NJU7678 - 1 - ver.2010-10-26 internal 60v, 3a mosfet step-up / flyback switching regulator ic general description package outline features drain to source voltage 60v max. drain to source current 3a max. pwm switching control operating voltage range 2.5v to 7.0v oscillating frequency range 300khz to 1mhz maximum duty cycle 90% typ. soft-start function internal fixed value: 4ms typ. or adjustable by external part dead time control timer latch for short circuit protection package outline NJU7678mlk: eqfn24 pin configuration (*1): exposed pad connected to internal fet drain NJU7678 is step-up/fly back type switching regulator ic with pwm control. 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 for design flexibility. NJU7678mlk bottom view (top view) (bottom view) NJU7678mlk pin function 1. fb 13. n.c. 2. in- 14. source 3. n.c. 15. source 4. scp 16. source 5. n.c. 17. source 6. dtc 18. n.c. 7. n.c. 19. drain 8. rt 20. drain 9. n.c. 21. drain 10. gnd 22. n.c. 11. n.c. 23. v + 12. n.c. 24. n.c. 1 2 3 4 5 6 18 17 16 15 14 13 7 8 9 10 11 12 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 pad (*1)
NJU7678 - 2 - ver.2010-10-26 block diagram buffer 0.6v 0.5v osc 1v 0.5 r t a 2k ? 2 a uvlo soft start vref 1v 1v 0.65v 0.15v gnd rt dtc scp in- fb v + pwm scp er ? the initial soft start time is 4msec. the soft star t time can be adjusted by connecting the capacitor with the dtc pin. the charging current is calculated by 0.5/r t . the maxduty is 90%@700khz. maxduty can be adjusted by connecting resistance with the dtc pin. maxduty is calculated by (r dtc / r t ) 86 - 24. the short-circuit protection circuit is a timer latch type. the protection delay time can be adjusted with the capacitor connected with the scp pin. to releas e the latch mode, it should do reclosing the power supply (below the uvlo det ection voltage) or the scp pin down to gnd level.
NJU7678 - 3 - ver.2010-10-26 absolute maximum ratings (ta=25c) parameter symbol maximum ratings unit supply voltage v + +8 v drain to source voltage v ds 66 v drain to source current i ds 3 a power dissipation p d 660 (*2) 1,400 (*3) mw operating temperature range t opr -40 ~ +85 c storage temperature range t stg -40 ~ +125 c (*2): mounted on glass epoxy board based on eia/jedec. (101.5 114.5 1.6mm: 2 layers fr-4) (*3): mounted on glass epoxy board. (101.5 114.5 1.6mm: 4 layers fr-4, copper area 99.5 99.5mm) recommended operating conditions parameter symbol min. typ. max. unit operating voltage v + 2.5 ? 7 v drain to source voltage v ds ? ? 60 v oscillator timing resistor r t 30 47 120 k ? oscillation frequency f osc 300 700 1,000 khz package thermal resistance parameter symbol thermal resistance unit junction-to- ambient temperature ja 152 (*2) 71 (*3) c/w junction-to-case jt 15.1 (*2) 9.7 (*3) c/w (*2): mounted on glass epoxy board based on eia/jedec. (101.5 114.5 1.6mm: 2 layers fr-4) (*3): mounted on glass epoxy board. (101.5 114.5 1.6mm: 4 layers fr-4, copper area 99.5 99.5mm)
NJU7678 - 4 - ver.2010-10-26 electrical characteristics (v + =3.3v, r t =47k ? , ta=25 c) parameter symbol test condi tion min. typ. max. unit under voltage lockout block on threshold voltage v t_on v + = l h 1.6 1.7 1.8 v off threshold voltage v t_off v + = h l 1.5 1.6 1.7 v hysteresis voltage v hys 60 100 ? mv soft start block soft start time t ss v t_on duty=80% 2 4 8 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 0.90 1.00 1.10 v latch mode off threshold voltage v t_laoff scp pin 0.35 0.6 0.85 v oscillator block rt pin voltage v rt -8% 0.5 +8% v oscillation frequency f osc 630 700 770 khz oscillate supply voltage fluctuations f dv v + =2.5v to 7v ? 1 ? % oscillate temperature fluctuations f dt ta = - 4 0 c to +85 c ? 3 ? % 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 output source current i om+ v fb =1v, v in- =0.9v 20 35 50 a output sink current i om- v fb =1v, v in- =1.1v 1.0 4.0 12 ma pwm comparator block v t_0 duty=0% 0.10 0.16 0.22 v input threshold voltage v t_50 duty=50% 0.36 0.42 0.48 v m ax d uty_1 v fb =0.9v 85 90 95 % maximum duty cycle m ax d uty_2 v fb =0.9v, r dtc =43k ? 45 55 65 % output block r ds(on) i o =3a ? 0.060 0.080 ? drain to source on resistance r ds(on)_2.5 i o =3a, v + =2.5v ? 0.065 0.085 ? drain to source leak current i ds_leak v ds =60v, v in- =1.1v ? ? 0.1 a general characteristic quiescent current i dd v in- =1.1v, v fb =0.5v ? 6.5 7.5 ma
NJU7678 - 5 - ver.2010-10-26 typical applications < step-up circuit > v + v c in r2 sbd r1 c out l scp in- fb v + dtc rt source NJU7678 c scp c nf r nf r dtc c r t gnd drain c dtc < fly back circuit > v + v out c in r2 sbd r1 c out t scp in- fb v + dtc rt source NJU7678 c scp c nf r nf r dtc c r t gnd drain c dtc
NJU7678 - 6 - ver.2010-10-26 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 ? ) 80 85 90 95 100 100 1000 maximum duty cycle m ax d uty_1 (%) maximum duty cycle vs. oscillator frequency (v + =3.3v, ta=25 o c) oscillator frequency f osc (khz) 660 680 700 720 740 02468 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) 0.99 0.995 1 1.005 1.01 02468 reference voltage v b (v) operating voltage v + (v) reference voltage vs. operating voltage (ta=25 o c) 0 2 4 6 8 10 12 14 16 02468 quiescent current i dd (ma) operating voltage v + (v) quiescent current vs. operating voltage (r t =47k ? , v in- =1.1v, v fb =0.5v, ta=25 o c)
NJU7678 - 7 - ver.2010-10-26 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 0.02 0.04 0.06 0.08 0.1 0.12 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) drain - source on resistance r ds(on) ( ? ) drain - source on resistance vs. temperature (io=3a) v + =2.5v v + =3.3v v + =7v 0 0.2 0.4 0.6 0.8 1 -50-250 255075100125 ambient temperature ta ( o c) drain - source leak current i ds_leak ( a) drain - source leak current vs. temperature (v ds =60v, v in- =1.1v)
NJU7678 - 8 - ver.2010-10-26 typical characteristics 2 3 4 5 6 7 8 -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 ? ) 40 50 60 70 80 90 100 -50 -25 0 25 50 75 100 125 ambient temperature ta ( o c) muximum duty cycle m ax d uty (%) muximum duty cycle vs. temperature (v + =3.3v) m ax d uty_1 m ax d uty_2 1.5 1.55 1.6 1.65 1.7 1.75 1.8 -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 5 5.5 6 6.5 7 7.5 8 -50-250 255075100125 ambient temperature ta ( o c) quiescent current i dd (ma) quiescent current vs. temperature (v + =3.3v, r t =47k ? , v in- =1.1v, v fb =0.5v)
NJU7678 - 9 - ver.2010-10-26 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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