n2206/32406hkim 5-5607 no.a0295-1/7 STK755-030 overview the STK755-030 is a step-down chopper-type dedicated 12v single output regulator that uses a power mosfet as its switching element. in 3-pin regulators and other dropper systems, this device can accommodate wide range of input voltages that has been difficult to supp ort. using only input and output capac itors and choke coils as its external components, the device enables chopper regulators with a high current (7a) to be configured as though they were 3-pin regulators. the STK755-030 can offer broad-based support for power supply circuits in many different fields as a secondary side regulator in switching power supplies or as an output regulat or after ac transformer rectification to standardize or rationalize power supply circuit design. applications power supply for game and amusement machines power supply for equipment relating to office automation and factory automation secondary side regulator in switching power supplies features input from single power supply supported typical efficiency of 88% at dc 30v input, 12v/5a output built-in reverse going linear overload charact eristic curve overcurr ent protection circuit 125khz (typ.) operating frequency power mosfet used built-in cut-off function to enable on/off control of the output using an external signal ordering number : ena0295 thick-film hybrid ic 12v/7a single output mos chopper regulator
STK755-030 no.a0295-2/7 specifications maximum ratings at ta = 25 c, tc = 25 c unless otherwise specified parameter symbol conditions ratings unit operating ic substrate temperature tc max +105 c operating ambient temperature topr -10 to +85 c storage ambient temperature tstg -30 to +105 c dc input voltage v in max 60 v output current i o max 7a recommended operating conditions parameter symbol conditions ratings unit operating ic substrate temperature tc 0 to +85 c dc input voltage v in 20 to 40 v load current i o 0 to 7 a electrical characteristics at ta=25c, v dd , in the specified circuit, v in =30v unless otherwise specifide ratings parameter symbol conditions min typ (*1) max unit output voltage v o v in =24v, i o =1a 11.8 12.0 12.2 v ripple voltage vrp i o =7a 50 100 mvp-p total regulation reg v in =20 to 40v i o =1 to 7a tc=+25 to +85c 11.7 12.3 v overcurrent protection start current iocp 7 11 a efficiency i o =5a 88 % operating frequency fosc i o =1a 125 khz * 1: the figures in this column represent de sign targets and are not guaranteed values. package dimensions unit : mm 4210 46.6 41.2 12.7 25.5 (6.63) 11 2.54=27.94 3.6 0.5 2.54 8.5 9.0 0.4 2.9 1.0 1 12
STK755-030 no.a0295-3/7 block diagram note: the rear side of this ic is not perfectly insulated. therefore, its voltage potential may be set to ground level (pin (7)). bear this in mind at times when mounting a heat sink or the like. pin descriptions pin no. pin name description 1 onf remote on/off (must be held open when not to be used) 2 vadj output voltage fine adjustment (mus t be held open when not to be used) 3, 4 v o output voltage sensing 5, 6 ocp overcurrent sensing 7 gnd ground 8, 9 fwd flywheel diode anode 10, 11 sw out output 12 v in input supply voltage test circuit parts table symbol part name requirements c1 electrolytic capacitor 3000 f to 3300 f c2 electrolytic capacitor 2000 f to 2200 f c3 ceramic capacitor 1000pf l1 choke coil 90 h note: terminal capacitor for meas uring the ripple voltages: 0.1 f/50v film capacitor (tf capacitor) since pin (7) is grounded to the imst substrate, this may have an effect on noise and other factors if the heat sink is connected in the circuitry to the frame ground (fg), a gnd line, etc. in cases like th is, the heat sink must be floated or an insulating sheet must be used. pwm control circuit overcurrent protection circuit error amplifier drive circuit constant voltage circuit 2 constant voltage circuit 1 sub 6 gnd onf vadj v o ocp 2 3 4 5 7 1 v in sw out fwd 8 9 10 11 12 11 c3 l1 c2 c1 onf v o gnd v in gnd 12 9 10 7 85 63 41 2
STK755-030 no.a0295-4/7 evaluation board ? equivalent circuit ? pcb diagram silk screen pattern (seen from soldered side) circuit pattern (soldered side) ? parts table symbol part name require ments manufacturer remarks c1 electrolytic capacitor 3300 f/50v sanyo electric co., ltd. cz c2 electrolytic capacitor 2200 f/50v sanyo electric co., ltd. cz c5 ceramic capacitor 1000pf/50v mounted on soldered side l1 choke coil sk-24bs-110-100 toho zinc co., ltd. 90 h j1: jumper (10mm), j3: jumper (12.5mm) c3, c4, j2: none 11 c5 l1 c2 c1 onf v o gnd v in gnd 12 9 10 7 85 63 41 2 l1 c2 c3 c4 ic1 1 12 v in gnd +12v gn gnd onf j3 j1 j2 c1 stk755-020-a
STK755-030 no.a0295-5/7 sample characteristics at ta = 25 c, in the test circuit 12.3 11.8 11.7 05 3 12 6 478 output voltage - output current output current, i o - a output voltage, v o - v itf02439 12.0 12.2 12.1 11.9 v in =30v output voltage - input voltage input voltage, v in - v output voltage, v o - v i o =5a 100 50 40 05 3 12 6 478 efficiency - output current output current, i o - a efficiency, - % itf02440 70 90 80 60 v i n = 2 0 v 40v 30v 14 12 2 0 05 3 12 6 47 12 8 9 10 11 output overcurrent protection characteristics output current, i o - a output voltage, v o - v itf02441 6 10 8 4 v in =30v 12.3 11.8 11.7 itf02442 12.0 12.2 12.1 11.9 input current - input voltage input voltage, v in - v input current, i in - a i o = 7 a 5 a 5 1 0 15 35 20 25 30 40 45 15 35 20 25 30 40 45 itf02443 4 3 2 power dissipation - input voltage input voltage, v in - v power dissipation, ? p- w i o = 7 a 5 a 12 10 2 0 15 35 20 25 30 40 45 itf02444 8 6 4
STK755-030 no.a0295-6/7 use of an overvoltage pr otection circuit recommended generally, when constant-voltage power supply circuits have failed or are subject to defective soldering on pc boards, an overvoltage (which corresponds to the input voltage) may occur; that is to say, a voltage higher than the predetermined level is output. to minimize the damage and harm that an overvoltage can cause, the provision of an overvoltage protection circuit is therefore recommended. overvoltage protection circuit example dc input gnd output gnd constant-voltage power supply fuse scr zd cr 12.3 11.8 11.7 025 75 50 100 temperature characteristics: output voltage - ic substrate temperature ic substrate temperature, tc- c output voltage, v o - v itf02445 12.0 12.2 12.1 11.9 v in =30v 140 115 110 025 75 50 100 temperature characteristics: operating frequency - ic substrate temperature ic substrate temperature, tc- c operating frequency, fosc - khz itf02446 125 135 130 120 v in =30v
STK755-030 no.a0295-7/7 cut-off function: on/off control exercised over 12v output using an external signal on/off control circuit example when pin (1) is set to a low voltage, the 12v output is turned off. tr on ? 12v output off be absolutely sure to conduct the following checks at the design stage for products in which the STK755-030 will actually be used. 1) check the operation and effects of the output on/off control. 2) check that the changes in the ambien t temperatures of the devices, extraneous noise and other factors do not cause errors or trouble in operation. points to factor into the pattern design 1) connect the fwd pins (pins (8) and (9)) to the input capacitor (-). 2) ensure that the fwd pins (pins (8) and (9)) and the gnd pin (pin (7)) line are separate from one another. 3) connect the gnd pin (pin (7)) to th e input capacitor (-) or output capacitor (-). normally, it is connected to the output capacitor (-). 4) make the line between the input capacitor (-) and output capacitor (-) as short as possi ble. see the pcb diagram in the evaluation board for a concrete example. ps dc input gnd v o (12v) tr gnd STK755-030 circuit (7) (1) external input
|
