NJU7631 -1- ver.2006-07-12 step-down switching regulator ic with power saving pwm/pfm control general description package outline features product variation automatic pwm/pfm control operating voltage 2.2v to 8v wide oscillator range 300khz to 1mhz maximum duty cycle 100% quiescent current 800 a typ. soft-start function internal : 16ms typ. or adjustable dead time control timer latch for short circuit protection c-mos technology package outline NJU7631rb1 : tvsp8 ** planning pin configuration NJU7631 is a high speed low voltage operation switching regulator control ic with power saving pwm/pfm control. automatic pwm/pfm control improves power efficiency at ligh t load. it features a totem pole driver that can directly drive an external mos-fet. internal soft-start function, dead time control and timer latch function are included, requiring no external components. all parameters can be optimized by additional external components fo r desi g n flexibilit y . NJU7631rb1 pin function 1. out 2. v + 3. fb 4. in - 5. scp 6. dtc 7. rt 8. gnd NJU7631rb1 1 8 2 7 3 6 4 5 NJU7631 nju763x** standby function pwm/pfm nju7630 pwm control pwm/pfm light load to efficiency
NJU7631 - 2 - ver.2006-07-12 block diagram buffer 0.5v osc 1v 0.5 r t a 2k ? 2 ? amp latch 0.8v 0.2v pwm pwm/pfm control
NJU7631 - 3 - ver.2006-07-12 absolute maximum ratings (ta=25c) parameter symbol maximum ratings unit supply voltage v + +9 v output pin current i o 50 ma power dissipation p d tvsp8 :320 mw operating temperature range t opr -40 ~ +85 c storage temperature range t stg -40 ~ +125 c recommended operating conditions (ta=25c) parameter symbol min. typ. max. unit operating voltage v + 2.2 ? 8 v oscillator timing resistor r t 30 47 120 k ? oscillation frequency f osc 300 700 1,000 khz electrical characteristics (v + =3.3v, r t =47k ? , ta=25c) parameter symbol test condition min. typ. max. unit under voltage lockout block on threshold voltage v t_on v + = l h 1.9 2.0 2.1 v off threshold voltage v t_off v + = h l 1.8 1.9 2.0 v hysteresis voltage v hys 60 100 ? mv soft start block soft start time t ss v t_on duty=80% 8 16 24 ms short circuit protection block input threshold voltage v t_pc fb pin 0.95 1.00 1.05 v charge current i chg v scp =0v 1.5 2 2.5 a latch mode on threshold voltage v t_la scp pin 0.95 1.00 1.05 v latch mode off threshold voltage v t_laoff scp pin 0.2 0.45 0.7 v oscillator block rt pin voltage v rt -5% 0.5 +5% v oscillation frequency f osc 630 700 770 khz oscillate supply voltage fluctuations f dv v + =2.2v ~ 8v ? 1 ? % oscillate temperature fluctuations f dt ta = - 4 0 c ~ +85 c ? 3 ? %
NJU7631 - 4 - ver.2006-07-12 electrical characteristics (v + =3.3v, r t =47k ? , ta=25c) parameter symbol test condition min. typ. max. unit error amplifier block reference voltage v b -1.0% 1.00 +1.0% v input bias current i b -0.1 ? 0.1 a open loop gain a v ? 80 ? db gain bandwidth product g b ? 1 ? mhz i om+_1 v fb =1v, v in- =0.9v 25 55 95 ma output source current i om+_2 v fb =1v, v in- =0.9v, v + =2.2v 4 9 16 ma output sink current i om- v fb =1v, v in- =1.1v 0.10 0.16 0.22 ma pwm comparate block v t_25 duty= pfmd uty 0.29 0.35 0.41 v input threshold voltage v t_50 duty=50% 0.44 0.5 0.56 v m ax d uty_1 v fb =0.9v 100 ? ? % maximum duty cycle m ax d uty_2 v fb =0.9v, r dtc =47k ? 40 50 60 % pwm/pfm change duty cycle pfmd uty 17 25 33 % output block output high level on resistance r oh i o =-20ma ? 10 20 ? output low level on resistance r ol i o =+20ma ? 5 10 ? general characteristics quiescent current i dd r l =non load ? 800 1200 a
NJU7631 - 5 - ver.2006-07-12 typical applications step-down converter scp v in v out c scp 1 fet sbd 2 3 4 5 6 7 8 r dtc c s in- fb v + dtc rt gnd out r t c out c in r2 r1 c nf r nf c l NJU7631
NJU7631 - 6 - ver.2006-07-12 typical characteristics 100 1000 10 100 oscillation frequency f osc (khz) oscillation frequency vs. timing resistance (v + =3.3v, ta=25 o c) timing resistance r t (k ? ) 660 680 700 720 740 0246810 oscillation frequency fosc (khz) operating voltage v + (v) oscillation frequency vs. operating voltage (r t =47k ? , ta=25 o c) 0 20 40 60 80 100 0 20406080100 duty cycle m ax d uty (%) dead time control resistance r dtc (k ? ) duty cycle vs. r dtc (v + =3.3v, r t =47k ? , ta=25 o c) 0.996 0.998 1 1.002 1.004 0246810 reference voltage v b (v) operating voltage v + (v) reference voltage vs. operating voltage (ta=25 o c) 0 200 400 600 800 1000 1200 1400 0246810 quiescent current i dd ( a) operating voltage v + (v) quiescent current vs. operating voltage (r t =47k ? , r l =non load, ta=25 o c)
NJU7631 -7- ver.2006-07-12 typical characteristics (v + =3.3v, gain=40db, ta=25 o c) 0 15 30 45 60 0 45 90 135 180 0.1 1 10 100 1000 10000 error amplifier block voltage gain, phase vs. frequency phase (deg) frequency f (khz) voltage gain av (db) phase gain 0 2 4 6 8 10 12 14 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) output high level on resistance r oh ( ? ) output block output high level on resistance vs. temperature (io=-20ma) v + =3.3v v + =1.95v v + =8v 0 2 4 6 8 10 12 14 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) output low level on resistance r ol ( ? ) output block output low level on resistance vs. temperature (io=+20ma) v + =3.3v v + =1.95v v + =8v 1 10 100 1000 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) output source current i om+ (ma) error amplifier block output source current vs. temperature (v fb =1v, v in- =0.9v) v + =3.3v v + =1.95v v + =8v 0 0.05 0.1 0.15 0.2 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) output sink current i om- (ma) error amplifier block output sink current vs. temperature (v fb =1v, v in- =1.1v) v + =1.95v, 3.3v, 8v
NJU7631 - 8 - ver.2006-07-12 typical characteristics 8 10 12 14 16 18 20 22 24 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) soft start time tss (ms) soft start time vs. temperature (v + =3.3v) 0.99 0.995 1 1.005 1.01 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) reference voltage v b (v) reference voltage vs. temperature (v + =3.3v) 640 660 680 700 720 740 760 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) oscillator frequency f osc (khz) oscillator frequency vs. temperature (v + =3.3v, r t =47k ? ) 1.86 1.9 1.94 1.98 2.02 2.06 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) threshold voltage (v) under voltage lockout block vs. temperature v t_off v t_on 0 200 400 600 800 1000 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) quiescent current i dd ( a) quiescent current vs. temperature (v + =3.3v, r t =47k ? )
NJU7631 - 9 - ver.2006-07-12 memo [caution] the specifications on this databook are only given for information , without any guarantee as regards either mistakes or omissions. the application circuits in this databook are described only to show representative usages of the product and not intended for the guarantee or permission of any right including the industrial rights.
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