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1/16 single-chip tpe with built-in fet switching regulator series flexible step-downswitching regulators with built-in power mosfet BD9778F, bd9778hfp, bd9001f, bd9781hfp rcaflga_jlmrc r rca r f lga_ j l www.rohm.com ? 2010 rohm co., ltd. all rights reserved. no.10027ebt41 overviewfeatures 1) 2) 3) 4) 5) 6) 8) 9) 10) 11) 12)13) 14) 15) minimal external components wide input voltage range: 7 v to 35 v (BD9778F/hfp and bd9781hfp), 7 v to 48 v (bd9001f) built-in p-ch power mos fet output voltage setting enabled with external resistor: 1 to v in reference voltage accuracy: 2% wide operating temperature range: -40?c to +125?c (BD9778F/hfp and bd9781hfp), -40?c to +95?c (bd9001f) low dropout: 100% on duty cycle standby mode supply current: 0 a (typ.) (BD9778F/hfp and bd9781hfp), 4 a (typ.) (bd9001f) oscillation frequency variable with external resistor: 50 to 300 khz (bd9001f), 50 to 500 khz (BD9778F/hfp and bd9781hfp) external synchronization enabled (only on the bd9781hfp) soft start function : soft start time fixed to 5 ms (typ.)) built-in overcurrent protection circuit built-in thermal shutdown protection circuit high power hrp7 package mounted (bd9778hfp and bd9781hfp) compact sop8 package mounted (BD9778F and bd9001f) all fields of industrial equipment, such as flat tv , printer, dvd, car audio, car navigation, and communication such as etc, av, and oa. applicationsproduct lineup the flexible step-down switching regulator controller is a switching regulator controller designed with a high-withstand-voltag e built-in power mos fet, providing a free setting function of operating frequency with external resistor. this switching regulat or controller features a wide input voltage range (7 v to 35 v or 7 v to 48 v) and operating temperature range (-40?c to +125?c or -40?c to +95?c). furthermore, an external synchronization input pin (bd9781hfp) enables synchronous operation with external clock. BD9778F/hfp 2a 7v ~ 35v 50 ~ 500khz not provided provided - 40?c ~ +125?c sop8 / hrp7 output currentinput range oscillation frequency range external synchronization standby function operating temperature package bd9001f 2a 7v ~ 48v 50 ~ 300khz not provided provided - 40?c ~ +95?c sop8 bd9781hfp 4a 7v ~ 35v 50 ~ 500khz providedprovided - 40?c ~ +125?c hrp7 item dec.2015 - rev.c downloaded from: http:///
2/16 te chnical note absolute maximum ratings(t a = 25?c) recommended operating range electrical characteristics *1 should not exceed pd-value.*2 reduce by 44mw/c over 25c, when mounted on 2-layer pcb of 70 x 70 x 1.6 mm3. (pcb incorporates thermal via. copper foil area on the front side of pcb: 10.5 x 10.5 mm2. copper foil area on the reverse side of pcb: 70 x 70 mm2) *3 reduce by 5.52 mw/c over 25c, when mounted on 2-layer pcb of 70 x 70 x 1.6 mm3. output switch pin voltageoutput switch current BD9778F/hfp,bd9781hfp BD9778F/hfp,bd9781hfp BD9778F/hfp, bd9001f bd9001fbd9001f bd9781hfp hrp7sop8 power dissipation parameter symbol unit v en/sync, v en v rt, v fb, v inv a p d limits 5.5 0.69 v in 2 en/sync, en pin voltage v in v sw i sw 50 w t opr t stg t jmax - 40 ~ +95 - 40 ~ +125 - 55 ~ +150 ?c?c ?c power supplyvoltage operating temperature range v in 36 vv v *1 4 *1*2 *3 rt , fb, inv pin voltage storage temperature rangemaximum junction temperature 7 150 BD9778F/hfp 7 ~ 35 ~ 2 6 ~ 100 50 ~ 50040 ~ 800 parameter operating power supply voltageoutput switch current output voltage (on duty) oscillation frequency oscillation frequency set resistance bd9001f 7 ~ 48 ~ 2 6 ~ 100 50 ~ 300 100 ~ 800 bd9781hfp 7 ~ 35 ~ 4 6 ~ 100 50 ~ 50039 ~ 800 unit va % khz k? possible operating range BD9778F/hfp 5 ~ 35 parameter operating power supply voltage bd9001f 7 ~ 48 bd9781hfp 5 ~ 35 unit v BD9778F/hfp (unless otherwise specified, ta = -40?c to +125?c, v in =13.2 v, v en = 5 v) circuit current standby circuit currentreference voltage 2 reference voltage 1 [error amp block] reference voltage input regulation input bias current maximum fb voltage parameter limits typ. min. max. 0.96 - -- operating output current of overcurrent protection 2 - symbol i olimit i oleak v ref2 v ref1 v ref i q i stb r on i b v fbh v fbl i fbsink i fbsource t ss f osc v en i en f osc - 1 2.4 70 -- 82 - 0.8 - condition v en =5v v fb =v inv v fb =1.5v,v inv =1.5v v fb =1.5v,v inv =0.5v khz v in =5 ~ 35v v in =5 ~ 35v v inv =1.1v v inv =0.5v v inv =1.5v v in =35v,v en =0v v en =0v,ta=25?c i o =0a i sw =50ma * design assurance* design assurance output leak current [sw block] power mos fet on resistance minimum fb voltagefb sink current fb source currentsoft start time [oscillator block] oscillation frequencyfrequency input regulation [enable block] threshold voltagesink current - - 5.0 unit a a a v % ma ? a vv ma a ms r t =390k? v a % 1.00 3 0.53 4 0.5 - 2.5 120 0.05 5 102 1 1.7 13 0 0 - 3.0 1.04 0.98 v fb =v inv ,ta=25?c v 1.00 1.02 4.2 100.9 -- - - 170 0.10 - 122 - 2.6 50 30 - 0.5 * not designed to be radiation-resistant. www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
3/16 te chnical note bd9781hfp (unless otherwise specified, ta= - 40?c ~ +125?c,v in =13.2v,v en/sync =5v) parameter symbol i olimit i oleak v ref2 v ref1 v ref i q i stb r on i b v fbh v fbl i fbsink i fbsource t ss f osc v en/sync i en/sync f sync f osc condition unit a a v % ma ? a vv ma a ms khz v a khz % v en/sync =5v v en/sync =0v,ta=25oc f en/sync =150khz v fb =v inv v fb =1.5v,v inv =1.5v v fb =1.5v,v inv =0.5v r t =390k? v in =5 ~ 35v v in =5 ~ 35v v inv =1.1v v inv =0.5v v inv =1.5v v in =35v,v en/sync =0v i o =0a i sw =50ma * design assurance* design assurance [enable/synchronizing input block] threshold voltagesink current external synchronizing frequency limits typ. min. max. 0.97 -- 4 - - 1 2.4 70 -- 82 - 0.8 - - - - 5.0 1.00 3 0.5 8 0.5 - 2.5 120 0.05 5 102 1 1.7 35 150 0 - 3.0 1.03 vv fb =v inv ,ta=25oc 0.98 1.00 1.02 8 0.9 -- - - 170 0.10 - 122 - 2.6 90 - 30 a - 01 0 - 0.5 * not designed to be radiation-resistant. circuit current standby circuit currentreference voltage2 reference voltage1 [error amp block] reference voltage input regulation input bias current maximum fb voltage operating output current of overcurrent protection output leak current [sw block] power mos fet on resistance minimum fb voltagefb sink current fb source currentsoft start time [oscillator block] oscillation frequencyfrequency input regulation bd9001f (unless otherwise specified, ta= - 40?c ~ +95?c,v in =13.2v, v en =5v) [enable block] threshold voltagesink current circuit current standby circuit currentreference voltage 2 reference voltage 1 [error amp block] reference voltage input regulation input bias current maximum fb voltage parameter operating output current of overcurrent protection v en i en symbol i olimit v ref2 v ref1 v ref i q i stb r on i b v fbh v fbl i fbsink i fbsource ts s f osc f osc condition v a unit av v % ma ? a a vv ma ms a khz % v fb =v inv v fb =1.5v,v inv =1.5v v fb =1.5v,v inv =0.5v r t =390k? v in =7 ~ 48v v in =7 ~ 48v v en =5v v inv =1.1v v inv =0.5v v inv =1.5v i o =0a i sw =50ma * design assurance* design assurance [sw block] power mos fet on resistance minimum fb voltagefb sink current fb source currentsoft start time [oscillator block] oscillation frequencyfrequency input regulation 0.8 1.713 2.6 50 limits typ. min. max. 0.96 0.98 - -- 2.5 - - 1 2.4 70 -- 82 -- - 5.0 1.00 3 0.6 4 0.5 - 2.5 120 5 0.05 102 2 - 3.0 1.04 1.00 1.02 4.2 41 0 1.2 -- - - - 170 0.10 122 - - 0.5 * not designed to be radiation-resistant. v en =0v,ta=25?c v fb =v inv ,ta=25?c www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
4/16 te chnical note reference data fig.1 output reference voltage vs. ambient temprature (all series) fig.2 frequency vs. ambient temperature (all series) fig.3 standby current (bd9781hfp) fig.5 standby current (bd9001f) fig.6 circuit current (bd9781hfp) fig.8 circuit current (bd9001f) fig.9 on resistance v in =5v (bd9781hfp) fig.11 on resistancev in =13.2v (bd9781hfp) 0.980 0.985 0.990 0.995 1.000 1.005 1.010 1.015 1.020 -25 -50 0 25 50 75 100 ambient temperature : ta[ j ] reference voltage : v ref [v] 125 0 100 200 300 400 500 600 -25 -50 0 25 50 75 100 ambient temperature : ta[ j ] oscillating frequency : fosc[khz] 125 910k? 91k? 390k? 39k? 0 1 2 3 4 5 6 7 8 9 10 5 01 01 52 02 53 04 0 input voltage : v in [v] stand-by current : i stb [a] 35 125 j v cc =12v istb=0.14 a 25 j 125 j 25 j C40 j -40 j fig.7 circuit current (BD9778F/hfp) 10 5 01 0 1 5 2 02 5 3 04 0 input voltage : v in [v] circuit current : i cc [ma] circuit current : i cc [ma] 35 2 3 4 dpmkrfcrmn* - 40 j 25 j 125 j dpmkrfcrmn* - 40 j 25 j 125 j 10 5 01 0 1 52 02 53 04 0 input voltage : v in [v] circuit current : i cc [ma] stand-by current : i stb [a] 35 2 3 4 fig.10 on resistance v in =7v (bd9781hfp) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.5 0.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 output current : i o [a] fet on resistance : r on [?] t a=25 j ta = 1 25 j t a=-40 j 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.5 0.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 output current : i o [a] fet on resistance : r on [?] ta =25 j ta = 1 25 j ta =-40 j 4.5 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.5 0.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 output current : i o [a] fet on resistance : r on [?] ta = 2 5 j t a=125 j ta =-40 j fig.4 standby current (BD9778F/hfp) 5 01 01 52 02 53 04 0 35 input voltage : v in [v] input voltage : v in [v] input voltage : v in [v] 0 1 2 3 4 5 6 7 8 9 10 stand-by current : i stb [a] 125 j 25 j -40 j v cc =12 v istb=0.14 a 60 60 50 40 30 20 10 0 10 20 30 40 50 40 30 20 10 0 1 2 3 4 dpmkrfcrmn* 125 j - 40 j 25 j fig.12 on resistance v in =5v (BD9778F/hfp) output current : i o [a] 0.5 0.0 1.0 1.5 2.0 2.5 fet on resistance : r on [?] t a=-40 j ta =25 j ta = 125 j www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
5/16 te chnical note output current : i o [a] 10 20 30 40 50 60 70 80 90 100 0 00 . 51 . 0 conversion efficiency [%] 1.5 2.0 5v output 3.3v output fig.18 i o vs efficiency(v in =12v,f=100khz) y (BD9778F/hfp) 0 1 2 3 4 5 6 output voltage : v o [v] 1 02 3 4 5 output current : i o [a] ta = 2 5 j t a=125 j ta =-40 j fig.21 current capacitance(v in =12v,vo=5v,f=100khz) (BD9778F/hfp) 0 1 2 3 4 5 6 1 0234567 output current : i o [a] output voltage : v o [v] t a=25 j ta = 125 j ta =-40 j fig.20 current capacitance(v in =12v,vo=5v,f=100khz) (bd9781hfp) 0 1 2 3 4 5 6 1 02 3 4 5 output current : i o [a] output voltage : v o [v] ta = 2 5 j ta = 1 2 5 j ta =-40 j fig.22 current capacitance(v in =12v,vo=5v,f=100khz) (bd9001f) fig.16 on resistance v in =13.2v (bd9001f) fig.19 i o vs efficiency(v in =12v,f=100khz) y (bd9001f) 00.40.81 .2 1.6 2 output current : i o [a] conversion efficiency [%] 5v output 3.3v output 2.5v output 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 fig.14 on resistance v in =13.2v (BD9778F/hfp) fig.15 on resistance v in =7v (bd9001f) 0.5 0.0 1.0 1.5 2.0 2.5 output current : i o [a] fet on resistance : r on [?] ta = 2 5 j ta = 125 j ta =-40 j 00.5 1 1 .5 2 2.5 output current : i o [a] fet on resistance : ron[?] ta = 2 5 j ta = 125 j t a=C40 j 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 fig.13 on resistance v in =7v (BD9778F/hfp) output current : i o [a] 0.5 0.0 1.0 1.5 2.0 2.5 fet on resistance : r on [?] t a=25 j ta = 125 j ta =-40 j 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 00.51 1.522.5 output current : i o [a] fet on resistance : ron[?] ta = 2 5 j 10 20 30 40 50 60 70 80 90 100 0 ta =125 j ta =C40 j 2.5v output 1.5v output 10 20 30 40 50 60 70 80 90 100 0 conversion efficiency [%] output current : i o [a] fig.17 i o vs efficiency(v in =12v,f=200khz) y (bd9781hfp) 0.5 0.0 1.0 1.5 2.0 2.5 3.0 3.3v output 2.5v output 5v output www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
6/16 te chnical note block diagram / application circuit / pin assignment (bd9001f) fig.26 fig.25 no. 12 3 4 5 6 7 fin pin name v in sw rt gnd fb inv en/sync - fig.23 no. 12 3 4 5 6 7 8 function power supply inputoutput error amp output output voltage feedback enable frequency setting resistor connection groundpower system power supply input pin name v in sw fb inv en rt gnd pv in fig.24 no. 12 3 4 5 6 7 fin pin name v in sw fb gnd inv rt en - (BD9778F) (bd9781hfp) (bd9778hfp) 3 vref 220f 1f 33h 330f 390k? 0.1f 4700pf 10k? 23k? 1 8 - ++ - + 4 soft star t osc driver latch tsd - + 6 2 on/off 5 7 en l:offh:on v in pv in inv error amp reset sw v o gnd current limit vref fb rt pwm comparator v in inv sw fb v in gnd rt en pvin en rt inv gnd fb sw v in en/sinc inv fb gnd rt sw v in 150k? 3 vre f 1 - ++ - + 5 soft star t osc driver latch tsd - + 6 2 on/off 7 4 en l:offh:on v in inv error amp reset sw v o gnd current limit vref fb rt pwm comparator v in 220f 1f 33h 330f 390k? 0.1f 4700pf 10k? 23k? 150k? 5 vre f 1 - ++ - + 6 soft star t osc driver latch tsd - + 3 2 sync on/off 7 4 en/sync l:offh:on v in inv error amp reset sw v in v o gnd current limit vref fb rt pwm comparator 220f 1f 33h 330f 390k? 0.1f 4700pf 10k? 23k? 150k? function power supply inputoutput error amp output ground output voltage feedback frequency setting resistor connection enableground function power supply input output frequency setting resistor connection ground error amp output output voltage feedback enable/synchronizing pulse input ground 3 vref soft start 8 - ++ - + 4 osc driver latch tsd - + 6 1 7 inv error amp reset sw v o v in gnd current limit vref v in fb rt pwm comparator inv n.c. fb sw gnd rt en v in 220f 1f 33 h 330f 390k ? 0.1f 4700pf 10k ? 23k ? 150k ? no. 12 3 4 5 6 7 8 yyyyyy function outputnon connection error amp output output voltage feedback enable frequency setting resistor connection ground power supply input pin name sw n.c. fb inv en rt gnd v in www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
7/16 te chnical note description of operations error amp the error amp block is an error amplifier used to input the reference voltage (1 v typ.) and the inv pin voltage. the output fb pin controls the switching duty and output voltage vo. these inv and fb pins are externally mounted to facilitate phase compensation. inserting a capacitor and resistor between these pins enables adjustment of phase margin. (refer to recommended examples on page 11.) sof t start the soft start block provides a function to prevent the overshoot of the output voltage vo through gradually increasing the normal rotation input of the error amplifier when power supply turns on to gradually increase the switching duty. the soft start time is set to 5 msec (t yp.). on/off(BD9778F/hf p,bd9781hfp) setting the en pin to 0.8 v or less makes it possible to shut down the circuit. standby current is set to 0 a (typ.). furthermore, on the bd9781hfp, applying a pulse having a frequency higher than set oscillation frequency to the en/sync pin allows for external synchronization (up to +50% of the set frequency). pwm com parator the pwm comparator block is a comparator to make comparison between the fb pin and internal triangular wave and output a switching pulse. the switching pulse duty varies with the fb value and can be set in the range of 0 to 100%. osc(oscillator) the osc block is a circuit to generate a triangular wave that is to be input in the pwm comparator. connecting a resistor to the rt pin enables setting of oscillation frequency. tsd(thermal shut down) in order to prevent thermal destruction/thermal runaway of this ic, the tsd block will turn off the output when the chip temperature reaches approximately 150?c or more. when the chip temperature falls to a specified level, the output will be reset. however, since the tsd is designed to protect the ic, the chip junction temperature should be provided with the thermal shutdown detection temperature of less than approximately 150?c. curren t limit while the output power p-ch mos fet is on, if the voltage between drain and source (on resistance load current) exceeds the reference voltage internally set with the ic, this block will turn off the output to latch. the overcurrent protection detection values have been set as shown below: bd9781hfp . . . 8a(typ.) bd9001f,BD9778F/hfp . . . 4a(typ.) furthermore, since this overcurrent protection is an automatically reset, after the output is turned off and latched, the latch will be reset with the reset signal output by each oscillation frequency. however, this protection circuit is only effective in preventing destruction from sudden accident. it does not support for the continuous operation of the protection circuit (e.g. if a load, which significantly exceeds the output current capacitance, is normally connected). furthermore, since the overcurrent protection detection value has negative temperature characteristics, consider thermal design. www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
8/16 te chnical note t iming chart (bd9781hfp) - while in basic operation mode - while in overcurrent protection mode fb v in swen/sync internalosc fig.27fig.28 external synchronizing function (bd9781hfp) in order to activate the external synchronizing function, connect the frequency setting resistor to the rt pin and then input a synchronizing signal to the en/sync pin. as the synchronizing signal, input a pulse wave higher than a frequency determined with the setting resistor (rt). on the bd9781hfp, design the frequency difference to be within 50%. furthermore, set the pulse wave duty between 10% and 90%. fig.29 f sync internal osc : for rt only : for external synchronization output short circuit fb sw i o internalosc auto reset auto reset auto reset auto reset www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
9/16 te chnical note description of external components design procedure calculation example vo = output voltage, vin (max.) = maximum input voltage io (max.) = maximum load current, f = oscillation frequency 1. setting or output voltage output voltage can be obtained by the formula shown below. v o =1 x (1+r1/r2) use the formula to select the r1 and r2. furthermore, set the r2 to 30 k? or less. select the current passing through the r1 and r2 to be small enough for the output current. 2. selection of coil (l) the value of the coil can be obtained by the formula shownbelow: l=(v in - v o ) x v o / (v in x f x i o ) i o: output ripple current f = operating frequencyio should typically be approximately 20 to 30% of io. 3. selection of output capacitor (co) the output capacitor can be determined according to the output ripple voltage vo (p-p) required. obtain the required esr value by the formula shown below and then select the capacitance. when v in = 13.2 v, vo = 5 v, io = 2 a, and f = 100 khz, l=(13.2 - 5) x 5/13.2 x 1/100k x 1/(2 x 0.3) =51.8h 47v in =13.2v, vo=5v, l=100h, f=100khz il=(13.2-5) x 5/(100 x 10 -6 x 100 x 10 3 x 13.2) 0.31 when vo = 5 v and r2 = 10 k? , 5=1 x (1+r1/10k?) r1=40k? l=47 h fig.30 v in rt ss sw inv fb gnd c t c in di c o + v o v in c c r c c l r1r2 r t c ss 3.5m x (i limit -io(max)) v o c max = c max =3.5m x (2-1)/5 =700 il=0.31 a c max= 700f if this coil is not set to the optimum value, normal (continuous) oscillation may not be achieved. furthermore, set the value of the coil with an adequate margin so that the peak current passing through the coil will not exceed the rated current of the coil. i l imit:2a(BD9778F/hfp,bd9001f), 4a(bd9781hfp) if this capacitance is not optimum, faulty startup may result.( b 3.5m is soft start time(min.)) when i limit : 2 a, io (max) = 1 a, and vo = 5v, il=(v in -v o ) x v o /(l x f x v in ) vpp=il x esr+(il x vo)/(2 x co x f x v in ) set the rating of the capacitor with an adequate margin to the output voltage. also, set the maximum allowable ripple current with an adequate margin to il. furthermore, the output rise time should be shorter than the soft start time. select the output capacitor having a value smaller than that obtained by the formula shown below . www.rohm.com ? 2010 r ohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
10/16 te chnical note design procedure calculation example 4. selection of diode when v in = 36 v and io = (max.) 2 a, when v in = 13.2 v, vo = 5 v, and io = 1 a, i rms =1 x 5 x (13.2-5)/(13.2) 2 =0.485 5. selection of input capacitor 6. setting of oscillation frequency 7. setting of phase compensation (rc and cc) directions for pattern layout of pcb * the set values listed above are all reference values. on the actual mounting of the ic, the characteristics may vary with the routing of wirings and the types of parts in use. in this connection, it is recommended to thoroughly verify these values on the actual system pri or to use. i rms =0.485 a set diode rating with an adequate margin to the maximum load current. also, make setting of the rated inverse voltage with an adequate margin to the maximum input voltage. a diode with a low forward voltage and short reverse recovery time will provide high efficiency. select a diode of rated current of 2 a or more and rated withstand voltage of 36 v or more. tw o capacitors, ceramic capacitor c in and bypass capacitor c, should be inserted between the v in and gnd.be sure to insert a ceramic capacitor of 1 to 10 f for the c. the capacitor c should have a low esr and a significantly large ripple current. the ripple current i rms can be obtained by the following formula:select capacitors that can accept this ripple current. if the capacitance of cin and c is not optimum, the ic may malfunction. i rms =i o x vo x (vin-v o )/ v in 2 referring fig. 34 and fig. 35 on the following page, select r for the oscillation frequency to be used. furthermore, in order to eliminate noises, be sure to connect ceramic capacitors of 0.1 to 1.0 f in parallel. the phase margin can be set through inserting a capacitor or a capacitor and resistor between the inv pin and the fb pin. each set value varies with the output coil, capacitance, i/o voltage, and load. therefore, set the phase compensation to the optimum value according to these conditions. (for details, refer to application circuit on page 11.) if this setting is not optimum, output oscillation may result. fig.31 1 2 4 3 8 8 6 5 v in sw c co r3c3 r t c t cin r1 r2 signal gnd cx2 cx1 l gnd nmucp fbgnd gnd invrt en bd9778hf p l o a d www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
11 /16 te chnical note phase compensation setting procedure r feedback c fb - + a (1) typical integrator (low pass filter) (2) open loop characteristics of integrator 0 a 0 -90 - 90? - 180? -180 phase [?] gain [db] ff gbw(b) - 20db/decade phase margin (a) the following section describes the stability conditions of the negative feedback system. since the dc/dc converter application is sampled according to the switching frequency, gbw (frequency at 0-db gain) of the overall system should be set to 1/10 or less of the switching frequency. the following section summarizes the targeted characteristics of this application. at a 1 (0-db) gain, the phase delay is 150? or less (i.e., the phase margin is 30? or more). the gbw for this occasion is 1/10 or less of the switching frequency. responsiveness is determined with restrictions on the gbw. to improve responsiveness, higher switching frequency should be provided. replace a secondary phase delay (-180?) with a secondary phase lead by inserting two phase leads, to ensure the stability through the phase compensation. furthermore, the gbw (i.e., frequency at 0-db gain) is determined according to phase compensation capacitance provided for the error amplifier. consequently, in order to reduce the gbw, increase the capacitance value. 1. application stability conditions since the error amplifier is provided with (1) or (2) phase compensation, the low pass filter is applied. in the case of the dc/dc converter application, the r becomes a parallel resistance of the feedback resistance. bmqagjj_rgmldpcosclaw%qep_nft_jscgq rwnga_jt_jsc* mqagjj_rgmldpcosclawgqlcacqq_pwrmamlqgbcp : 0.#_qbgqncpqgml, fig.35 r t vs f osc & bd9001f ' 50 100 150 200 250 300 100 50 200 300 400 500 600 700 800 oscilating frequency setting resistance : rt [k?] oscilating frequency : fosc[khz] fig.34 r t vs f osc (bd9781hfp/BD9778F/hfp) 800 50 100 150 200 250 300 350 400 450 500 100 02 0 0 300 400 500 600 700 oscilating frequency setting resistance : r t [k?] oscilating frequency : fosc[khz] fig.32 bd9001f reference layout pattern fig.33 bd9781hfp reference layout pattern b as shown above, design the gnd pattern as large area as possible within inner layer. b gray zones indicate gnd. co l c cin di r t r3 cx1 r1 c3 cx2 r2 c t co l c cin di cx1 r3 c3 cx2 r2 r1 r t c t www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
12/16 te chnical note l c + v cc v o l r esr c v cc v o (1) lc resonant circuit (2) with esr provided fr = 1 [hz] at this resonance point, a -180? a -90? ph ase-delay occurs. phase-delay occurs. (3) insert feedback resistance in the c. (4) insert the r3 in integrator . c1 v o r1r2 c2 fb inv - + a v o r1r2 r3 c2 fb inv - + a 3. for output capacitors having low esr, such as low impedance electrolyte capacitor or os-con (1) phase compensation with secondary phase lead v o r1 c1 r2 r3 c2 fb inv - + a for output capacitors that have high esr (i.e., several ?), the phase compensation setting procedure becomes comparatively simple. since the dc/dc converter application has a lc resonant circuit attached to the output, a -180? phase-delay occurs in that area. if esr component is present, howeve r, a +90? phase-lead occurs to shift the phase delay to -90?. since the phase delay should be set within 150?, it is a very effective method but tends to increase the ripple component of the output voltage. to cancel the lc resonance, the frequency to insert the phase lead should be set close to the lc resonant frequency. the settings above have are estimated. consequently, the settings may be adjusted on the actual system. furthermore, since these characteristics vary with the layout of pcb loading conditions, precise calculations should be made on the actual system. in order to use capacitors with low esr (i.e., several tens of m?), two phase-leads should be inserted so that a -180? phase-delay, due to lc resonance, will be compensated. the following section shows a typical phase compensation procedure. to set phase lead frequency, insert both of the phase leads close to the lc resonant frequency. according to empirical rule, setting the phase lead frequency f z2 with r3 and c2 lower than the lc resonant frequency fr, and the phase lead frequency f z1 with the r1 and c1 higher than the lc resonant frequency fr, will provide stable application conditions. according to changes in phase characteristics, due to the esr, only one phase lead should be inserted. for this phase lead, select either of the methods shows below: 2. for output capacitors having high esr, such as electrolyte capacitor ( ) www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
13/16 te chnical note 1. check to ensure output causes no oscillation at the maximum load in closed loop. isolate (1) and (2) and insert vm (with amplitude of approximately 100 mvpp). measure (probe) the oscillation of (1) to that of (2). 2. 3. heat loss furthermore, the phase margin can also be measured with the load responsiveness. measure variations in the output voltage when instantaneously changing the load from no load to the maximum load. even though ringing phenomenon is caused, due to low phase margin, no ringing takes place. phase margin is provided. however, no specific phase margin can be probed. to measure the open loop of dc/dc converter, use the gain phase analyzer or fra to measure the frequency characteristics. ra measurement of open loop of dc/dc converter the heat loss w of the ic can be obtained by the formula shown below:w=ron x io 2 x + v in x i cc + tr x v in x io x f ron: on resistance of ic (refer to pages 4 and 5.) io: load current vo: output voltage v in : input voltage icc: circuit current (refer to pages 2 and 3) tr: switching rise/fall time (approximately 40 nsec) f : oscillation frequency vo v in 1r on x io 2 22 x =tr x v in x io x f x tr x x v in x io 2 1 t 1 1 tr v in gnd swwaveform t = f 1 2 v o v m + r l ~ dc/dc converter controller load output voltage maximum load t adequate phase margin inadequate phase margin 0 oc oc www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
14/16 te chnical note fig.36 equivalent circuit fig.37 t ypical simple construction of monolithic ic p la yer e b c (pin b) tran sistor (npn) p n n n n gnd parasitic element gnd p + p + (pin a) gnd parasitic element (pin b) gnd b e c parasitic element p + p la yer (pin a) resistor p n n n gnd parasitic element p + notes for use 1) absolute maximum ratings an excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. if any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices, such as fuses. furthermore, don't turn on the ic with a fast rising edge of v in . ( rise time << 10v / sec ) 2) gnd potential gnd potential should maintain at the minimum ground voltage level. furthermore, no terminals should be lower than the gnd potential voltage including an electric transients. 3) thermal design use a thermal design that allows for a sufficient margin in light of the power dissipation (pd) in actual operating conditions. 4) inter-pin shorts and mounting errors use caution when positioning the ic for mounting on printed circuit boards. the ic may be damaged if there is any connection error or if positive and ground power supply terminals are reversed. the ic may also be damaged if pins are shorted together or are shorted to other circuits power lines. 5) operation in strong electromagnetic field use caution when using the ic in the presence of a strong electromagnetic field as doing so may cause the ic to malfunctio n. 6) inspection with set printed circuit board when testing the ic on an application board, connecting a capacitor to a pin with low impedance subjects the ic to stress. always discharge capacitors after each process or step. always turn the ic's power supply off before connecting it to, or removing it from a jig or fixture, during the inspection process. ground the ic during assembly steps as an antistatic measure. use similar precaution when transporting and storing the ic. vin en/sync 222 k 221 k 2k vrega 139 k 145 k sw sw en vin 10k 300k 250k vin 2k 300k 50k rt vin vref vin en/sync & bd9781hfp ' en & BD9778F/hfp, bd9001f ' 1k vin fb vref 1k inv vin vref fb & BD9778F/hfp, bd9781hfp ' inv rt fb & bd9001f ' 1k vin fb vref 1k www.rohm.com ? 2010 rohm co., ltd. all rights reserved. BD9778F, bd9778hfp, bd9001f, bd9781hfp dec.2015 - rev.c downloaded from: http:///
15/16 te chnical note thermal derating characteristics fig.39 fig.40 10) on the application shown below, if there is a mode in which v in and each pin potential are inverted, for example, if the v in is short-circuited to the ground with external diode charged, internal circuits may be damaged. to avoid damage, it is recommended to insert a backflow prevention diode in the series with v in or a bypass diode between each pin and v in . fig.35 pin backflow prevention diode bypass diode vcc 8) ground wiring pattern it is recommended to separate the large-current gnd pattern from the small-signal gnd pattern and establish a single ground at the reference point of the set pcb, so that resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal gnd. prevent fluctuations in the gnd wiring pattern of external parts. 9) te mperature protection (thermal shut down) circuit this ic has a built-in temperature protection circuit to prevent the thermal destruction of the ic. as described above, be sure to use this ic within the power dissipation range. should a condition exceeding the power dissipation range continue, the chip temperature tj will rise to activate the temperature protection circuit, thus turning off the output power element. then, when the tip temperature tj falls, the circuit will be automatically reset. furthermore, if the temperature protection circuit is activated under the condition exceeding the absolute maximum ratings, do not attempt to use the temperature protection circuit for set design. single piece of ic pcb size: 70 x 70 x 1.6 mm 3 (pcb incorporates thermal via.) copper foil area on the front side of pcb: 10.5 x 10.5 mm 2 2-layer pcb (copper foil area on the reverse side of pcb: 15 x 15 mm 2 ) 2-layer pcb (copper foil area on the reverse side of pcb: 70 x 70 mm 2 ) 4-layer pcb (copper foil area on the reverse side of pcb: 70 x 70 mm 2 ) single piece of ic when mounted on rohm standard pcb (glass epoxy pcb of 70 mm x 70 mm x 1.6 mm) 10 9 8 7 6 5 4 3 2 1 0 7.3w ?k@gclrrckncp ?rsp c r_ *j+ 5.5w 2.3w 1.4w 25 50 75 hrp7 100 125 150 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 25 05 0 7 5 sop8 100 125 150 nmucpbgqqgn?rgml pd [ w ] nmucpbgqqgn?rgml pd [ w ] ?k@gclrrckncp ?rsp c r_ *j + BD9778F bd9001f BD9778F, bd9778hfp, bd9001f, bd9781hfp www.rohm.com ? 2010 rohm co., ltd. all rights reserved. 7) ic pin input (fig. 37) this monolithic ic contains p+ isolation and p substrate layers between adjacent elements to keep them isolated. p-n junctions are formed at the intersection of these p layers with the n layers of other elements, creating a parasitic diode or transistor. for example, the relation between each potential is as follows: when gnd > pin a and gnd > pin b, the p-n junction operates as a parasitic diode. when pin b > gnd > pin a, the p-n junction operates as a parasitic transistor. parasitic diodes can occur inevitably in the structure of the ic. the operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. accordingly , methods by which parasitic diodes operate, such as applying a voltage that is lower than the gnd (p substrate) voltage toan input pin, should not be used. dec.2015 - rev.c downloaded from: http:///
16/16 te chnical note selection of order type packagef = sop8 hfp = hrp7 ta p i n g t y p e e2 = reel-type embossed carrier tape (sop8) tr = reel-type embossed carrier tape (hrp7) sop8 hrp7 BD9778F, bd9778hfp, bd9001f, bd9781hfp www.rohm.com ? 2010 rohm co., ltd. all rights reserv ed. b d 9 7 7 8h f p - t r part no. 9778 = 36v/2a9781 = 36v/4a 9001 = 50v/2a part no. ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tapequantity direction of feed the direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand 2500pcs e2 () direction of feed reel 1pin direction of feed 1pin reel ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tapequantity direction of feed the direction is the 1pin of product is at the upper right when you hold reel on the left hand and you pull out the tape on the right hand 2000pcs tr ( ) dec.2015 - rev.c downloaded from: http:///
datasheet d a t a s h e e t notice-pab-e rev.00 2 ? 2015 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. if you intend to use our products in devices requiring extremely high reliability (such as medical equipment (note 1) , aircraft/spacecraft, nuclear power controllers, etc.) and whos e malfunction or failure may cause loss of human life, bodily injury or serious damage to property (specific applications), please consult with the rohm sales representative in advance. unless otherwise agreed in writ ing by rohm in advance, rohm shall not be in any way responsible or liable for any damages, expenses or losses in curred by you or third parties arising from the use of any rohms products for specific applications. (note1) medical equipment classification of the specific applications japan usa eu china class class class b class class ? 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 responsibilities, adequate safety measures including but not limited to fail-safe desi gn 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 products are not designed under any special or extr aordinary environments or conditi ons, 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 products under an y 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 verification and confirmation of product performance, reliability, etc, prior to use, must be necessary: [a] use of our products in any types of liquid, incl uding water, oils, chemicals, and organic 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 ar e 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 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 (ev en 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 subjec t to radiation-proof 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 per iod of time, such as pulse. is applied, confirmation of performance characteristics after on-boar d mounting is strongly recomm ended. avoid applying power exceeding normal rated power; exceeding the power rating under steady-state loading c ondition may negatively affect product performance and reliability. 7. de-rate power dissipation depending on ambient temperature. when used in sealed area, c onfirm that it is the use in the range that does not exceed t he maximum junction temperature. 8. confirm that operation temperat ure is within the specified range described in the product specification. 9. rohm shall not be in any way responsible or liable for fa ilure induced under deviant condi tion from what is defined in this document. precaution for mounting / circuit board design 1. when a highly active halogenous (chlori ne, bromine, etc.) flux is used, the resi due 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. if the flow sol dering method is preferred on a surface-mount products, please consult with the rohm representative in advance. for details, please refer to rohm mounting specification downloaded from: http:///
datasheet d a t a s h e e t notice-pab-e rev.00 2 ? 2015 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, pl ease allow a sufficient margin considering variations of the characteristics of the products and external components, including transient characteri stics, as well as static characteristics. 2. you agree that application notes, re ference designs, and associated data and in formation contained in this document are presented only as guidance for products use. theref ore, in case you use such information, you are solely responsible for it and you must exercise your own indepen dent verification and judgment in the use of such information contained in this 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 product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. please take proper caution in your manufacturing process and storage so that voltage exceeding t he products maximum rating will not be applied to products. please take special care under dry condit ion (e.g. grounding of human body / equipment / solder iron, isolation from charged objects, se tting of ionizer, friction prevention and temperature / humidity control). precaution for storage / transportation 1. product performance and soldered connections may deteriora te if the products are stor ed in the places where: [a] the products are exposed to sea winds or corros ive gases, including cl2, h2s, nh3, so2, and no2 [b] the temperature or humidity exceeds those recommended by rohm [c] the products are exposed to di rect sunshine or condensation [d] the products are exposed to high electrostatic 2. even under rohm recommended storage c ondition, solderability of products out of recommended storage time period may be degraded. it is strongly recommended to confirm sol derability before using products of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the co rrect direction, which is indicated on a carton with a symbol. otherwise bent leads may occur due to excessive stress applied when dropping of a carton. 4. use products within the specified time after opening a humidity barrier bag. baking is required before using products of which storage time is exceeding the recommended storage time period. precaution for product label qr code printed on rohm products label is for rohms internal use only. precaution for disposition when disposing products please dispose them proper ly using an authorized industry waste company. precaution for foreign exchange and foreign trade act since concerned goods are fallen under lis ted items of export control prescribed by foreign exchange and foreign trade act, the permission based on the act is necessary in case of export. precaution regarding intellectual property rights 1. all information and data including but not limited to application example contained in this document is for reference only. rohm does not warrant that foregoi ng information or data will not infringe any intellectual property rights or any other rights of any third party regarding such information or data. 2. rohm shall not have any obligations where the claims, actions or demands arising from the co mbination 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 informati on contained in this document. pr ovided, however, that rohm will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to manufacture or sell products containing the produc ts, subject to the terms and conditions herein. other precaution 1. this document may not be reprinted or reproduced, in whol e 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 wa y whatsoever the products and the related technical information contained in the products or this document for any military purposes, incl uding 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. downloaded from: http:///
datasheet datasheet notice C we rev.001 ? 201 5 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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