switching noise. the additional pole is given by: the pole sets to one half of switching frequency which results in the capacitor c pole: for: v in = 5v v osc = 1.25v fo = 30khz f esr = 26.52khz f lc = 2.9khz r 5 = 1k r 6 = 1.65k g m = 600 m mho c 9 = 698pf choose c 9 = 680pf f p = 2 p 3 r 4 3 c 9 3 c pole c 9 + c pole 1 v out v ref r 5 r 6 r 4 c 9 ve e/a f z h(s) db frequency gain(db) fb comp f esr = ---(8) 1 2 p 3 esr 3 co f z @ 75%f lc f z @ 0.75 3 ---(13) 1 2 p l o 3 c o for: lo = 10 m h co = 300 m f f z = 2.17khz r 4 = 86.6k v fo > f esr and f o [ (1/5 ~ 1/10) 3 f s h(s) = g m 3 3 ---(9) ( ) r 5 r 6 + r 5 1 + sr 4 c 9 sc 9 f z = ---(11) 1 2 p3 r 4 3 c 9 |h(s)| = g m 3 3 r 4 ---(10) r 5 r 6 3 r 5 r 4 = ---(12) v osc v in fo 3 f esr f lc 2 r 5 + r 6 r 5 1 g m 3 3 3 c pole = p3 r 4 3 f s - 1 for f p << f s 2 1 c 9 @ 1 p3 r 4 3 f s
iru3037 / iru3037a 9 rev. 2.7 08/22/02 www.irf.com for a general solution for unconditionally stability for any type of output capacitors, in a wide range of esr values we should implement local feedback with a compensa- tion network. the typically used compensation network for voltage-mode controller is shown in figure 7. figure 7 - compensation network with local feedback and its asymptotic gain plot. in such configuration, the transfer function is given by: the error amplifier gain is independent of the transcon- ductance under the following condition: by replacing z in and z f according to figure 7, the trans- former function can be expressed as: as known, transconductance amplifier has high imped- ance (current source) output, therefore, consider should be taken when loading the e/a output. it may exceed its source/sink output current capability, so that the ampli- fier will not be able to swing its output voltage over the necessary range. the compensation network has three poles and two ze- ros and they are expressed as follows: cross over frequency: the stability requirement will be satisfied by placing the poles and zeros of the compensation network according to following design rules. the consideration has been taken to satisfy condition (14) regarding transconduc- tance error amplifier. 1) select the crossover frequency: fo < f esr and fo [ (1/10 ~ 1/6) 3 f s 2) select r 7 , so that r 7 >> 3) place first zero before lc?s resonant frequency pole. f z1 @ 75% f lc 4) place third pole at the half of the switching frequency. c 12 > 50pf if not, change r 7 selection. 5) place r 7 in (15) and calculate c 10 : 2 g m 1 - g m z f 1 + g m z in v e v out = where: v in = maximum input voltage v osc = oscillator ramp voltage lo = output inductor co = total output capacitors c 11 = 1 2 p 3 f z1 3 r 7 c 12 = 1 2 p 3 r 7 3 f p3 f p3 = f s 2 c 10 [ 3 2 p 3 lo 3 fo 3 co r 7 v osc v in f p1 = 0 1 2 p3 c 10 3 (r 6 + r 8 ) f z2 = @ 1 2 p3 c 10 3 r 6 f z1 = 1 2 p3 r 7 3 c 11 f p3 = @ 1 c 12 3 c 11 c 12 +c 11 2 p3 r 7 3 1 2 p3 r 7 3 c 12 f p2 = 1 2 p3 r 8 3 c 10 ( ) v out v ref r 5 r 6 r 8 c 10 c 12 c 11 r 7 ve f z 1 f z 2 f p 2 f p 3 e/a z f z in frequency gain(db) h(s) db fb comp g m z f >> 1 and g m z in >>1 ---(14) h(s)= 3 (1+sr 7 c 11 ) 3 [1+sc 10 (r 6 +r 8 )] 1 sr 6 (c 12 +c 11 ) 1+sr 7 3 (1+sr 8 c 10 ) [ ( )] c 12 3 c 11 c 12 +c 11 f o = r 7 3 c 10 3 3 ---(15) v in v osc 1 2 p3 lo 3 co
10 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com 6) place second pole at the esr zero. f p2 = f esr check if r 8 > if r 8 is too small, increase r 7 and start from step 2. 7) place second zero around the resonant frequency. f z2 = f lc 8) use equation (1) to calculate r 5 . these design rules will give a crossover frequency ap- proximately one-tenth of the switching frequency. the higher the band width, the potentially faster the load tran- sient speed. the gain margin will be large enough to provide high dc-regulation accuracy (typically -5db to - 12db). the phase margin should be greater than 45 8 for overall stability. ic quiescent power dissipation power dissipation for ic controller is a function of ap- plied voltage, gate driver loads and switching frequency. the ic's maximum power dissipation occurs when the ic operating with single 12v supply voltage (vcc=12v and vc @ 24v) at 400khz switching frequency and maxi- mum gate loads. figures 9 and 10 show voltage vs. current, when the gate drivers loaded with 470pf, 1150pf and 1540pf ca- pacitors. the ic's power dissipation results to an exces- sive temperature rise. this should be considered when using iru3037a for such application. layout consideration the layout is very important when designing high fre- quency switching converters. layout will affect noise pickup and can cause a good design to perform with less than expected results. start to place the power components, make all the con- nection in the top layer with wide, copper filled areas. the inductor, output capacitor and the mosfet should be close to each other as possible. this helps to reduce the emi radiated by the power traces due to the high switching currents through them. place input capacitor directly to the drain of the high-side mosfet, to reduce the esr replace the single input capacitor with two par- allel units. the feedback part of the system should be kept away from the inductor and other noise sources, and be placed close to the ic. in multilayer pcb use one layer as power ground plane and have a control cir- cuit ground (analog ground), to which all signals are ref- erenced. the goal is to localize the high current path to a separate loop that does not interfere with the more sensitive analog control function. these two grounds must be connected together on the pc board layout at a single point. figure 8 shows a suggested layout for the critical com- ponents, based on the schematic on page 14. figure 8 - suggested layout. (topside shown only) 1 g m r 8 = 1 2 p 3 c 10 3 f p2 r 6 = - r 8 1 2 p 3 c 10 3 f z2 r 5 = 3 r 6 v ref v out - v ref c 5 d 1 d 2 iru3037 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 l1 l2 u1 q1 r4 c4 c9 c8 c3 r5 r6 c1 vin c2a, b c7a, b analog gnd pgnd pgnd vout pgnd d 3 single point analog gnd connect to power ground plane analog gnd
iru3037 / iru3037a 11 rev. 2.7 08/22/02 www.irf.com typical performance characteristics figure 9 - vcc vs. icc iru3037a vcc vs. icc @470pf, 1150pf and 1540pf gate load 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 vcc (v) icc (ma) t a = 25 8 c c load =1540pf c load =1150pf c load =470pf figure 10 - vc vs. ic iru3037a vc vs. ic @470pf, 1150pf and 1540pf gate load 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 18 20 22 24 26 vc (v) ic (ma) t a = 25 8 c c load =1540pf c load =1150pf c load =470pf
12 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com typical performance characteristics figure 11 - output voltage figure 12 - output frequency figure 13 - maximum duty cycle iru3037 output voltage 1.2 1.22 1.24 1.26 1.28 1.3 -40c 0c +50c +100c +150c volts output voltage spec max. spec min. max iru3037 output frequency 160 170 180 190 200 210 220 230 240 -40c 0c +50c +100c +150c kilo hertz oscillation frequency spec max. spec min. max iru3037 maximum duty cycle 80.0% 82.0% 84.0% 86.0% 88.0% 90.0% 92.0% -40c -25c 0c +25c +50c +75c +100c +125c +150c percent duty cycle max duty cycle min min
iru3037 / iru3037a 13 rev. 2.7 08/22/02 www.irf.com figure 16 - transconductance figure 15 - output frequency figure 14 - output voltage figure 17 - rise time and fall time iru3037 / iru3037a rise time / fall time cl = 1500pf 0 5 10 15 20 25 30 35 40 45 50 -40c -25c 0c +25c +50c +75c +100c nano seconds rise time fall time iru3037 / iru3037a transconductance ( gm ) 0 100 200 300 400 500 600 700 800 900 1000 -40c -25c 0c +25c +50c +75c +100c micro mho's positive load gm negative load gm iru3037a output voltage 760 770 780 790 800 810 820 -40c -25c 0c +25c +50c +75c +100c +150c milli volts output voltage spec max. spec min. max min iru3037a output frequency 300 320 340 360 380 400 420 440 460 -40c -25c 0c +25c +50c +75c +100c +150c kilo hertz oscillation frequency spec max. spec min. max min typical performance characteristics
14 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com typical application single supply 5v input figure 18 - typical application of iru3037 in an on-board dc-dc converter using a single 5v supply. iru3037 u1 vcc vc hdrv ldrv fb gnd comp ss c3 0.1uf c4 1uf c8 0.1uf c9 680pf r4 105k q1 1/2 of irf7301 q2 1/2 of irf7301 r5 1k, 1% r6 1.65k, 1% l2 d05022p-103, 10uh, 4.3a l1 1uh c2 2x 10tpb100ml, 100uf, 55m v c1 47uf tantalum 3.3v @ 4a c7 2x 6tpc150m, 150uf, 40m v c5 0.1uf d1 1n4148 d2 1n4148 d3 1n4148 5v
iru3037 / iru3037a 15 rev. 2.7 08/22/02 www.irf.com figure 19 - typical application of iru3037 or iru3037a in an on-board dc-dc converter providing the core, gtl+, and clock supplies for the pentium ii microprocessor. typical application dual supply, 5v bus and 12v bias input iru3037 u1 vcc vc hdrv ldrv fb gnd comp ss iru3037 u1 vcc vc hdrv ldrv fb gnd comp ss 12v iru1206-18 2.5v/2a 1.8v/1a r3 1k 1% c3 47uf c1 47uf l1 1uh c2 10tpb100m, 100uf, 55m v , 1.5a rms q1 1/2 of irf7752 l2 ctx5-2p, 3.5uh @ 2.5a q2 1/2 of irf7752 r1 1k, 1% c1 1uf c4 0.1uf c7 0.1uf c8 2200pf r2 14k c10 0.1uf c11 1uf c13 0.1uf c14 2200pf r5 14k r6 1k, 1% r4 1.65k, 1% q4 1/2 of irf7752 l3 ctx5-1p, 3.4uh @ 2a q3 1/2 of irf7752 c9 10tpb100m, 100uf, 55m v , 1.5a rms 3.3v/1.8a l2 ctx5-2p, 3.5uh @ 2.5a ctx10-5p, 5.7uh @ 2.5a c6 6tpb150m, 150uf, 55m v (qty 2) 6tpb150m, 150uf, 55m v (qty 1) c6 6tpb150m, 150uf, 55m v c12 6tpb150m, 150uf, 55m v 5v
16 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com typical application 1.8v to 7.5v / 0.5a boost converter figure 20 - typical application of iru3037 as a boost converter. ss comp vc hdrv fb vcc ldrv gnd iru3037 u1 r2 10k r3 20k vpwr (1.5v min) vcc v out (7.5v / 0.5a) gnd c9 2x 47uf d1 1n5817 l1 1uh (coiltronics up2b-1r0) c1 2x 68uf 5k, 1% 1k, 1% c8 1uf r4 25k r1 20k q2 2n2222 q1 2n2222 c5 1uf q3 irf7402 c4 0.01uf c5 0.1uf c10 100pf r5 r6
iru3037 / iru3037a 17 rev. 2.7 08/22/02 www.irf.com demo-board application 5v or 12v to 3.3v @ 10a ref desig description value qty part# manuf 1 1 1 3 1 1 1 2 2 2 1 1 1 3 1 1 1 1 q1 q2 u1 d1, d2, d4 l1 l2 c1 c2a, c2b c9b, c9c c5, c6 c3 c4 c7 c8, c13, c19 r3 r4 r5 r6 mosfet mosfet controller diode inductor inductor capacitor, tantalum capacitor, poscap capacitor, poscap capacitor, ceramic capacitor, ceramic capacitor, ceramic capacitor, ceramic capacitor, ceramic resistor resistor resistor resistor irf7457 irf7460 iru3037 ll4148 d03316p-102hc d05022p-332hc ecs-t1cd336r 16tpb47m 6tpc150m ecj-2vf1e104z ecj-3yb1e105k ecj-2vb1h222k ecj-2vb2d471k ecj-2vf1c105z ir ir ir coilcraft coilcraft panasonic sanyo sanyo panasonic panasonic panasonic panasonic panasonic application parts list 20v, 7m v , 15a 20v, 10m v , 12a synchronous pwm fast switching 1 m h, 10a 3.3 m h, 12a 33 m f, 16v 47 m f, 16v, 70m v 150 m f, 6.3v, 40m v 0.1 m f, y5v, 25v 1 m f, x7r, 25v 2200pf, x7r, 50v 470pf, x7r 1 m f, y5v, 16v 20k, 5% 4.7 v , 5% 1k, 1% 1.65k, 1% figure 21 - demo-board application of iru3037. iru3037 u1 vcc vc hdrv ldrv fb gnd comp ss l2 l1 gnd gnd v in 5v or 12v r6 q2 q1 irf7457 irf7460 d2 c2a 47uf 16v c2b 47uf 16v r3 20k c1 33uf 16v d1 ll4148 ll4148 c6 0.1uf 3.3uh c7 470pf r4 4.7 v c9b 150uf 6.3v c13 1uf 1uh c3 1uf c19 1uf c8 1uf c5 0.1uf c4 2200pf 1.65k d4 ll4148 v out 3.3v @ 10a r5 1k c9c 150uf 6.3v
18 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com figure 22 - efficiency for iru3037 evaluation board. figure 23 - start-up time @ i out =5a. figure 24 - shutdown the output by pulling down the soft-start. figure 25 - 3.3v output voltage ripple @ i out =5a. figure 26 - transient response @ i out = 0 to 2a. figure 27 - transient response @ i out = 0 to 4a. v in =5.0v, v out =3.3v 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 output current (a) efficiency (%) demo-board waveforms iru3037 iru3037 iru3037 iru3037 iru3037 2a 0a 0a 4a vss v out i out = 5v v in v out
iru3037 / iru3037a 19 rev. 2.7 08/22/02 www.irf.com (f) tssop package 8-pin symbol desig a b c d e f g h j k l m n o p q r r1 min 4.30 0.19 2.90 --- 0.85 0.05 0 8 0.50 0.09 0.09 nom 4.40 --- 3.00 --- 0.90 --- --- 0.60 --- --- 0.20 8-pin note: all measurements are in millimeters. max 4.50 0.30 3.10 1.10 0.95 0.15 8 8 0.75 --- --- 0.65 bsc 6.40 bsc 1.00 1.00 12 8 ref 12 8 ref 1.00 ref c b a 1.0 dia e f k h j g d p o m r r1 n l q detail a detail a pin number 1
20 rev. 2.7 08/22/02 iru3037 / iru3037a www.irf.com (s) soic package 8-pin surface mount, narrow body symbol a b c d e f g h i j k l t min 4.80 0.36 3.81 1.52 0.10 0.19 5.80 0 8 0.41 1.37 max 4.98 0.46 3.99 1.72 0.25 0.25 6.20 8 8 1.27 1.57 1.27 bsc 0.53 ref 7 8 bsc 8-pin note: all measurements are in millimeters. pin no. 1 i k h detail-a detail-a 0.38 6 0.015 x 45 8 t g f d a b c e l j
iru3037 / iru3037a 21 rev. 2.7 08/22/02 www.irf.com pkg desig f s package description tssop plastic soic, narrow body parts per tube 100 95 parts per reel 2500 2500 package shipment method pin count 8 8 t & r orientation fig a fig b feed direction figure a feed direction figure b 1 1 1 1 1 1 ir world headquarters: 233 kansas st., el segundo, california 90245, usa tel: (310) 252-7105 tac fax: (310) 252-7903 visit us at www.irf.com for sales contact information data and specifications subject to change without notice. 02/01

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