22 ics 1-1-3 dc/dc converter ics features surface-mount 16 pin package output current: 3.0a high efficiency: 91% (at v in = 10v, l o = 1a, v o = 5v) capable of downsizing a choke-coil due to ic's high switching frequency (125khz). (com- pared with conventional sanken devices) the output-voltage-variable type can vary its output voltage from 1v to 14v because of its low reference voltage (vref) of 1v. ? ide input voltage range (8 to 50v) output on/off available built-in overcurrent and thermal protection circuits absolute maximum ratings unit v w c c c/w c/w ratings 53 2.4 +125 ?0 to +125 18 50 symbol v in p d *1, *2 t j t stg j-c *2 j-a *2 parameter dc input voltage power dissipation junction temperature storage temperature thermal resistance (junction to case) thermal resistance (junction to ambient air) (t a =25 c) parameter dc input voltage range output voltage range output current range *2 operating junction temperature range operating temperature range symbol v in v o i o t jop t op ratings spi-8010a (8 or v o +3) *1 to 50 1 to 14 0.02 to 3.0 *2 ?0 to +125 ?0 to +125 *1: the minimum value of an input voltage range is the higher of either 8v or v o +3v. *2: please be sure to let the output current run more than 20 ma. when using by less than 20 ma, there is a possibility that the output voltage becomes unstable. recommended operating conditions *1: limited due to thermal protection. *2: when mounted on glass-epoxy board 700cm 2 (copper laminate area 30.8cm 2 ). electrical characteristics unit v % kh z mv mv mv/ c a ma a v a parameter reference voltage efficiency oscillation frequency line regulation load regulation t emperature coefficient of reference voltage overcurrent protection starting current quiescent circuit current circuit current at output off ce/ss low level voltage t erminal outflow current at low voltage symbol v ref conditions eff conditions f osc conditions ? v oline conditions ? v oload conditions ? v ref / ? t a i s conditions i q conditions i q ( off ) conditions v ssl i ssl conditions (t a =25 c) * pin 4 is the ce/ss pin. soft start at power on can be performed with a capacitor connected to this pin. the output can also be turned on/off with this pin. the output is stopped by setting the voltage of this pin to v ssl or lower. ce/ss-pin voltage can be changed with an open- collector drive circuit of a transistor. when using both the soft-start and on/off functions together, the discharge current from c 4 flows into the on/off control transistor. therefore, limit the current securely to protect the transistor if c 3 capacitance is large. the ce/ss pin is pulled up to the power supply in the ic, so applying the external voltage is prohibited. rating spi-8010a (variable type) min. typ. max. 0.97 1.00 1.03 v in =12v, i o =1a 86 v in =20v, i o =1a, v o =5v 250 v in =12v, i o =1a 20 40 v in =10 to 30v, i o =1a 10 30 v in =12v, i o =0.1 to 1.5a 0.5 3.1 v in =12v 7 v in =12v, i o =0a 400 v in =12v, v on/off =0.3v 0.5 50 v ssl =0v surface mount, separate excitation step-down switching mode spi-8000a series applications onboard local power supplies ? a equipment for stabilization of the secondary-side output voltage of switching power supplies spi-8000a spi-8000a ce/ss 4 ce/ss 4 ce/ss c4 c4 4 v o. on/off soft start soft start +v o. on/off spi-8000a unit v v a c c
23 ics spi-8000a series external dimensions (hsop16) (unit : mm) block diagram 18 10.5 0.2 16 9 16 9 (11) 12.2 0.2 1.27 0.25 0.4+0.15/-0.05 0.25+0.15/-0.05 (gate remains: not included in dimensions) 18 s s 0.10 2.75max 2.5 0.2 2.0+0.2/-0.08 10.5 0.3 (2) (4.5) 7.5 0.2 1+0.1/-0.05 (heatsink thickness) ce/ss uvlo ocp p.reg osc pwm logic ce/ss tsd reg comp gnd 1v boot reg drive bs sw out v ref v in + - + - amp spi-8010a pin assignment 1.agnd 2.n.c 3.dgnd 4.ce/ss 5.reg 6.n.c 7.sw out 8.n.c 9.n.c 10.n.c 11.v in 12.b.s 13.n.c 14.c omp 15.v ref 16.n.c product mass : approx 0.86g
24 ics 1-1-3 dc/dc converter ics t a -p d characteristics t ypical connection diagram spi-8010a c1: 220 f/63v c2: 470 f/25v c3: 0.1 f c4: 1000pf c5: 0.1 f c6: 0.047 f c7: 0.1 f c8: 0.1 f r1: 47 ? l1: 47 h d1: spb-g56s (sanken) diode d 1 be sure to use a schottky-barrier diode for d 1 . if other diodes like fast recovery diodes are used, ics may be destroyed because of the reverse voltage generated by the recovery voltage or on voltage. choke coil l 1 if the winding resistance of the choke coil is too high, the efficiency may drop below the rated value. as the overcurrent protection starting current is about 4.5a, take care concerning heat radiation from the choke coil caused b y magnetic saturation due to overload or short-circuited load. capacitors c 1 , c 2 as large ripple currents flow through c 1 and c 2 , use high-frequency and low-impedance capacitors aiming for switching-mode-power-supply use. especially when the impedance of c 2 is high, the switching waveform may become abnormal at low temperatures. for c 2 , do not use a capacitor with an extremely low equivalent series resistance (esr) such as an os capacitor or a tantalum capacitor, which may cause an abnormal oscillation. resistors r 2 , r 3 ? 2 and r 3 are the resistors to set the output voltage. set their values so that i ref becomes approx. 2ma. obtain r 2 and r 3 values by the following formula: to create the optimum operating conditions, place the components as close as possible to each other. reg ce/ss 53 4 v in sw out v ref v in gnd v 0 gnd 11 c5 comp 14 12 c6 c3 d1 l1 r2 r3 i ref agnd dgnd b.s spi-8010a 1 15 7 r1 c4 c1 c7 + c2 c8 + note 1: the ef ficiency depends on the input voltage and the output cur- rent. therefore, obtain the value from the efficiency graph and substitute the percentage in the formula above. note 2: thermal design for d 1 must be considered separately. v o : output voltage v in : input voltage i o : output current ? : efficiency (%) v f : diode d 1 forward voltage spb-g56s?.4v(i o =2a) 3.00 2.50 2.00 1.50 1.00 0.50 0 ?0 0 25 50 75 100 125 power dissipation p d (w) ambient temperature t a ( c) j-a:62.5 c/w(0.84cm 2 ) j-a:47.6 c/w(8.64cm 2 ) j-a:41.7 c/w(30.8cm 2 ) p d =v o ?i o 100 ? ? f ?i o 1 v o ? v in r2= (v out ? ref ) = (v out ?) ( ? ), r3 = v ref = 1 500( ? ) i ref 2 10 ? i ref 2 10 ? = . .
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