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datashee t product structure silicon monolithic integrated circuit this product is not designed for pr otection against radioactive rays . 1/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 tsz22111 ? 14 ? 001 www.rohm.com 1.5a led camera flash driver synchronous rectification step-up dc/dc BD7757MWX general description the BD7757MWX is a 1.5a flash led driver with synchronous rectification step up dc/dc converter that can drive 1led. the led current, timer, and uvlo threshold can be varied by using upic++ (uni-port interface control ++). features synchronous rectification step-up dc/dc converter. control of registers via un i-port interface control ++ (upic) maximum current of 1.5a in flash mode (low side led driver). lighting mode setup flash mode?1.5a (max) torch mode?450ma (max) variable led current protection circuit: over current protection circuit (ocp) over voltage protection circuit (ovp) vout ? gnd short protection circuit led short / open protection circuit under voltage lock out circuit (uvlo) thermal shut down circuit (tsd) battery drop protection circuit flash timer protection circuit applications flash led driver for camera and smart phone dsc, dvc video lighting for digital video applications amusement accessory key specifications ? input voltage range : 2.7v to 5.0v ? led current (flash): 1.5a (max) ? led current (torch): 450ma (max) ? switching frequency : 2mhz (typ) ? pch fet on resistance : 150m ? (typ) ? nch fet on resistance : 100m ? (typ) ? standby current at shut down : 0 a (typ) ? operating temperature range: -30 to +85 package w(typ.) x d(typ.) x h(max.) uson014x3020 3.00mm x 2.00mm x 0.60mm pin configuration typical application circuit figure 1. application circuit figure 2. pin configuration
datasheet d a t a s h e e t 2/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX pin description terminal no. pin name in/ out esd diode function for power for gnd 1 agnd - - - ground 2 control1 in - gnd upic++ control input 3 fl out - gnd flash/torch current output 4 control2 in - gnd flash on/off terminal. (compulsive lighting, even if control1=low state. output flash current set with initial state at control1=low state.) 5 agnd - - - ground 6 in in - gnd power supply 7 pgnd - - - power ground 8 out out - gnd dcdc output voltage 9 nc - - - no connection 10 sw in - gnd switching output 11 control3 in - gnd flash on/off terminal. (compulsive lighting, even if control1=low state. output flash current set with initial state at control1=low state.) 12 nc - - - no connection 13 pgnd - - - power ground 14 rset out - gnd the resistor connection terminal of output led current setting. block diagram figure 3. block diagram
datasheet d a t a s h e e t 3/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX absolute maximum ratings paramete r symbol limit unit input voltage [all terminal] v max 7 v power dissipation pd 1.75 (*1) w operating temperature range topr -30 to +85 o c storage temperature tstg -55 to +150 o c *1 derate by 14mw/c when operating above 25c (mount on 2-layer board) recommended operating conditions paramete r symbol limit unit supply voltage v in 2.7 to 5.0 v maximum output current in flash mode i fled _ max 1.5 a maximum output current in torch mode i tled _ max 450 ma electrical characteristics (unless otherwise specified, ta = +25 o c, v bat =3.6v) parameter symbol min. typ. max. unit conditions logic controller low threshold voltage v il -0.3 - 0.4 v control1,2,3 high threshold voltage v ih 1.4 - 5.2 v control1,2,3 controlx=high input current i fh - 36 70 a control1,2,3=3.6v controlx=low input current i fl -1 0 1 a control1,2,3=0v control1 high time t hi 1 - 100 s control1 low time t lo 1 - 100 s access available time t acc - - 500 s control1 off timeout t off - - 500 s latch time t lat - - 1 ms others quiescent current i q - 0.1 2.0 a current consumption i dd1 - 3.0 - ma i led =100ma sw nmos on resistance r onn - 0.10 - v in =3.6v, at 200ma sw pmos on resistance r onp - 0.15 - v out =3.6v at 200ma inductor current limit i coil - 3 - a this parameter is tested in dc measurement. switching frequency f sw 1.6 2 2.4 mhz duty cycle limit duty 50 80 - % v hr =0.0v output voltage range vo - - 5.1 v over voltage protection limit v ovp - 5.4 5.7 v v hr =0.0v led short threshold voltage v stv 1.5 1.7 1.9 v (v out -v fl ) =sweep up led test current during led short protect i tled 1 2 3 ma v fl =2v headroom voltage v hr 0.18 0.23 0.28 v at step up condition torch led current accuracy i t - diff -10 0 10 % i led =100ma flash led current accuracy i f - diff1 -10 0 10 % i led =1.0a uvlo cancel voltage v uvlo 2.4 2.5 2.6 v v in sweep up uvlo hysteresis voltage v uvlo_hys 0.2 0.3 0.4 v v in sweep down
datasheet d a t a s h e e t 4/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX typical performance curves figure 7. rset voltage [v] vs. in voltage [v] figure 4. efficiency [%] vs. in voltage [v] (flash mode) figure 5. efficiency [%] vs. in voltage [v] (torch mode) figure 6. circuit current [ma] vs. temperature [ ] 50 55 60 65 70 75 80 85 90 95 100 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 in voltage [v] effeciency [%] 50 55 60 65 70 75 80 85 90 95 100 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 in voltage [v] effeciency [%] flash1.5a (a2d1) flash1.0a (a2d11) flash0.75a (a2d16) torch=450ma (a3d1) torch=300ma (a3d6) torch=200ma (a3d9) torch=150ma (a3d11) 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 temp [ ] circuit curr ent [ma] rset=90k ifl=100ma vfl=0.6v torch mode in=2.7v in=3.6v in=5.0v 0 100 200 300 400 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 in voltage [v] rset voltage [mv] uvlo detect uvlo cancel rset=90kohm
datasheet d a t a s h e e t 5/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX typical performance curves - continued 90.0 92.0 94.0 96.0 98.0 100.0 102.0 104.0 106.0 108.0 110.0 -40-20 0 20406080 temperature [c] fl output current [ma] 0.90 0.92 0.94 0.96 0.98 1.00 1.02 1.04 1.06 1.08 1.10 -40-20 0 2040 6080 temperature [c] fl output curr ent [a] 1.6 1.8 2 2.2 2.4 -40.0 -20.0 0.0 20.0 40.0 60.0 80.0 temper atur e [c] sw frequency [m hz] 0 20 40 60 80 100 120 140 160 5.0 5.1 5.2 5.3 5.4 5.5 out voltag e [v] fl output cur rent [m a] vbat=3.6v rset=90kohm torch mode figure 8. fl output current [a] vs. out voltage [v] figure 10. fl output current [ma] vs. temperature [c] at torch 100ma vbat=3.6v out=3.6v rset=90kohm vbat=3.6v vfl=0.6v rset=90kohm torch mode figure 11. fl output current [a] vs. temperature [c] at flash 1.0a vbat=3.6v vfl=0.6v rset=90kohm flash mode ovp cancel ovp detect figure 9. sw frequency [mhz] vs. temperature [c]
datasheet d a t a s h e e t 6/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX (n 18, nop) (n 29, nop) * initial data = 1 poff?stop led and dcdc output. finh?mode changes to torch mode correspondingly aux?flash mode turns on compulsorily with initial data (data=1) * initial data = 1 functional description 1. maximum flash current setup the maximum flash current can be set by varying the va lue of rset which is connected to rset-gnd terminal. the resistor value can be calculated using the equation: flash current = 1-1 maximum flash current setup rset flash current 60 k iled = 1.5a 75 k iled = 1.2a 90 k iled = 1.0a if rset is set less than 36k ? (typ.), the led current is stopped by internal iset short limit circuit. 2. register control flash-to-torch ratio can be controlled by the 16-data register. the on/ off control of led current, the flash timer, the led current threshold at timer start and the low battery detect can also be set through the register. register map is as follows; (n: number of edges) 2-1 address map (initial address = 1) n address addressed register data initial data 1 1 select torch/flash mode. select inhibit/aux 1-3 4- 5 1 (poff) 2 2 flash current setting 1-16 1 (1.0a at rset=90k) 3 3 torch current setting 1-16 11 (100maat rset=90k) 4 4 led timer setting 1-16 10 (1000ms) 5 5 led current threshold at timer start 1-8 6 (300ma) 6 6 low battery detection setting 1-10 10 (no detect) 2-2 address description n data symbol mode description 13 1 * poff power off 14 2 ton torch on 15 3 fon flash on 16 4 finh inhibit on 17 5 aux aux on n data fratio rset =60k ? rset =90k ? 13 1 * 100.0% 1500ma 1000ma 14 2 96.7% 1450ma 967ma 15 3 93.3% 1400ma 933ma 16 4 90.0% 1350ma 900ma 17 5 86.7% 1300ma 867ma 18 6 83.3% 1250ma 833ma 19 7 80.0% 1200ma 800ma 20 8 76.7% 1150ma 767ma 21 9 73.3% 1100ma 733ma 22 10 70.0% 1050ma 700ma 23 11 66.7% 1000ma 667ma 24 12 63.3% 950ma 633ma 25 13 60.0% 900ma 600ma 26 14 56.7% 850ma 567ma 27 15 53.3% 800ma 533ma 28 16 50.0% 750ma 500ma address 2, : flash current ratio address 1 : led mode flash current = maximum flash current fratio 1.0 a 90 k rset
datasheet d a t a s h e e t 7/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX (n 29, nop) * initial data = 11 (n 23, nop) * initial data = 10 (n 29, nop) * initial data = 10 (n 21, nop) * initial data = 3 functional description ? continued n data tratio rset =60k ? rset =90k ? 13 1 100.0% 450ma 300ma 14 2 93.3% 420ma 280ma 15 3 86.7% 390ma 260ma 16 4 80.0% 360ma 240ma 17 5 73.3% 330ma 220ma 18 6 66.7% 300ma 200ma 19 7 60.0% 270ma 180ma 20 8 53.3% 240ma 160ma 21 9 46.7% 210ma 140ma 22 10 40.0% 180ma 120ma 23 11 * 33.3% 150ma 100ma 24 12 26.7% 120ma 80ma 25 13 20.0% 90ma 60ma 26 14 13.3% 60ma 40ma 27 15 6.7% 30ma 20ma 28 16 0% 0.0ma 0.0ma n data flash timer 13 1 20ms 14 2 40ms 15 3 60ms 16 4 80ms 17 5 100ms 18 6 200ms 19 7 400ms 20 8 600ms 21 9 800ms 22 10 * 1000ms 23 11 1200ms 24 12 1400ms 25 13 1600ms 26 14 1800ms 27 15 2000ms 28 16 timer off n data led current threshold at timer start 13 1 400ma 14 2 350ma 15 3 * 300ma 16 4 250ma 17 5 200ma 18 6 150ma 19 7 100ma 20 8 50ma n data battery voltage 13 1 3.8 14 2 3.7 15 3 3.6 16 4 3.5 17 5 3.4 18 6 3.3 19 7 3.2 20 8 3.0 21 9 2.8 22 10 * no detect address 4 : flash timer address 5 : led current threshold at timer start address 3 : torch current ratio torch current =maximum torch current tratio address 6 : low battery detection
datasheet d a t a s h e e t 8/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX functional description ? continued 3. register access control protocol led current is controlled through the cont rol1 terminal whose input is from the uni -port interface. the register can be accessed by using the protocol below. (the first rising edge to control1 from the time of shutdown is not included in address and data assignment.) address / data selection waveform example address = 3 ? data = 8 (changes flash current to 53.3%) . after the uvlo circuit is triggered, all register settings are reset. hence, the regi sters has to be set again once uvlo circui t is cancelled (vbat>2.5v) *. *please refer to ?electrical characteristics? on p.3 for the specification on each symbol. item min max high input time ( t hi ) 1us 100us low input time ( t lo ) 1us 100us start a ddress t lat 3 edges data 3 1 8 1 address n = 20, data = 8 t lat 20 edges 1 2 17 18 19 20 register applies t acc this edge is not counted for ?n?. n= figure 13. control1 signal timing diagram figure 14. example of control1 signal t hi t lo control1
datasheet d a t a s h e e t 9/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX 4. startup and shut down sequence example of flash action using control1. 1. after power up of in terminal, input signal to control1. 2. if none of the protection circuit is enabled, vout starts charging after sending the flash or torch lighting signal. 3. test current (2ma, typ.) is loaded from fl current when it reaches vout>vin-0.25v. at that time, output fl current, if stv is not detected yet, soft start (ss:ic built-in circuit) starts to charger.. 4. dcdc completes boost up and led current is stable. 5. setting control1=l turns off the ic after t off time. figure 15. startup and shut down sequence using control1 1 2 3 4 5
datasheet d a t a s h e e t 10/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX shutdown act(flash on by control2,3) vout/fl ss(internal ic) ifl control2,3 control1 output ic state shutdown vin sw fl out uvlo/low bat uvlo/ovp/rset short/scp no detect condition vin-0.25v stv no detection initial setting t off flash action using control2 or control3 1. after power up of in terminal, input signal to control1 and next input control2 or control3. set condition by control1, before input control2 or control3. 2. if none of the protection circuit is enabled, vout starts charging. 3. test current (2ma, typ.) is loaded from fl current when it reaches vout>vin-0.25v. at that time, output fl current, if stv is not detected yet, soft start (ss:ic built-in circuit) starts to charger.. 4. dcdc completes boost up and led current is stable. 5. setting control2,3=l tu rns off the ic after t off time *startup in flash operation by control2 or 3=h and c ontrol1=low state, control1 cannot receive signal. therefore, when setting change is assumed dur ing the compulsive flash operation by contro l2 or 3, first of all, please input anything signal into control1 ( for keeping control1=h state). and control1 becomes possible receiving the signal also during the compulsive flash operation by setting control2 or 3=high state. figure 16. startup and shut down sequence using control2 or control3 1 2 3 4 5
datasheet d a t a s h e e t 11/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX 5. flash or torch mode selection switching between flash and torch mode can be done using control1, 2 or 3 control terminal name input signal function control1 a1/d1 led/dcdc=off a1/d2 torch mode a1/d3 flash mode a1/d4 forcibly changes to torch mode (finh) a1/d5 flash turn on forcibly with initial data (aux) control2* high forced flash lighting (output in address/data assigned current) forced flash even when control1=low state control3* high forced flash lighting (output in address/data assigned current) forced flash even when control1=low state control2,3 are the same function priority number of flash/torch selection priority 1 priority 2 priority 3 priority 4 control1 a1/d4 (finh) compulsive torch operation control2 compulsive flash operation control1 a1/d5 (aux) compulsive flash operation with initial condition data control1 a1/d2 (torch operation) control3 compulsive flash operation control1 a1/d3 (flash operation) for example, when specifying a1/d4 by control1 and switching to torch mode, torch state is continued even if control3=high
datasheet d a t a s h e e t 12/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX 6. regarding led output current flash control when the setting changes to flash mode, the maxi mum output current can be set up to 1.5a the control method for setting flash mode control terminal name input signal control function control1 a1/d3 flash mode a1/d5 flash turn on forcibly with initial data (aux) control2 high forced flash lighting (output in address/data assigned current) forced flash even when control1=low state control3 high forced flash lighting (output in address/data assigned current) forced flash even when control1=low state if the setting continues to send high current to the led for an extended period of time, it will generate heat to the ic and wi ll cause lower luminance. in order to prevent this, flash timer function is built in and that time can be changed by setting the register (typ 1.0s). please refer to the maximum led current spec ification (p.6) and set up led timer (p.7). led timer function by setting the register, BD7757MWX can change the led curr ent threshold at timer start and the led timer. timer operation is applicable in both flash and torch mode. when the light on the led?s turn off because the timer finished, the following sequences are required in order to make the light re-switch back on. ? re-lighting by control1 1. input address=1/data=1 -> turn off led/ dcdc operation. -> input re-lighting signal. 2. control1= low during toff -> input re-start signal ? re-lighting by control2 or control3 1. control2 or control3=low -> input control2 or control3=low high. led current threshold at timer start this setting can be set by register 5 50ma~400ma (initial setting=300ma) ? led timer this setting can be set by register 4 20ms~2000ms no timer can also be selected (initial setting=1000ms) figure 17. timer operation 1
datasheet d a t a s h e e t 13/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX control2 or 3 ifl flash 0a timmer timer count control2 or 3 ifl 0a timmer timer count counter is reset when led current crosses the threshold during a timer count. while, when led current goes over the led current threshold,it counts back from the start. moreover, counter is reset when led current is set to turn off by control1,2 or 3 during a count. forced flash (control2,3) flash is turned on forcibly by sending a high signal to cont rol2 or control3(control2 an d control3 are of the same function). during flash mode, led?s can be turned off by control2 or control3 by ? control2 or control3=low ? timer end the sequence of flash operation by control2 or control 3 is shown below. led current threshold at timer start torch ? control2,3=on ? control2,3=off off ? control2,3=on ? control2,3=off torch ? control2,3=on ? timer end ? control2,3=off off ? control2,3=on ? timer end ? control2,3=off figure 18. timer operation 2 figure 19. led current operation by control2, 3
datasheet d a t a s h e e t 14/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX control1 torch a1/d2 ifl a1/d1 control2,3 control1 torch a1/d4 ifl tacc forced torch (finh) setting address=1 and data=4 through control1, led current will enter torch mode correspondingly this mode has the highest priority, and makes the light swit ch on in torch mode even in lighting state at all times. therefore, even if the mode is set flash mode by control2 or 3, the output remains at torch mode. startup in compulsive flash operation by control2 or 3=h and control1=low state, control1 cannot receive signal while control2 or 3=h. therefore, when finh setting is assumed during th e compulsive flash operation by control2 or 3, first of all, please input anything signal into control1 ( for keeping cont rol1=h state). and control1 becomes possible receiving the finh signal also during the compulsive flash oper ation by setting control2 or 3=high state. torch mode to go to torch mode, control1 sets data=2 in address 1. torch current can be set by 0% to 100% with 16steps. in addition, sending address=1 and data=4 throu gh control1, ic goes to torch mode forcibly (please refer to [forced torch]) compulsorily torch on flash on forced torch on flash on flash current does not flow for forced torch mode. torch on off figure 20. led current operation by finh (a1/d4) figure 21. led current operation (torch mode)
datasheet d a t a s h e e t 15/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX 7. protect function failure mode detection mode led current dcdc action after release failure register state condition for releasing latch led open ovp detect stop stop auto return keep - led short led short detect stop stop latch keep reset by control1,2,3 or uvlo rset short iset short detect stop stop auto return keep - cout short output short detect stop stop auto return keep - high temperature tsd detect stop stop latch reset reset by control1 or uvlo low battery uvlo detect stop stop auto return reset - low battery low battery detect stop stop auto return keep - over voltage protection (ovp) / led open protection (lop) whenever the led is not connected to fl or out terminal , fl terminal voltage becomes low. therefore, dc/dc voltage will increase drastically and the vout terminal voltage will detect ovp. then, led and dcdc driver will stop and output voltage will decrease by discharging. when the output volta ge reaches under the ovp hysteresis, dcdc will boost up again and will detect ovp. the over voltage during le d open mode is protected by this operation. output short protection when out pin voltage becomes 1.0v or less, the dcdc/led driver stops and flowing of large current can be prevented in breakdown caused by short mode of output capacitance. this ti me, constant current of 100ma from out pin is sourced. this returns to normal, if short mode is released. led short protection at start up timing, vout is charged until vout=vin state, and led / dcdc driver starts operat ing. a test current (2ma typ.) flows from fl terminal before it supplies the led current. led is short at this time, if the voltage between fl-out pins becomes 1.7v or less, then it becomes la tch stop. to release the latch, in t he case of lighting by control1, input control1=low or poff (address 1 / data1). in the case of lighting bycontrol2 or 3, set control2 or 3 to low thermal shutdown if the chip temperature amounts to 155c or more, thermal s hutdown circuit will be enabled and latched. to release the latch, in the case of lighting by control1, input control1 =low or poff (address 1 / data1). in the case of lighting bycontrol2 or 3, set control2 or 3 to low. under voltage lock out (uvlo) if the vin voltage decreases under 2.2v, uvlo circuit wi ll be enabled. only when vin voltage increases over 2.5v will uvlo be cancelled. when the uvlo circuit is enabled, a ll the systems and register setup will also be reset. low battery uvlo low battery uvlo can set the threshold from 2.8v to 3.8v using the register. in addition, it can be set to no detect mode. the registers are not reset when the protec tion circuit is triggered. when in voltage increases to more than the hysteresis level (0.1v typ.), it will re-start. figure 22. ovp and lop operation
datasheet d a t a s h e e t 16/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX application circuit it is recommended to connect the r_rset resistance, which sets up the led current between pin14:rset and pin1:agnd. moreover, do not connect pin1 to gnd of the dut board. (pin1 agnd an d pin5 agnd is shorted inside the ic) selection of components externally connected parts name symbol value unit product number min typ max input capacitor cin 1.0 2.2 - f murata : grm188b31a225ke33 inductor l - 1.0 - h tdk : vlf403210mt-1r0n output capacitor cout 1.8 4.7 - f murata : grm188b30j475ke18 led current setting resistor r_rset 60 - 120 k ? (60k ? ) rohm : mcr006yzpd1203 //2 inductor as an important characteristic of an inductor, it increases t he allowable current and serial resistive components. the step up ratio is high. thus, when the output led current is high, t he current which flows into the inductor becomes very high. therefore, it is necessary to select an inductor with high maximum allowable current. moreover, efficiency is affected by the series resistance components. therefore, it is recommended that there is a margin to the maximum allowable current. selecting the inductor with a small series resistance value is also suggested. ? inductor current calculation the current which flows into the inductor is determined by the following conditions: output voltage=vout [v] led current=iled [a] input voltage=vin [v] pmos onr=ponr[ ? ] feed back voltage=vfb[v] inductor series resistance value=rl[ ? ] efficiency= [%] the average current needed for the applicat ion is called for using the formula. in the driver operation with dcdc switching frequency=fsw[hz], the ripple current S il[a] which occurs in in ductor l [h] is described by the formula: therefore, the peak current of the inductor becomes, (1) formula of the inductor current at dcdc operation. t he inductor current dcdc stops, becomes the current running through the led. [%] ] v [ vin ] a [ iled ) iled ] [ rl vfb iled ponr ] v [ vout ( ] a [ iin ? ? ? ? ? ? ? ? ? ? ] a [ ] hz [ f ] v [ v ] h [ l ] v [ v ]) v [ v ] v [ v ( il sw out in in out ? ? ? ? ? ) 1 ( ] [ 2 ] [ ] [ ? a a il a i ipeak in ? ? ? figure 23. application circuit figure 24. inductor current
datasheet d a t a s h e e t 17/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX ? example computation output voltage=4v led current=1.0 [a] input voltage=3.6 [v] efficiency=85 [%] l=1.0[ h] freq=2[mhz] pmos onr=0.15[ ] feed back voltage=0.23[v] inductor series resistor value=0.05[ ? ] the peak current of the inductor in this condition is computed. input /output capacitor high current is charged and discharged to the input / output capacitor at that time of dcdc switching oper ation. therefore, if a capacitor of high esr is used, ripple will occur and efficiency will get worse. it is recommended to use a ceramic capacitor of small esr. resistor for led current led current is set by the resistor which is connecting r set and agnd terminal. since the temperature characteristics and variation of the resistance influences the led current dire ctly, it is recommend to use a resistance of low temperature characteristics and variation. ] a [ 17 . 1 [%] 85 ] v [ 6 . 3 ] a [ 0 . 1 ]) a [ 0 . 1 ] [ 05 . 0 ] v [ 23 . 0 ] a [ 0 . 1 ] [ 15 . 0 ] v [ 4 ( ] a [ iin ? ? ? ? ? ? ? ? ? ? ? ] a [ 18 . 0 ] hz [ e 2 ] v [ 0 . 4 ] h [ e 0 . 1 ] v [ 6 . 3 ]) v [ 6 . 3 ] v [ 0 . 4 ( il 6 6 ? ? ? ? ? ? ? ] a [ 26 . 1 2 ] a [ 18 . 0 ] a [ 17 . 1 ipeak ? ? ?
datasheet d a t a s h e e t 18/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX power dissipation 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 0 25 50 75 100 125 150 temper atur e [ ] power dissipation [w ] figure 25. power dissipation [w] vs. temperature [ ] board material: grass epoxy layer: 2 layers pd=1.75w at 25
datasheet d a t a s h e e t 19/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX i/o equivalent circuits 2.control1 / 4.control2 / 11.control3 1.agnd / 5.agnd / 6.in / 7.pgnd 8.out / 10.sw / 13.pgnd 3.fl r14.set
datasheet d a t a s h e e t 20/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX notice for pcb layout since high current flows into the dut during flash lighting, the ground voltage is changed by the very small impedance of the pcb pattern. moreover, pcb layout is very important because it changes with pcb patterns. the voltage drop across the pattern also affects the efficiency and ripple. power gnd wire ?a? line is power gnd wire. high current flows through this wi re from 7pin-pgnd and 13pin-pg nd. therefore, by wiring it shortly and as thickly as possible, the potential differ ence across the wiring will not affect the operation. please short the patterns of the following pin directly 5pin: agnd, 7pin: pgnd, 13pin: pgnd. addition of a heat sink to this gnd pattern is also recommende d. the heat dissipation of ic is high thus wiring area has to be large. led wire the led current flows through the ?b? line. since a high current (l ed maximum current is 1.5a ) flows into this line, it is necessary to make it as thick as possible. the impe dance across the line will cause a decrease in efficiency. dcdc wire ?c? line is a course which the current passes through the i nductor. since the high current of led current and dcdc step-up current flows into this line, it is nec essary to make it as thick as possible. the impedance across the line will cause a decrease in efficiency. analog wire ?d? line is an analog line. since high current does not flow into this wiring, it is acceptable to use thin wiring. however, si nce rset terminal is very weak to a switching noise, precautions must be taken to avoid crosstalk with sw terminal. as a recommendation, r_rset has to be placed immediately n ear the terminal. by shortening distance between resistance r_rset and rset terminal (about under 5mm), crosstalk can be avoided. regarding capacitor output capacitor has to be placed near the out terminal and connect gnd to power gnd. input capacitor has to be place near the inductor and connect gnd to power gnd. if the wiring impedance against the capacitance serially attac hes, it becomes ripple factors of vin voltage and out voltage. it also causes a decrease in efficiency. the example of a layout of rohm evaluation board (2 layers) is shown as reference below. 1st layer 2nd layer silk figure 26. application circuit for pcb figure 27. example of pcb a b b c d d d
datasheet d a t a s h e e t 21/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX operational notes 1. reverse connection of power supply 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 s upply lines of the digital bloc k from affecting the analog block. furthermore, connect a capacitor to ground at all po wer 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 t he 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 refe rence point of the application board to avoid fluctuations in the small-signal ground caused by large currents. also ensure that the ground trac es 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 exceed ed the rise in temperature of the chip may result in deterioration of the properties of the ch ip. the absolute maximum rating of the pd stated in this specification is when the ic is mounted on a 70mm x 70mm x 1.6mm glass epoxy b oard. 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 expect ed characteristics of the ic can be approximately obtained. the electrical characteristics are guarantee d 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 s pecial consideration to power coupling capacitance, power wiring, width of ground wiri ng, 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 may subject the ic to stress. always dischar ge 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 assemb ly 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 pc b. incorrect mounting may result in damaging the ic. avoid nearby pins being shorted to each ot her especially to ground, power supply and output pin. inter-pin shorts could be due to many reasons such as me tal particles, water droplets (in very humid environment) and unintentional solder bridge deposited in between pins during assembly to name a few.
datasheet d a t a s h e e t 22/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX operational notes ? continued 11. unused input pins input pins of an ic are of ten connected to the gate of a mos transistor. the gate has extremely high impedance and extremely low capacitance. if left unc onnected, the electric field from th e outside can easily charge it. the small charge acquired in this way is enough to produce a signifi cant 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+ isolat ion and p substrate layers between adjac ent elements in order to keep them isolated. p-n junctions are formed at the intersection of t he 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 dam age. therefore, conditions that cause these diodes to operate, such as applying a voltage lower than the gnd voltage to an input pin (a nd thus to the p substrate) should be avoided. figure 28. example of monolithic ic structure 13. ceramic capacitor when using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with temperature and the decrease in nominal capacitance due to dc bias and others. 14. area of safe operation (aso) operate the ic such that th e output voltage, output current, and power dissipation are all within the area of safe operation (aso). 15. thermal shutdown circuit(tsd) this ic has a built-in thermal shutdown circuit that pr events heat damage to the ic. normal operation should always be within the ic?s power dissipation rating. if however th e rating is exceeded for a continued period, the junction temperature (tj) will rise which will activate the tsd circuit that will turn off all output pins and latch. note that the tsd circuit operates in a situation that exceeds the absolute ma ximum ratings and therefore, under no circumstances, should the tsd circuit be used in a set desi gn or for any purpose other t han protecting the ic from heat damage. 16. over current protection circuit (ocp) this ic incorporates an integrated over current protection circuit that is acti vated when the load is shorted. this protection circuit is effective in pr eventing damage due to sudden and unexpecte d incidents. however, the ic should not be used in applications characterized by continuous operation or transitioning of the protection circuit.
datasheet d a t a s h e e t 23/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX ordering information b d 7 7 5 7 m w x - e 2 part number package mwx : uson014x3020 packaging and forming specification e2: embossed tape and reel physical dimension tape and reel information marking diagram uson014x3020 (top view) part number marking lot number 1pin mark 1234 5678
datasheet d a t a s h e e t 24/24 tsz02201-00f1fc200020-1-2 ? 2013 rohm co., ltd. all rights reserved. 03.dec.2014 rev.004 www.rohm.com tsz22111 ? 15 ? 001 BD7757MWX revision history date revision changes oct.25.2013 002 p14 / modify indication of finh data a1d5->a1d4 nov.07.2013 003 p3 p8 p9 p12 /modify symbol nov.07.2013 003 p3 /modify min limit of max duty nov.07.2013 003 p10 /modify the instruction of startup and shut down sequence nov.07.2013 003 p11 /delete the (data=1) comment in table nov.07.2013 003 p12 / delete the (data=1) comment in table nov.07.2013 003 p14 /modify the instruction of forced torch (finh) nov.07.2013 003 p15 /modify the instruction of led short pr otection, thermal shutdown, and battery uvlo nov.07.2013 003 p20 /modify the instruction of analog wire nov.07.2013 003 p21,22 /modify operation notes dec.03.2014 004 p2 /modify the instruction of control2 and control3 dec.03.2014 004 p10 /modify the instruction of flash action using control2 or control3 dec.03.2014 004 p16 /modify selection of components externally connected limit. dec.03.2014 004 p1 /modify operating temperature range
notice - p ga - e rev.00 3 ? 201 5 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. our p roducts are designed and manufactured for application in ordinary electronic equipment s ( such as av equipment, oa equipment, telecommunication equipment, home elec tronic appliances, amusement equipment, etc.). if you intend to use our products in devices requiring extremely high reliability ( such as medical equipment ( n ote 1 ) , transport equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, f uel 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 consult with the rohm sales represe ntative in advance. unless otherwise agreed in writing by rohm in advance, rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any rohm s products for specific appl ications. ( n ote1) m edical e quipment c lassification of the s pecific applications japan usa eu china class 2. rohm designs and manufactures its products subject to strict quality control system. however, semiconductor products can fail or malfunction at a certain rate. please be sure to implement, at your own responsi bilities, adequate 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 following are examples of safety measures: [a] installation of protection circuits or other protective devices to improve system safety [b] installation of redundant circuits to reduce the impact of single or multiple circuit failure 3. our p roducts are designed and manufactured for use under standard conditions a nd not under any special or extraordinary environments or conditions, as exemplified below . accordingly, rohm shall not be in any way responsible or liable for any damages, expenses or losses arising from the use of any rohms p roduct s 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 below), your independent v erification and confirmation of product performance, reliability, etc, pri or to use, must be necessary : [a] use of our products in any types of liquid, including water, oils, chemicals, and organic solvents [b] use of our products outdoors or in places where the p roducts are exposed to direct sunlight or dust [c] use of our prod ucts in places where the p roducts are exposed 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 p roducts are exposed to static electricity or electromagnetic waves [e] use of our products in p roximity to heat - producing components, plastic cords, or other flammable items [f] s ealing or coating our p roducts with resin or other coating materials [g] use of our products without cleaning residue of flux (even if you use no - clean type fluxes, cleanin g 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 p roducts in places subject to dew condensation 4 . the p roducts are not subject to radiation - proo f design . 5 . please verify and confirm characteristics of the final or mounted products in using the products. 6 . in particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied, confirmation of pe rformance characteristics after on - board mounting is strongly recommended. avoid applying power exceeding normal rated power; exceeding the power rating under steady - state loading condition may negatively affect product performance and reliability. 7 . de - rate power dissipation d epending on a mbient temperature . when used in sealed area, confirm that it is the use in the range that does not exceed the maximum junction 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 f ailure induced under devian t condition from what is defined in this document . precaution for mounting / circuit board design 1. when a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product performance and reliability. 2. in principle, the reflow soldering method must be used on a surface - mount products, the flow soldering method must be used on a through hole mount products. i f the flow soldering method is preferred on a surface - mount products , please consult with the roh m representative in advance. for details , please refer to rohm mounting specification
notice - p ga - e rev.00 3 ? 201 5 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 considerin g variations of the characteristics of the p roducts and external components, including transient characteristics, as well as static characteristics. 2. you agree that application notes, reference designs, and associated data and information contained in t his document are presented only as guidance for products use . therefore, in case you use such information, you are solely responsible for it and you must exercise your own independent verification and judgment in the use of such information contained in t his document. rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such information. precaution for electrostatic this p roduct is e lectrostatic sensitive product, which may be damaged due to e lectrostatic discharge. please take proper caution in your manufacturing process and stor age so that voltage exceeding the product s maximum rating will not be applied to p roducts. please take special care under dry condition (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 p roducts are stored in the places where : [a] the p roducts are exposed to sea winds or corrosive gases, including 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, solderability of products out of recommended storage time period may be degraded. it is strongly recommended to confirm solderability before using p roducts of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the correct direction, which is indicated on a carton with a symbol. otherwise bent leads may occur due to excess ive stress applied when dropping of a carton. 4. use p roducts within the specified time after opening a humidity barrier bag. baking is required before using p roducts of which storage time is exceeding the recommended storage time period . precaution for p roduct l abel a two - dimensional barcode printed on rohm p roduct s label is for rohm s internal use only . precaution for d isposition when disposing p roducts please dispose them properly using a n authorized industry waste company. precaution for foreign e xchange and foreign t rade act since concerned goods might be fallen under listed items of export control prescribed by foreign exchange and foreign trade act, please consult with rohm in case of export. precaution regarding intellectual property rights 1. all information an d data including but not limited to application example contained in this document is for reference only. rohm does not warrant that foregoing information or data will not infringe any intellectual property rights or any other rights of any third party reg arding such information or data. 2. rohm shall not have any obligations where the claims, actions or demands arising from the combination of the products with other articles such as components, circuits, systems or external equipment (including software). 3. no license, expressly or implied, is granted hereby under any intellectual property rights or other rights of rohm or any third parties with respect to the products or the information contained in this document. provided, however, that rohm will not assert it s intellectual property rights or other rights against you or your customers to the extent necessary to manufacture or sell products containing the products, subject to the terms and conditions herein. 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 disassemble d, converted, modified, reproduced or otherwise changed without prior written consent of rohm. 3. i n no event shall you use in any way whatso ever the products and the related technical information contained in the products or this document for any military purposes , including but not limited to, the development of mass - destruction weapons . 4. the proper names of companies or products described in this document are trademarks or registered trademarks of rohm, its affiliated companies or third parties.
datasheet datasheet notice ? we rev.001 ? 2015 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.
datasheet part number BD7757MWX package uson014x3020 unit quantity 4000 minimum package quantity 4000 packing type taping constitution materials list inquiry rohs yes BD7757MWX - web page distribution inventory

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