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product structure silicon monolithic integrated circuit this product ha s no designed protection against radioactive rays 1/ 23 www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 14 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 2.7v to 5.5v, 4a 1ch synchronous buck converter with integrated fet BD91361MUV general description BD91361MUV is rohms high efficiency step -down switching regulator designed to provide a voltage as low as 0. 8v from a supply voltage of 5 .5 v/3.3v . it offers high efficiency by using pulse skip control technology and synchronous switches, and provides fast transient response to sudden load changes by implementing current mode control. features ? fast transient response because of current m ode pwm control system ? h igh efficiency for all l oad ranges because of synchronous rectifier (nch/nch fet) and sllm tm (simple light load mode) ? soft-start function ? thermal shutdown and uvlo functions ? short-circui t protection with time delay function ? shutdown function applications power supply for lsi including dsp, microcomputer and asic key specifications ? input voltage range: 2.7v to 5.5v ? output voltage range: 0.8v to 3.3v ? output current: 4.0a (max) ? switching frequency: 1mhz(typ) ? high side fet on-resistance: 60m ? (typ) ? low side fet on-resistance: 55m ? (typ) ? standby current: 0a (typ) ? operating temperature range: - 40 c to +105 c package w(typ) x d(typ) x h(max) typical application circuit figure 1. typical application circuit vqfn020v4040 4.00mm x 4.00mm x 1.00mm sw pvcc en adj ith v cc c in r ith c ith l c o r 2 v out c bst vcc c f r f vid<1> vid<0> v cc r 1 datashee t downloaded from: http:///
2/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 pin configuration pin description pin no. pin name function pin no. pin name function 1 sw power switch node 11 gnd ground pin 2 sw power switch node 12 adj output voltage detection pin 3 sw power switch node 13 ith gmamp output pin/c on nected to phase compensation capacitor 4 sw power switch node 14 vid<1> output voltage control pin<1> 5 sw power switch node 15 vid<0> output voltage control pin<0> 6 pvcc power switch supply pin 16 n.c. no connection 7 pvcc power switch supply pin 17 en enable pin (active high) 8 pvcc power switch supply pin 18 pgnd power switch ground pin 9 bst bootstrapped voltage input pin 19 pgnd power switch ground pin 10 vcc power supply input pin 20 pgnd power switch ground pin block diagram figure 2 . pin configuration 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 bst n.c. sw pvcc vcc gnd adj ith vid <0> en pgnd vid <1> (top view) figure 3 . block diagram output pgnd gnd gm amp r s q osc + v cc vcc clk slope en current comp soft start current sense/ protect + driver logic + ith r ith c ith pvcc sw pv cc bst v cc input adj vref uvlo tsd scp selector r1 r2 vid<0> vid<1> r 1 r 2 r ith c ith vcc pvcc downloaded from: http:///
3/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 absolute maximum ratings (ta=25 c ) parameter symbol rating unit vcc voltage v cc -0.3 to +7 (note 1) v pvcc voltage pv cc -0.3 to +7 (note 1) v bst voltage v bst -0.3 to +13 v bst _sw voltage v bst - sw -0.3 to +7 v en voltage v en -0.3 to +7 v sw ,i th voltage v sw , v ith -0.3 to +7 v power dissipation 1 p d1 0.34 (note 2) w power dissipation 2 p d2 0.70 (note 3) w power dissipation 3 p d3 2.21 (note 4) w power dissipation 4 p d4 3.56 (note 5) w operating temperature range topr -40 to +105 c storage temperature range tstg -55 to +150 c maximum junction temperature tjmax +150 c (note 1) pd should not be exceed ed . (note 2) ic only (note 3) mounted on a 1-layer 74.2mmx74.2mmx1.6mm glass-epoxy board, occupied area by copper fo il : 10.29mm 2 (note 4) mounted on a 4-layer 74.2mmx74.2mmx1.6mm g lass-epoxy board, 1st and 4th copper foil area : 10 .29mm 2 , 2nd and 3rd copper foil area : 5505mm 2 (note 5) mounted on a 4-layer 74.2mmx74.2mmx1.6mm glass-epoxy board, occupied area by copper fo il : 5505mm 2 , in each layers caution: operating the ic over the absolute maximum ratings may damage the ic. in addition, it is impossible to predict all destructive situations such as short-circuit modes, open circuit modes, etc. therefore, it is important to consi der circuit protection measures, like adding a fuse, in case the ic i s operated in a special mode exceeding the absolute maximum ratings. recommended operating conditions (ta=- 40 c to +105 c ) parameter symbol rating unit min typ max power supply voltage v cc 2.7 3.3 5.5 v pv cc 2.7 3.3 5.5 v en voltage v en 0 - 5.5 v logic input voltage v vid<1:0> 0 - 5.5 v output voltage setting range v out 0.8 - 3.3 (note 6) v sw average output current i sw - - 4.0 (note 7) a (note 6) in case the output voltage is set to 1.6v or more, v cc m in = v out +1.2v. (note 7) pd should not be exceed ed . electrical characteristics (unless otherwise specified, ta=25 c v cc =pv cc =3.3v, v en =v cc , vid<1>=vid<0>=0v, r 1 =10k ? , r 2 =5k ? ) parameter symbol limit unit conditions min typ max standby current i stb - 0 10 a en=gnd active current i cc - 250 500 a en low voltage v enl - gnd 0.8 v standby mode en high voltage v enh 2.0 v cc - v active mode en input current i en - 3 10 a v en =3.3v vid low voltage v vidl - gnd 0.8 vid high voltage v vidh 2.0 v cc - vid input current i vid - 3 10 v vid =3v oscillation frequency f osc 0.8 1 1.2 mhz high side fet on-resistance r onh - 60 90 m ? pv cc =3.3v low side fet on-resistance r onl - 55 85 m ? pv cc =3.3v adj voltage v adj 0.788 0.800 0.812 v v vid<1:0> =(0,0) ith sink current i thsi 10 18 - a v adj =1v ith source current i thso 10 18 - a v adj =0.6v uvlo threshold voltage v uvlo1 2.400 2.500 2.6 00 v v cc =3.3v to 0v uvlo release voltage v uvlo2 2.425 2.550 2.700 v v cc =0v to 3.3v soft-start time t ss 0.5 1 2 ms timer latch time t latch 0.5 1 2 ms output short circuit threshold voltage v scp - 0.40 0.56 v v adj =0.8v to 0v downloaded from: http:///
4/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 typical performance curv es figure 4. output voltage vs input voltage output voltage: v out [v] input voltage: v cc [v] [v out =1.2v] ta=25c i o =3a figure 7. output voltage vs temperature output voltage: v out [v] temperature: ta[c] figure 6. output voltage vs output current output voltage: v out [v] output current: i out [a] figure 5. output voltage vs en voltage output voltage: v out [v] en voltage: v en [v] [v out =1.2v] v cc =5v ta=25c i o =3a [v out =1.2v] ta=25c v cc =5v v cc =2.7v [v out =1.2v] v cc =5v i o =0a downloaded from: http:///
5/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 typical performance curves - continued figure 8. efficiency vs output current efficiency: [%] output current: i out [ma] f? v out =1.2v f? v cc =5v ta=25c figure 10 . on -resistance vs temperature on -resistance: r on [ ] temperature: ta [c] v cc =3.3v figure 11. en voltage vs temperature en voltage : v en [v] temperature: ta [c] figure 9. frequency vs temperature frequency: f osc [khz] temperature: ta [c] v cc =5v v cc =5v downloaded from: http:///
6/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 typical performance curves - continued figure 12. circuit current vs temperature temperature: ta [c] circuit current: v out [ a] figure 13 . frequency vs input voltage frequency: f osc [khz] input voltage: v cc [v] v cc =5v ta=25c downloaded from: http:///
7/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 typical waveforms figure 14 . soft-start waveform v cc =5v ta=25c i o =0a [v out =1.2v] v out v cc =pv cc =en figure 16 . sw waveform (i o =4a) v cc = 5v v out =1.2v] [pwm control sw figure 17 . transient response (i o =1a to 4a , 20s) v cc = 5v [v out =1.2v] v out i out figure 15 . sw waveform (i o =0ma) v out v out =1.2v] v cc =5v ta=25c sw [sllm tm control downloaded from: http:///
8/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 typical waveforms - continued figure 20 . change response figure 18 . transient response (i o =4a to 1a , 20s) v cc = 5v v o ut i out [v out =1.2v] [v out =1.2v] figure 19 . change response [v out =1.2v] downloaded from: http:///
9/ 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 application information 1. operation BD91361MUV is a synchronous step-down switching regulator that achieves fast transient response by emplo ying current mode pwm control system. it utilizes switching operation in pwm (pulse width modulation) mode for heavier load, while it utilizes sllm tm (simple light load mode) operation for lighter load to improve efficiency. (1) synchronous rectifier integrated synchronous rectification using two mosfets reduces power dissipation and increases efficiency when compared to converters using external diodes. internal shoot-through current limiting circuit further reduces power dissipation. (2) current mode pwm control the pwm control signal of this ic depends on two feedback loops, the voltage feedback and the inductor current feedback. (a) pwm (pulse width modulation) control the clock signal coming from osc has a frequency of 1mhz. when osc sets the rs latch, the p-channel mosfet is turned on and the n-channel mosfet is turned off . the opposite happens when the current comparator (current comp) resets the rs latch i.e. the p-channel mosfet is turned off and the n-channel mosfet is turned on . current comps output is a comparison of two signals, the current feedback control signal sense which is a voltage proportional to the current i l , and the voltage feedback control signal, fb. (b) sllm tm (simple light load mode) control when the control mode is shifted by pwm from heavier load to lighter load or vice versa, the switching pulse is designed to turn off with the device held operating in normal pwm control loop. this allows linear operation without voltage drop or deterioration in transient response during the sudden load changes. although the pwm control loop continues to operate with a set signal from osc and a reset signal from current comp, it is so designed such that the reset signal is continuously sent even if the load is changed to light mode where the switching is tuned off and the switching pulses disappear. activating the switching discontinuously red uces the switching dissipation and improves the efficiency. figure 21. diagram of current mode pwm control figure 22 . pwm switching timing diagram figure 23 . sllm tm switching timing diagram osc level shift driver logic r q s i l sw r ith current comp gm amp set reset fb load sense v out v out current comp set reset sw v out pv cc gnd gnd gnd i l (ave) v out (ave) sense fb current comp set reset sw v out pv cc gnd gnd gnd 0a v out (ave) sense fb i l not switching i l downloaded from: http:///
10 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 2. description of functions (1) soft-start function during start-up, the soft-start circuit gradually establishes the output voltage to limit the input current. this prevents the overshoot in the output voltage and inrush current. (2) shutdown function when en terminal is set to low, the device operates in standby mode, and all the function al blocks such as reference voltage circuit, internal oscillator and drivers are turned to off. circuit current during standby is 0a (typ). (3) uvlo function this circuit detects whether the supplied input voltage is sufficient to provide the output voltage of this ic. a hysteresis width of 50mv (typ) is provided to prevent the output from chattering. figure 24 . soft-start, shutdown, uvlo timing chart (4) short-circuit protection with time delay function to protect the ic from breakdown, the short-circuit turns the output off when the internal current limiter is activated continuously for a fixed time (t latch ) or more. the output that is kept off may be turned on again by restarting en or by resetting uvlo. figure 25 . short-circuit protection with time delay diagram hysteresis 50mv t ss t ss t ss soft start standby mode operating mode standby mode operating mode standby mode operating mode standby mode uvlo en uvlo uvlo v cc en v out 1/2v out 1msec output voltage off latch output current in non-control output current in control by limit value (with fall of the output voltage, limit value goes down) en timer latch en standby mode operated mode standby mode operated mode en v out limit i l until output voltage goes up the half of v o or over, timer latch is not operated. (no timer latch, only limit to the output current) downloaded from: http:///
11 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 3. information on advantages advantage 1: offers fast transient response by using current mode control system. voltage drop due to sudden change in load was reduced. figure 26. comparison of transient response ad vantage 2: offers high efficiency for all load ranges. (a) for lighter load: this ic utilizes the current mode control called sllm tm , which reduces various dissipations such as switching dissipation (p sw ), gate charge/discharge dissipation (p gate ), esr dissipation of output capacitor (p esr ) and on -resistance dissipation (p ron ) that may otherwise cause reduction in efficiency. achieves efficiency improvement for lighter load. (b) for heavier load: this ic utilizes the synchronous rectifying mode and uses low on-resistance power mosfets. on-resistance of high side mosfet : 60m ? (typ) on -resistance of low side mosfet : 55m ? (typ) achieves efficiency improvement for heavier load. offers high efficiency for all load ranges with the improvements mentioned above. advantage 3: ? supplied in smaller package due to small- si zed power mos fet. reduces mounting area requirement. figure 28 . example application figure 27 . efficiency ? required output capacitance, c o ,for current mode control: 22f ceramic capacitor ? required inductance, l, for the operating frequency of 1 mhz: 2.2 h inductor ? incorporates fet + boot strap diode 0.001 0.01 0.1 1 0 50 100 pwm sllm tm improvement by sllm system improvement by synchronous rectifier efficiency [%] output current i out [a ] conventional product (load response i o =1a to 3a) BD91361MUV (load response i o =1a to 3a) v out i out 145mv v out i out 62mv output pgnd gnd gm amp + vcc vcc clk slope en current comp soft start current sense/ protect + driver logic + ith r ith c ith pvcc sw pvc c bst vcc input adj vid<0> uvlo scp r 1 r 2 tsd vid<1> selector vref 15mm 20mm r 2 c ith c f co l r 1 r ith rf c bst c in downloaded from: http:///
12 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 4. setting the output voltage output voltage shifts step by step, depending on the bit setting, to control the overshoot/undershoot that happens when changing the setting of output voltage. a delay of 8 steps (max) will occur from the bit switching until output vol tage reaches the setting value. (a) switching 2 bits synchronously (c) switching the bit during counting (b) switching 2 bits with the time lag figure 29. timing diagram of setting the output voltage it is possible to set the output voltage by setting vid<0> to <1> 0 or 1, as shown in the table below. by default, vid<1:0> terminal is set to (0,0) by the high impedance pull down resistor inside the ic. by pulling up/down the resistor for about 10k ? , the default value can be changed . diagram 1. table of output voltage setting vid<1> vid<0> v out 0 0 v out 0 1 0.9 x v out 1 0 1.1 x v out 1 1 1.2 x v out (note ) after 10s(max) from the bit change, v out starts to change . requir ed time for one step (10% shift of v out ) of v out is 10s(max). from bit switching until the output voltage reach es t he setting value, a delay of t vid (max)=0.04ms will occur. v out v id <2:0> (0,1) (1,1) 0.96v 0.72v t vid (max)=0.04ms v out count stop about 10s from switching the last bit vid<1> vid<0> <1> v out <0> count stop about 10s from bit switching v out count stop about 10s from bit switching v id <1> v id <0> 5s(max) downloaded from: http:///
13 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 5. switching regulator efficiency efficiency may be expressed by the equation shown below: efficiency may be improved by reducing the switching regulator power dissipation factors pd as follows: dissipation factors: (1) on -resistance dissipation of inductor and fet pd (i 2 r) where: r coil is the dc resistance of inductor. r on is the on-resistance of fet. i out is the output current. (2) gate charge/discharge dissipation pd(gate) where: c gs is the gate capacitance of fet. f is the switching frequency. v is the gate driving voltage of fet. (3) switching dissipation pd(sw) where: c rss is the reverse transfer capacitance of fet. i drive is the peak current of gate. (4) esr dissipation of capacitor pd(esr) where i rms is the ripple current of capacitor. esr is the equivalent series resistance. (5) operating current dissipation of ic pd(ic) where: i cc is the circuit current. ? ? % 100 100 100 ? ? ? ? ? ? ? ? ? ? ? pd p p p p i v i v out out in out in in out out ? ? ? ? on coil out r r i ri pd ? ? ? 2 2 cc in i v ic pd ? ? )( esr i esr pd rms ? ? 2 ) ( drive out rss in i f i c v sw pd ? ? ? ? 2 ) ( ? ? 2 v f c gate pd gs ? ? ? downloaded from: http:///
14 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 6. consideration on permissible dissipation and heat generation since this ic functions with high efficiency without significant heat generation in most applications, no special consideration is needed on permissible dissipation or heat generation. in case of extreme conditions , (such as lower input voltage, higher output voltage, heavier load, and/or higher temperature), the permissible dissipation and/or heat ge neration must be carefully considered. for dissipation, only conduction losses due to dc resistance of inductor and on-resistance of fet are considered. th is is because th e conduction losses are the most significant among other dissipation mentioned above including gate charge/discharge dissipation and switching dissipation. if v cc =3.3v, v out =1.8v, r onh =60m ? , r onl =55m ? i out =4a ? ? ? ? ? ? w p r v v d on cc out 2309 .0 0577 .0 4 0577 .0 0250 .0 0327 .0 55 .0 545 .01 06 .0 545 .0 545 .0 3.3/8.1 / 2 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? since r onh is greater than r onl in this ic, the dissipation increases as the on duty time increases. taking into consideration the dissipation as shown above, thermal design must be carried out with allowable sufficient margin. figure 30 . thermal derating curve (vqfn020v4040) ? ? onl onh on on out r d r d r r i p ? ? ? ? ? ? 1 2 where: d is the on duty (=v out /v cc ). r onh is the on -resistance of highs ide mosfet. r onl is the on -resistance of lowside mosfet. i out is the output current. 4 layers (copper foil area : 5505mm 2 ) copper foil in each layers. j -a=35.1 c /w 4 layers (1 st and 4 th copper foil area : 10.29m 2 ) (2 nd and 3 rd copper foil area: 5505m 2 ) j -a=56.6 c /w 1 layer (copper foil area : 10.29m 2 ) j -a=178.6 c /w ic only. j -a=367.6 c /w 0 1 2 3 4 0 25 50 75 100 125 150 ambient temperature:ta power dissipation:pd [w] 105 [ c] 3.56w 2.21w 0.70w 0.34w downloaded from: http:///
15 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 7. selection of components externally connected (1) selection of inductor (l) note: current exceeding the current rating of the inductor results in magnetic saturation of the inductor, which decreases efficiency. the inductor must be selected allowing sufficient margin with which peak current may not exceed its current rating. if v cc =5.0v, v out =1.2v, f=1mhz, i l =0.2x3a=0.6a, for example , ( BD91361MUV) note: select an inductor with low resistance (such as dcr and acr) to minimize inductor dissipation for better efficiency. (2) selection of output capacitor (c o ) (3) selection of input capacitor (c in ) a low esr 22f/10v ceramic capacitor is recommended to reduce esr dissipation of input capacitor for better efficiency. the inductance significantly affects the output ripple current. as seen in the equation (1), the ripple current decreases as the inductor and/or switching frequency increases. appropriate ripple current at output should be 20% of the maximum output current. output capacitor should be selected with the consideration on the stability region and the equivalent series resistance required to minimize ripple voltage. output ripple voltage is determined by the equation (4): note: rating of the capacitor should be determined by allowing sufficient margin against output voltage. a 22f to 100f ceramic capacitor is recommended. less esr allows reduction in output ripple voltage. figure 32. output capacitor i l v out figure 31. output ripple current i l v cc i l l c o v cc l c o v out esr fi gure 33 . input capacitor v out v cc l co c in input capacitor must be a low esr capacitor with capacitance sufficient to cope with high ripple current to prevent high transient voltage. the ripple curren t i rms is given by the equation (5 ): < worst case > i rms max if v cc =3.3v, v out =1.8v, and i outm ax = 3a, (BD91361MUV) ? ? ? ? a f v l v v v i cc out out cc l ? ? ? ? ? ? ??? (1) ? ? a i i outmax l ? ? ? 2.0 ??? (3) ? ? ? ? h f v i v v v l cc l out out cc ? ? ? ? ? ? ??? (2) where: i l is the output ripple current. f is the switching frequency. ? ? ? ? h m l ? ? 0.2 52 .1 156.0 2.1 2.10.5 ? ? ?? ? ? ? ??? (4) ? ? v esr i v l out ? ?? ? where: i l is the output ripple current. esr is the equivalent series resistance of output capacitor. ??? (5) ? ? ? ? a v v v v i i cc out cc out out rms ? ? ? 2 i i, v 2 v out rms out cc ? ? ? ? ? ? ? rms rms a i 49 .1 3.3 8.1 3.38.1 3 ? ? ? ? downloaded from: http:///
16 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 (4) calculating r ith , c ith for phase compensation since the current mode control is designed to limit a inductor current, a pole (phase lag) appears in the low frequency area due to a cr filter consisting of a output capacitor and a load resistance, while a zero (phase lead) appears in the high frequency area due to the output capacitor and its esr. therefore, the phases are easily compensated by adding a zero to the power amplifier output with c and r as described below to cancel a p ole at the power amplifier. figure 36 . typical application stable feedback loop may be achieved by canceling the pole fp(min) produced by the output cap acitor and the load resistance. this is done by using cr zero correction of the error amplifier. figure 34 . open loop g ain characteristics figure 35 . error amp phase compensation characteristics a 0 0 - 90 f z (amp) gain [db] phase [deg] gain [db] phase [deg] a 0 0 - 90 fp(min) fp(max) f z (esr) i outm in i outm ax pole at power amplifier when the output current decreases, the load resistance ro increases and the pole frequency decreases. zero at power amplifier increasing capacitance of the output capacitor lowers the pole frequency while zero frequency does not change. (this is because when the capacitance is doubled, the capacitor esr is reduced to half.) o o c r fp ? ? ? ? 2 1 ? ? o esr z c esr f ? ? ? ? 2 1 ? ? ? ? load lighter with hz c r fp o omax min ? ? ? ? ? 2 1 ? ? ? ? load heavier with hz c r fp o omin max ? ? ? ? ? 2 1 ? ? ith ith amp z c r f ? ? ? ? 2 1 ? ? ? ? o omax ith ith min p amp z c r c r f f ? ? ? ? ? ? ? ? ? 2 1 2 1 gnd,pgnd sw pvcc en adj ith v cc c in r ith c ith l c o r 2 v out c bst vcc c f rf vid<1> vid<0> v cc v cc r 2 downloaded from: http:///
17 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 (5) setting the output voltage the output voltage v out is determined by the equation (6 ): ? ? adj out v r r v ? ? ? 1 / 1 2 ??? (6) where: v adj : voltage at adj terminal (0.8v typ) the required output voltage may be determined by adjusting r 1 and r 2 . figure 37 . determination of output voltage adjustable output voltage range: 0.8v to 3.3v use 1 k? to 100 k? resistor for r 1 . if the resistance is higher than 100 k? , carefully check the assembled set for ripple voltage etc. v v v out ccmin 2.1 ? ? 8. BD91361MUV cautions on pc board layout figure 39 . layout diagram (1) layout the input ceramic capacitor c in as close as possible to the pv cc and pgnd pins, and the output capacitor c o as close as possible to the pgnd pin . (2) layout c ith and r ith between the pins ith and gnd as near as possible with the shortest possible trace. note: vqfn020v4040 (BD91361MUV) has thermal pad on the reverse of the package. the package thermal performance may be enhanced by bonding the pad to gnd plane which occupies a la rge area of the pcb. sw 6 1 adj l c o r 2 r 1 output figure 38 . minimum input voltage in each output voltage the lower limit of input voltage depends on the output voltage. basically, the recommended operating condition is figure 38. shows the necessary output current value at the lower limit of input voltage. (dcr of inductor : 20m ? ) this data is the characteristic value, so it doesn t guarantee the operation range. v o =2.5v v o =2.0v v o =1.8v 2.7 2.9 3.1 3.3 3.5 3.7 0 1 2 3 input voltage : v cc [v] output current : i out [a] downloaded from: http:///
18 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 9. recommended components lists on above application symbol part value manufacturer series l coil 2.0h sumida cdr6d28mnnp-2r0nc c in ceramic capacitor 22f murata grm32eb11a226ke20 c o ceramic capacitor 2 2f murata grm31cb30j226ke18 c ith ceramic capacitor v out =1.2v 1000pf murata grm18 series r ith resistance 6.8k ? rohm mcr03 series c f ceramic capacitor 1000 pf murata g rm 18 series r f resistance 10 ? rohm mcr03 series c bst ceramic capacitor 0.1f murata g rm 18 series note: the parts list presented above is an example of recommended parts. although the parts are standard, actual circuit characteristics should be carefully checked on your application before use. be sure to allow a sufficient margin to accommodate variations between external devices and this ic when employing the depicted circuit with other circuit constants modified. both static and transient characteristics should also be considered in establishing these margins. when switching noise is significant and may affect the system, a low pass filter should be inserted between th e vcc and pvcc pins, and a schottky barrier diode or snubber established between the sw and pgnd pins. i/o equivalent circuit figure 40 . i/o equivalent circuit ? en pin en ? sw pin pv cc sw pv cc pv cc ? ith pin ith v cc ? adj pin adj pv cc bst ? bst pin pv cc sw ? vid pin ( vid<0>, vid<1> are the same composition vid downloaded from: http:///
19 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 operational notes 1. reverse connection of power s upply connecting the power supply in reverse polarity can damage the ic. take precautions against reverse polarity when connecting the power supply, such as mounting an external diode between the power supply and the ic s power supply pins. 2. power supply lines design the pcb layout pattern to provide low impedance supply lines. separate the ground and supply lines of the digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog block. furthermore, connect a capacitor to ground at all power supply pins . consider the effect of temperature and aging on the capacitance value when using electrolytic capacitors. 3. ground voltage ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition. 4. ground wiring pattern when using both small-signal and large-current ground traces, the two ground traces should be routed separately but connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal ground caused by large currents. also ensure that the ground traces of external components do not cause variations on the ground voltage. the ground lines must be as short and thick as possible to reduce line impedance. 5. thermal consideration should by any chance the power dissipation rating be exceeded the rise in temperature of the chip may result in deterioration of the properties of the chip. in case of exceeding this absolute maximum rating, increase the board size and copper area to prevent exceeding the pd rating. 6. recommended operating conditions these conditions represent a range within which the expected characteristics of the ic can be approximately obtained . the electrical characteristics are guaranteed under the conditions of each parameter. 7. inrush current when power is first supplied to the ic, it is possible that the internal logic may be unstable and inrush current may flow instantaneously due to the internal powering sequence and delays, especially if the ic has more than one power supply. therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and routing of connections. 8. operation under strong electromagnetic field operating the ic in the presence of a strong electromagnetic field may cause the ic to malfunction. 9. testing on application boards when testing the ic on an application board, connecting a capacitor directly to a low-impedance output pin ma y subject the ic to stress. always discharge capacitors completely after each process or step. the ic s power supply should always be turned off completely before connecting or removing it from the test setup during the inspection process. to prevent damage from static discharge, ground the ic during assembly and use similar precautions during transport and storage. 10. inter-pin short and mounting errors ensure that the direction and position are correct when mounting the ic on the pcb. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each other especially to ground, power supply and outp ut pin . inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and unintentional solder bridge deposited in between pins during assembly to name a few. downloaded from: http:///
20 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 operational notes C continued 11. unused input pins input pins of an ic are often connected to the gate of a mos transistor. the gate has extremely high impedance and extremely low capacitance. if left unconnected, the electric field from the outside can easily charge it. the small charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and cause unexpected operation of the ic. so unless otherwise specified, unused input pins should be connected to the power supply or ground line. 12. regarding the input pin of the ic this monolithic ic contains p+ isolation and p substrate layers between adjacent elements in order to keep them isolated. p-n junctions are formed at the intersection of the p layers with the n layers of other elements, creating a parasitic diode or transistor. for example (refer to figure below): when gnd > pin a and gnd > pin b, the p-n junction operates as a parasitic diode. when gnd > pin b, the p-n junction operates as a parasitic transistor. parasitic diodes inevitably occur in the structure of the ic. the operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. therefore, conditions that cause these diode s to operate, such as applying a voltage lower than the gnd voltage to an input pin (and thus to the p s ubstrate) should be avoided. figure 41. example of monolithic ic structure 13. thermal shutdown circuit(tsd) this ic has a built-in thermal shutdown circuit that prevents heat damage to the ic. normal operation should alway s be within the ics power dissipation rating. if however the rating is exceeded for a continued perio d, the junction temperature (tj) will rise which will activate the tsd circuit that will turn off all output pins. when the t j falls below the tsd threshold, the circuits are automatically restored to normal operation. note that the tsd circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set design or for any purpose other than protecting the ic from heat damage. 14. selection of inductor it is recommended to use an inductor with a series resistance element (dcr) 0.1 ? or less. especially, note that use of a high dcr inductor will cause an inductor loss, resulting in decreased output voltage. should this condi tion continue for a specified period (soft start time + timer latch time), output short circuit protection will be activated and output will be latched off. when using an inductor over 0.1 ? , be careful to ensure adequate margins for variation between external devices and this ic, including transient as well as static characteristics. furthermore, in any case, it is recommended to start up the output with en after supply voltage is within. n n p + p n n p + p substrate gnd n p + n n p + n p p substrate gnd gnd parasitic elements pin a pin a pin b pin b b c e parasitic elements gnd parasitic elements c be transistor (npn) resistor n region close-by parasitic elements downloaded from: http:///
21 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 ordering information b d 9 1 3 6 1 m u v e 2 part number type adjustable (0.8v to 3.3v) package muv : vqfn020v4040 packaging and forming specification e2: embossed tape and reel marking diagram vqfn020v4040 (top view) 1 part number marking lot number 1pin ma rk d 9 1 3 6 downloaded from: http:///
22 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 physical dimension, tape and reel information package name vqfn020v4040 downloaded from: http:///
23 / 23 BD91361MUV datas heet www.rohm.com ? 2012 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 tsz02201-0j3j0aj00200-1-2 06.oct.2014 rev.002 revision history date revision changes 02.mar.2012 001 new release 06.oct.2014 002 applied the rohm standard style and improved understandability. downloaded from: http:///
notice C ge rev.003 ? 2014 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. our products are designed and manufactured for application in ordinary electronic equipments (such as av equipment, oa equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). if you intend to use our products in devices requiring extremely h igh reliability (such as medical equipment (note 1) , transport equipment, traffic equipment, aircraft/spacecraft, nuclear power c ontrollers, fuel controllers, car equipment including car accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or serious damage to property (specific applications), please c onsult with the rohm sales representative in advance. unless otherwise agreed in writing by rohm in advance, rohm s hall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arisin g from the use of any rohms products for specific applications. (note1) medical equipment classification of the specific appli cations japan usa eu china class class class b class class | class 2. rohm designs and manufactures its products subject to s trict quality control system. however, semiconductor products can fail or malfunction at a certain rate. please be sure to implement, at your own responsibilities, adeq uate safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which a failure or malfunction of our products may cause. the followi ng are examples of safety measures: [a] installation of protection circuits or other protective devic es to improve system safety [b] installation of redundant circuits to reduce the impact of single or multiple circuit failure 3. our products are designed and manufactured for use under standard conditions and not under any special or extraordinary environments or conditions, as exemplified be low. accordingly, rohm shall not be in any way responsible or liable for any damages, expenses or losses arising from the use of any rohms products under any special or extraordinary environments or conditions. if you intend to use our products under any special or extraordinary environments or conditions (as exemplified belo w), your independent verification and confirmation of product performance, reliability, etc, prior to use, must be n ecessary: [a] use of our products in any types of liquid, including water, oils, chemicals, and organi c solvents [b] use of our products outdoors or in places where the products are exposed to direct sunlight or dust [c] use of our products in places where the products are ex posed to sea wind or corrosive gases, including cl 2 , h 2 s, nh 3 , so 2 , and no 2 [d] use of our products in places where the products are exposed to static electricity or electromagnetic waves [e] use of our products in proximity to heat-producing components , plastic cords, or other flammable items [f] sealing or coating our products with resin or other coating materials [g] use of our products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of flux is recommended); or washing our products by using water or water-soluble cleaning agents for cleaning residue after soldering [h] use of the products in places subject to dew condensation 4. the products are not subject to radiation-proof design. 5. please verify and confirm characteristics of the final or mou nted products in using the products. 6. in particular, if a transient load (a large amount of load a pplied in a short period of time, such as pulse. is applied, confirmation of performance characteristics after on-board moun ting is strongly recommended. avoid applying power exceeding normal rated power; exceeding the power rating u nder steady-state loading condition may negatively affect product performance and reliability. 7. de -rate power dissipation (pd) depending on ambient temperature (ta). whe n used in sealed area, confirm the actual ambient temperature. 8. confirm that operation temperature is within the specified range described in the product specification. 9. rohm shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in this document. precaution for mounting / circuit board design 1. when a highly active halogenous (chlorine, bromine, e tc.) flux is used, the residue of flux may negatively affect p roduct performance and reliability. 2. in principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method mus t be used on a through hole mount products. i f the flow soldering method is preferred on a surface-mount p roducts , please consult with the rohm representative in advance. for details, please refer to rohm mounting specification downloaded from: http:///
notice C ge rev.003 ? 2014 rohm co., ltd. all rights reserved. precautions regarding application examples and external circuits 1. if change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the characteristics of the products and external components, incl uding transient characteristics, as well as static characteristics. 2. you agree that application notes, reference designs, and associated data and information contained in this docu ment are presented only as guidance for products use. therefore, i n case you use such information, you are solel y responsible for it and you must exercise your own independ ent verification and judgment in the use of such information contained in this document. rohm shall not be in any way respon sible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such informat ion. precaution for electrostatic this product is electrostatic sensitive product, which may b e damaged due to electrostatic discharge. please take pro per caution in your manufacturing process and storage so t hat voltage exceeding the products maximum rating will not be applied to products. please take special care under dry con dition (e.g. grounding of human body / equipment / solder iron , isolation from charged objects, setting of ionizer, friction prevention and temperature / humidity control). precaution for storage / transportation 1. product performance and soldered connections may deteriorate if the products are stored in the places where: [a] the products are exposed to sea winds or corrosive gases, inc luding cl2, h2s, nh3, so2, and no2 [b] the temperature or humidity exceeds those recommended by rohm [c] the products are exposed to direct sunshine or condensation [d] the products are exposed to high electrostatic 2. even under rohm recommended storage condition, solderab ility of products out of recommended storage time period may be degraded. it is strongly recommended to confirm so lderability before using products of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the correct direction, which is in dicated on a carton with a symbol. otherwise bent leads may occur due to excessive stress applied when dropping of a c arton. 4. use products within the specified time after opening a hum idity barrier bag. baking is required before using products of which storage time is exceeding the recommended storage tim e period. precaution for product label qr code printed on rohm products label is for rohm s internal use only. precaution for disposition when disposing products please dispose them properly usin g an authorized industry waste company. precaution for foreign exchange and foreign trade act since our products might fall under controlled goods prescr ibed by the applicable foreign exchange and foreign trade act, please consult with rohm representative in case of export. precaution regarding intellectual property rights 1. all information and data including but not limited to ap plication example contained in this document is for referen ce only. rohm does not warrant that foregoing information or da ta will not infringe any intellectual property rights or any other rights of a ny third party regarding such information or data. rohm shall not be in any way responsible or liable for infringement of any intellectual property rights or other d amages arising from use of such information or data.: 2. no license, expressly or implied, is granted hereby under any i ntellectual property rights or other rights of rohm or any third parties with respect to the information contained in this d ocument. other precaution 1. this document may not be reprinted or reproduced, in whole or in part, without prior written consent of rohm. 2. the products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written consent of rohm. 3. in no event shall you use in any way whatsoever the products and the related technical information contained in the products or this document for any military purposes, includi ng but not limited to, the development of mass-destruction weapons. 4. the proper names of companies or products described i n this document are trademarks or registered trademarks of rohm, its affiliated companies or third parties. downloaded from: http:///
datasheet datasheet notice C we rev.001 ? 2014 rohm co., ltd. all rights reserved. general precaution 1. before you use our pro ducts, you are requested to care fully read this document and fully understand its contents. rohm shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny rohms products against warning, caution or note contained in this document. 2. all information contained in this docume nt is current as of the issuing date and subj ec t to change without any prior notice. before purchasing or using rohms products, please confirm the la test information with a rohm sale s representative. 3. the information contained in this doc ument is provi ded on an as is basis and rohm does not warrant that all information contained in this document is accurate an d/or error-free. rohm shall not be in an y way responsible or liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or concerning such information. downloaded from: http:///

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