www.belling.com.cn 1 3a, 18v high efficiency synchronous step- down converter bl 9384 description the BL9384 is a wide input range, highefficiency, dc-to-dc step-down switching regulator, capable of delivering up to 3a of output current. current mode pwm control allows the use of small external components, such as ceramic input and output caps, as well as small inductors, while stil l providing low output ripples. on top of the integrated internal synchronous rectifier that eliminates external schottky diode, overall BL9384 is a highly efficient and robust solution for dc-dc step-down applications that requires wide input ranges. BL9384 is available esop8 packages. features wide input operating range from 4.5v to 18v capable of delivering 3a no external schottky diode needed current mode control 0.923v reference for low output voltages logic control shutdown thermal shutdown and uvlo available in esop8 package applications lcd tvs notebook computers fpga power supplies led drivers typical application pin out
www.belling.com.cn 2 BL9384 mark and ordering information mark explanation xx: year yy: week zz: internal code pinout description pin # name description 1 bst bootstrap pin. connect a 10nf capacitor from th is pin to sw 2 in supply voltage. bypass with a 22f ceramic capac itor to gnd 3 sw inductor connection. connect an inductor between sw and the regulator output. 4 gnd ground 5 fb feedback input. connect an external resistor divide r from the output to fb and gnd to set vout 6 comp regulator compensation. connect series rc netw ork to gnd. 7 en enable pin for the ic. drive this pin to high to enable the part, low to disable. 8 ss soft start pin. connect a 0.1 uf capacitor from this pin to gnd block diagram
www.belling.com.cn 3 BL9384 absolute maximum rating parameter value input voltage range -0.3v-20v sw, en voltage C0.3v to vin+0.3v bst voltage C0.3v to sw+6v fb voltage C0.3v to 6v sw to ground curren internally limited operating junction temperature(tj) -40 c C85 c package thermal resistance ( q jc) esop-8l 10 c / w storage temperature(ts) -40 c - 150 c note: exceed these limits to damage to the device. exposure t o absolute maximum rating conditions may affect device reliability. electrical characteristics (vin=12v, unless otherwise specified. typical value s are at t a =25 c) symbol parameter conditions min typ max unit vdd input voltage range 5 18 v uvlo_up uvlo,in uvlo rising rising, hysteresis=140m v 3.55 v vref feedback voltage 0.904 0.923 0.942 v ifb feedback leakage current 0.01 ua active, vfb=1v, no switching 1 ma iq quiescent current shutdown 6 ua error amp transconductance 800 s current sense transresistance 0.2 w fsoc switching frequency ven=2v, vin=12v 340 khz rdsonp pmos rdson 120 mohm rdsonn nmos rdson 100 mohm ilimit peak current limit 3.5 a ven en input low voltag 1 1.5 2 v ien en input current 1 a isw sw leakage current vin=12v,vsw=0 or 12v, en= gnd 10 a tsd over temperature proection 150 c
www.belling.com.cn 4 BL9384 typical performance characteristics (vin=12v, vout=3.3v, l=10uh, cin=10uf, cout=22uf, t a =25 c, unless otherwise stated) start - up waveform with slow vin 100ms/div v in v out i sw start-up waveform with fast vin 100ms/div load transient re sponse 200 m s/div v out i sw i sw v in v out 200mv/div 500ma/div 3a load switching waveform
www.belling.com.cn 5 BL9384 functional decriptions loop operation the BL9384 is a wide input range, high-efficiency, dc-to-dc step-down switching regulator, capable of delivering up to 3a of output current, integrated with a 110m w synchronous mosfet, eliminating the need for exter nal diode. it uses a pwm current-mode control scheme. an error amplifier integrates error between the fb signal and the int ernal reference voltage. the output of the integrator is then compa red to the sum of a current-sense signal and the sl ope compensation ramp. this operation generates a pwm signal that mo dulates the duty cycle of the power mosfets to achi eve regulation for output voltage. current limit there is a cycle-by-cycle current limit on the high -side mosfet of 3a(typ). when the current flowing o ut of sw exceeds this limit, the high-side mosfet turns off and the synchronous rectifier turns on. unlike the traditio nal method of current limiting by limiting the voltage at the com pensation pin, which usually has large variation du e to duty cycle variance, this type of peak current limiting scheme provides a relatively more accurate limit for outp ut current, thereby lowering the requirements for system design. component selectrion when setting up the BL9384 for different output vol tage, please use following recommended component va lue for the best performance. v out (v) c out ( m f) l ( m h) 8 22x2 22 5 22x2 15 3.3 22x2 10 2.5 22x2 6.8 1.8 22x2 4.7 1.2 22x2 3.3
www.belling.com.cn 6 BL9384 package outline package esop8 devices per reel 2500 unit mm package specification
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