72 features ? compact full-mold package (equivalent to to220) ? output current: 3.0a ? high efficiency: 79 to 91% ? requires only 4 external components ? phase correction and output voltage adjustment performed internally ? built-in reference oscillator (60khz) ? built-in overcurrent and thermal protection circuits ? built-in soft start circuit (output on/off control) applications ? power supplies for telecommunication equipment ? onboard local power supplies lineup full-mold, separate excitation switching type si-8000s series unit v a c symbol v in i o t jop symbol v in p d1 p d2 t j t stg v sw r th(j-c) *si-8033s: 35v recommended operating conditions absolute maximum ratings unit v w w c c v c/w parameter dc input voltage range output current range operating junction temperature range parameter dc input voltage power dissipation junction temperature storage temperature sw terminal applied reverse voltage thermal resistance(junction to case) ratings 43 * 18(with infinite heatsink) 1.5(without heatsink, stand-alone operation) +125 C 40 to +125 C 1 5.5 part number si-8033s si-8050s si-8090s si-8120s si-8150s v o (v) 3.3 5.0 9.0 12.0 15.0 i o (a) 3.0 ratings si-8033s si-8050s si-8090s si-8120s si-8150s 5.5 to 28 7 to 40 12 to 40 15 to 40 18 to 40 0 to 3.0 C 30 to +125 si-8000s series
73 symbol v o conditions conditions f conditions ? v oline conditions ? v oload conditions ? v o / ? t a r rej conditions i s1 conditions ratings si-8033s si-8050s si-8090s si-8120s si-8150s min. typ. max. min. typ. max. min. typ. max. min. typ. max. min. typ. max. 3.17 3.30 3.43 4.80 5.00 5.20 8.55 9.00 9.45 11.50 12.00 12.50 14.25 15.00 15.75 3.234 3.30 3.366 4.90 5.00 5.10 8.73 9.00 9.27 v in =15v, i o =1.0a v in =20v, i o =1.0a v in =21v, i o =1.0a v in =24v, i o =1.0a v in =25v, i o =1.0a 79 84 88 90 91 v in =15v, i o =1.0a v in =20v, i o =1.0a v in =21v, i o =1.0a v in =24v, i o =1.0a v in =25v, i o =1.0a 60 60 60 60 60 v in =15v, i o =1.0a v in =20v, i o =1.0a v in =21v, i o =1.0a v in =24v, i o =1.0a v in =25v, i o =1.0a 25 80 40 100 50 120 60 130 60 130 v in =8 to 28v, i o =1.0a v in =10 to 30v, i o =1.0a v in =15 to 30v, i o =1.0a v in =18 to 30v, i o =1.0a v in =21 to 30v, i o =1.0a 10 30 10 40 10 40 10 40 10 40 v in =15v, i o =0.5 to 1.5a v in =20v, i o =0.5 to 1.5a v in =21v, i o =0.5 to 1.5a v in =24v, i o =0.5 to 1.5a v in =25v, i o =0.5 to 1.5a 0.5 0.5 1.0 1.0 1.0 45 45 45 45 45 f=100 to 120h z f=100 to 120h z f=100 to 120h z f=100 to 120h z f=100 to 120h z 3.1 3.1 3.1 3.1 3.1 v in =15v v in =20v v in =21v v in =24v v in =25v si-8000s series a. part number b. lot number c. logo mark pin arrangement q v in w sw out e gnd r v os t s.s plastic mold package type flammability: ul94v-0 weight: approx. 2.3g forming no. 1101 external dimensions electrical characteristics (t a =25 c) (unit: mm) 10.0 0.2 4.2 0.2 0.95 0.15 8.2 0.7 2.6 0.1 3.9 0.7 (4.3) (4.6) (8.0) (17.9) (2.0) 0.85 +0.2 C 0.1 0.45 +0.2 C 0.1 3.2 0.2 4.0 0.2 7.9 0.2 5.0 0.6 16.9 0.3 0.5 12345 p1.7 0.7 4=6.8 0.7 2.8 0.2 a b c parameter si-8000s* 1 output si-8000ss voltage efficiency switching frequency line regulation load regulation temperature coefficient of output voltage ripple rejection overcurrent protection starting current unit v % kh z mv mv mv/ c db a *1: s may be indicated to the right of the sanken logo (except si-8120s, si-8150s)
74 block diagram standard external circuit t a -p d characteristics 2 reg. ocp osc reset amp. tsd v ref comp. drive 1 4 v os v in sw out gnd s.s. 53 v in c 1 d 1 l 1 v in v o gnd s.s gnd gnd si-8000s sw out v os 1 2 3 + c 2 + 5 4 15 20 10 5 0 C 25 0 25 50 ambient operating temperature t a ( c) power dissipation p d (w) 75 125 100 200 200 2mm (2.3 c/w) 100 100 2mm (5.2 c/w) 75 75 2mm (7.6 c/w) infinite heatsink without heatsink with silicon grease heatsink: aluminum c 1,2 : 1000 f l 1 : 150 h d 1 : rk46(sanken) the efficiency depends on the input voltage and the out- put current. thus, obtain the value from the efficiency graph on page 75 and substitute the percentage in the formula above. v o : output voltage v in : input voltage i o : output current x : efficiency (%) v f : diode forward voltage 0.5v(rk46) thermal design for d 1 must be considered separately. p d =v o ? i o 100 C 1 C v f ? i o 1 C v o ? v in si-8000s series
75 typical characteristics output voltage(si-8050s) efficiency characteristics(si-8050s) load regulation(si-8050s) temperature characteristics(si-8050s) overcurrent protection characteristics(si-8050s) thermal protection characteristics(si- 8050s) output voltage(si-8120s) efficiency characteristics(si-8120s) load regulation(si-8120s) 0 10 8 6 4 2 0 24 6 input voltage v in (v) output voltage v o (v) 81012 * load=c.c ta=25 c 3a 1a i o =0a output current i o (a) efficiency (%) 0 100 90 80 70 60 50 0 0.5 1.0 1.5 2.0 2.5 3.0 t a =25 c v in =40v 7v 10v 20v output voltage v o (v) output current i o (a) 0 5.15 5.10 5.05 5.00 4.95 0 0.5 1.0 1.5 2.0 2.5 3.0 t a =25 c 10v v in =40v 7v 20v output voltage v o (v) C 50 100 90 80 70 60 0 5.15 5.10 5.05 5.00 4.95 0 C 25 0 25 ambient temperature t a ( c) efficiency (%) frequency f (khz) 50 75 100 (v in =20v,i o =1a) v o f output voltage v o (v) output current i o (a) 0 10 8 6 4 2 0 123456 t a =25 c 20v 40v v in =7v output voltage v o (v) 50 10 8 6 4 2 0 75 100 125 ambient temperature t a ( c) 150 175 200 (v in =20v,i o =0a) tsd on tsd off t a =25 c 24v 15v output current i o (a) efficiency (%) 0 100 90 80 70 60 50 0 0.5 1.0 1.5 2.0 2.5 3.0 v in =40v output current i o (a) t a =25 c output voltage v o (v) 0 12.3 12.2 12.1 12.0 11.9 0 0.5 1.0 1.5 2.0 2.5 3.0 24v 15v v in =40v note on thermal protection: the thermal protection circuit is intended for protection against heat during instantaneous short-circuiting. its operation is not guaran- teed for continuous heating condition such as short-circuiting over extended periods of time. si-8000s series 0 25 20 15 10 5 0 51015 input voltage v in (v) output voltage v o (v) 20 25 30 * load=c.c t a =25 c i o =0a 1a 3a
76 application notes 1. selecting external components (1) choke coil l 1 to maintain the stable operation of the regulator, choke coil l 1 should be selected appropriately. when selecting choke coil l 1 , consider the following: a) suitable for a switching regulator do not use a coil as a noise filter because it generates excess heat. b) appropriate inductance the greater the inductance of the choke coil, the smaller the output ripple voltage. however, the size of the coil increases large as the inductance increases. if the inductance is low, a greater peak current flows to the ic and loss increases. this is not favorable for stable operation. the standard external circuit shows reference inductance val- ues suitable for stable operation. however, the appropriate inductance may also be calculated as follows: l= (v in C v o ) ? v o ? il ? v in ? f where, ? il indicates the ripple current of the choke coil that is roughly set as follows: ? if the output current is close to the maximum rating (3 a) of si-8000s ripple current = output current 0.2 to 0.3 ? if the output current is about 1.0a or less ripple current = output current 0.3 to 0.4 c) satisfying the rated current the rated current of a choke coil must be greater than the maximum load current. note that the inductance decreases drastically and an excess current flows if the load current ex- ceeds the rated current of the coil. d) good dc current superposition characteristics the current flowing through a choke coil is a triangular wave- form current superimposed on a dc current equal to the load current. the coil inductance decreases as the load current increases. in general, the coil can be used until the induc- tance drops to 50% of the rated value. use this as the refer- ence value for selection. 100% 50% i o (max.) inductance load current e) less noise a drum-type open magnetic core coil can affect peripheral circuits with noise because the flux passes outside the coil. to avoid this problem, use a toroidal, ei, or ee type closed magnetic core coil. si-8000s series (2) input capacitor c 1 input capacitor c 1 operates as a bypass capacitor in the input circuit. when selecting input capacitor c 1 , consider the following: a) the breakdown voltage is higher than the maximum input volt- age. b) satisfies the allowable ripple current exceeding the ratings of this capacitor or using it without de- rating may reduce its service life and also cause the regulator to malfunction. therefore, an input capacitor with a sufficient margin should be selected. with the si-8000s series, the effective ripple current irms flowing to the input capacitor can be calculated approximately as follows: i rms 1.2 v o i o v in (3) output capacitor c 2 output capacitor c 2 operates as a smoothing capacitor for switch- ing output. the output ripple voltage from the regulator is deter- mined by the product of the pulsating current part ? il (=c 2 charge- discharge current) of the choke coil current and the equivalent series resistance esr of the output capacitor c 2 . v rip = ? il ? c2esr therefore, a capacitor of low equivalent series resistance esr should be selected to reduce the output ripple voltage. it is rec- ommended to select a low-impedance capacitor intended for use with switching regulators as c 2 . (4) diode d 1 use a schottky barrier diode for d 1 . if you use a general rectifier diode or fast recovery diode, the ic may be damaged. (sanken rk46 recommended) 2. cautions on pattern design (1) large current line since a large current flows through the bold lines in the standard external circuit make the pattern as wide and as short as pos- sible. 2 1 3 4 si-8000s v in gnd c 1 c 2 l 1 d 1 v out gnd + + (2) input capacitor place the input capacitor c 1 and output capacitor c 2 as close to the ic as possible. since a large current flows through the lead wires of the input and output capacitors to charge and discharge them quickly, minimize the lead wire length. the pattern around the capacitors should also be minimized. c 1 . c 2 . c 1 . c 2 . + + example of bad pattern example of good pattern
77 1. soft start connecting a capacitor to terminal no. 5 permits a soft start at power- on. delay time t d and rise time t s can roughly be calculated as shown below. (however, the values may slightly vary in an actual application.) if the capacitance of c 3 is increased, it takes longer to discharge c 3 after v in is turned off. therefore, it is recommended to set the value to 10 f or less. when not using the soft start function, keep terminal no. 5 open. t d = 0.7 c 3 (sec) 20 10 C 6 t s = 4.845 c 3 (sec) v in 20 10 C 6 si-8000s s. s. c 3 v in v o t d t s 5 2. output on/off control output can be turned on and off by using the soft start terminals. set the soft start terminal voltage to v ssl (0.2v typ.) or less to stop output. to switch the potential at the soft start terminals, drive the open collector of the transistor. since the discharge current from c 3 flows to the on/off control transistor, limit the current for protec- tion. the ss terminal is pulled up to the power supply in the ic and no external voltage can be applied. si-8000s s. s + on/off s. s. 5 c 3 si-8000s s. s. 5 on/off applications si-8000s series (3) sensing terminal output voltage sensing terminal v os should be connected as close to output capacitor c 2 as possible. if the terminal is far from the capacitor, the decreasing regulation and increasing switching ripple may result in abnormal oscillation. + l15 v out v in gnd c 1 c 2 d 1 si-8000s example of basic pattern top view (with part names) 3. variable output voltage the output voltage can be increased by connecting a resistor to v os terminal no. 4. (there is no way of decreasing the voltage) (1) variable output voltage with single external resistor si-8000s 2 4 v o ' gnd c 2 r ex v s iv s l 3 the output voltage adjustment resistance r ex is calculated as follows: r ex = v o ' C v s iv s v s : output voltage of product v o ' : adjusted output voltage i vs : inflow current to vs terminal * the temperature characteristics of output voltage worsen because the value r ex is not compensated for temperature. the vs value fluctuates by up to 20% depending on the ic product. since the output voltage fluctuates more, a semi-fixed resistor is necessary for accurate output voltage adjustment. if vs and r ex are constant, the range of output voltage fluctuation can be expressed as follows: ? v o '(%)= 20 ? v o ' C v s v o ' ? v o ': adjusted output voltage (2) variable output voltage with two external resistors si-8000s 2 4 v o gnd c 2 r ex1 r ex2 ir ex1 iv s v s l 3 the output voltage adjustment resistances r ex1 and r ex2 are calculated as follows: r ex 1= v o ' C v s s ? iv s r ex 2= v s (s-1) ? iv s s:stability factor bypassing the current to r ex2 improves the temperature charac- teristics and voltage fluctuation ranges more than the method of (1). stability factor s indicates the ratio of r ex1 to vs terminal inflow current. increasing the s value improves the fluctuations of the temperature characteristics and output voltage. (usually 5 to 10) if the vs and r ex values are constant, the output voltage fluctua- tion range can be calculated as follows: ? v o '(%)= 20 ? v o ' C v s s v o '
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