datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 1 general description the PJ1509 is a of easy to use adjustable step - down (buck) switch - mode voltage regulator. the device is available in an adjustable output version. it is capable of driving a 2a load with excellent line and load regulation. requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation, and a fixed - frequency oscillator. t he output voltage is guaranteed to 3 % tolerance under specified input voltage and output load con ditions . the oscillator frequency is guaranteed to 1 5 %. external shutdown is included , featuring typically 5 0 a standby cur r ent . self protection features include a two stage frequency reducing current limit for the output switch and an over temperature s hutdown for complete protection under fault conditions . the PJ1509 is available in sop8 package. features ? adjustable output versions ? output adjustable from 1.23v to 34v ? fixed 150khz frequency internal oscillator ? guaranteed 2a output load c urrent ? input voltage range up to 45 v ? low power standby mode, i q typically 5 0 a ? ttl shutdown capability ? excellent line and load regulation ? high efficiency ? thermal shutdown and current limit protection ? available in advantaged sop8 packa ge applications ? simple high - efficiency step - down regulator ? on - card switching regulators ? positive to negative converter ? lcd monitor and lcd tv ? dvd recorder and pdp tv ? battery charger ? step - down to 3.3v for microprocessors package types sop8 figure 1. package types of PJ1509 free datasheet http:///
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 2 pin assignments pin descriptions ordering information pin name description 1 vin input supply voltage 2 output switching output 5~8 gnd ground 3 feedback output voltage feedback 4 on/off on/off shutdown active is ? low ? or floating sop8 x x PJ1509 circuit type package p: sop8 packing blank: tube r: type and reel
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 3 functional block diagram typical application figure 2. functional block diagram of PJ1509 figure 3. typical application of PJ1509
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 4 absolute maximum ratings note 1 : stresses greater than those listed under maximum ratings may cau se permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation is not implied. exposure to absolute maximum rating conditions for extended perio ds may affect reliability. parameter value unit supply voltage vin - 0.3 to 45 v feedback vfb pin voltage - 0.3 to vin+0.3 v on/off pin voltage - 0.3 to vin+0.3 v output pin voltage - 0.3 to vin+0.3 v output voltage to ground (steady state) - 1 v power d issipation internally limited w operating temperature range - 40 to +125 o c storage temperature - 65 to + 150 o c lead temperature (soldering, 10 sec) 200 o c esd( h m) 2000 v electrical characteristics u nless otherwise specified , v in = 12v . iload = 0.5a, ta = 25 ?? . symbol parameter conditions min. typ. max. uni t i b feedback bias current v fb =1.3v 10 50/ 100 na i q quiescent current v fb =12v force driver off 5 10 ma i stby standby quiescent current on/off=5v, v in = 45 v 50 100 ua f osc oscillator frequency 221 260 299 khz v sat saturation voltage i out =2a 1.10 1.3 v i cl current limit peak current (v fb =0v) 3.8 a output leakage current output=0v (v fb =12v) 50 ua i l i l output leakage current output= - 1v (v in =32v) 2 30 ma low (regulator on) 1.3 0.6 v v il v ih on/off pin logic input threshold voltage high (regulator off) 2.0 1.3 v i h on/off pin input current v logic =2.5v(regulator off) 5 15 ua
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 5 i l v logic =0.5v(regulator on) 0.02 5 ua | jc thermal resistance junction to case sop8 10 o c/ w | ja thermal resistance junction to ambient (note1) sop8 40 o c/ w vfb: output voltage 11v ? v in ? 32v, 0.2a ? i load ? 2a, v out for 9v 1.193/ 1.180 1.23 1.267/ 1.280 v PJ1509 adj |? : efficiency v in =12v,v out = 9v,i load =2a 89 % specifications with boldface type are for full operationg temperature range, the other type are for t j =25 o c. note1: thermal resistance with copper area of approximately 3 in 2 .
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 6 typical performance characteristics figure 4 . output voltage vs. temperature figure 5 . switching frequency vs. temperature figure 6 . output saturation characteristics figure 7 . quiescent current vs. temperature
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 7 figure 8 . on/off pin voltage figure 9 . on/off pin sink current figure 10 . output saturation characteristics
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 8 typical application circuit (adjustable output voltage version) vout r1 r2 cf (operational) 3.3v 1.6k 2.7k 33nf 5v 3.6k 11k 10nf 9v 6.8k 43k 1.5nf 12v 1.5k 13k 1nf output capacitor (cout) output voltage input voltage inductor (l1 ) through hole electrolytic 6v ~ 18v 47uh 470uf/25v 3.3v 6v ~ 45 v 68uh 560uf/25v 8v ~ 18v 33uh 330uf/25v 5v 8v ~ 45 v 47uh 470uf/25v 12v ~18v 47uh 330uf/25v 9v 12v ~ 45 v 47uh 470uf/25v 15v ~ 18v 47uh 220uf/25v 12v 15v ~ 45 v 47uh 330uf/25v figure 1 1. typical application of PJ1509 table 1. vout vs. r1, r2, cf select table table 2. typical application buck regulator design procedure
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 9 function description pin functions +v in this is the positive input supply for the ic switching regulator. a suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator ground circuit ground. output internal switch. the voltage at this pin switches between (+v in ? v sat ) and approximately ? 0.5v, with a duty cycle of approximately v out / v in . to minimize coupling to sensitive circuitry, t he pc board copper area connected to this pin should be kept a minimum. feedback senses the regulated output voltage to complete the feedback loop. on/off allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 50 ua. pulling this pin below a threshold voltage of approximately 1.3v turns the regulator on, and pulling this pin above 1.3v (up to a maximum of 3 2v) shuts the regulator down. if this shutdown feature is not ne eded, the on /off pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the on condition . thermal considerations the PJ1509 is available in sop8 package. the sop8 package needs a heat sink under most con ditions. the size of the heat sink d epends on the input voltage, the output voltage, the load current and the ambient temperature. the PJ1509 junction temperature rises above ambient temperature for a 2a load and different input and output voltages. the da ta for these curves was taken with the PJ1509 (sop8 package) operating as a buck - switching regulator in an ambient temperature of 25 o c (still air). these temperature rise numbers are all approximate and there are many factors that can affect these temperat ures. higher ambient temperatures require more heat sinking. for the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (once exception to this is the output (switch) pin, which should not have large areas of copper.) large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further. package thermal resistance and junction te mperature rise numbers are all approximate, and there are many factors that will affect these numbers. some of these factors include board size, shape, thickness, position, location, and even board temperature. other factors are, trace width, total printed circuit copper area, copper thickness, single or double - sided, multi - layer board and the amount of solder on the board. the effectiveness of the pc board to dissipate heat also depends on the size, quantity and spacing of other components on the board, a s well as whether the surrounding air is still or moving. furthermore, some of these components such as the catch diode will add heat to the pc board and the heat can vary as the input voltage changes. for the inductor, depending on the physical size, type of core material and the dc resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board.
datasheet 2 a 150khz pwm buck dc/dc converter PJ1509 october, 20 , 2005. 10 package information sop8 package outline dimensions
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