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product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 1 synchronous 600 ma step - down dc/dc c onverter features ? built - in transistors ? operating input voltage range : 2.0 v ~ 6 .0 v (a/b/c types) or 1.8 v ~ 6.0 v (d/e/f/g types) ? output voltage range externally set : 0 .8 v ~ 4.0 v (internally set) or 0.9 ~ 6.0 v (externally set) ? output current : 600 m a ? high efficiency : 92 % ? oscillation frequency : 1.2 m hz , 3 mhz ? maximum duty cycle : 100 % ? operating modes : pwm, pwm/pfm auto select or pwm/pfm manual select ? functions: build - in current limit, load capacitor discharge, high speed soft start ? operating ambient temperature: - 40 ~ +85 0 c ? package s : sot - 25, usp - 6c, usp - 6el, wlp - 5 - 03 ? eu rohs compliant, pb free application ? mobile phones ? bluetooth headsets ? digital home appliance s ? office automation equipment ? various portable equipment description the ixd3 235 / 36/37 series is a group of synchronous - rectification type dc/dc converters with a built - in 0.52 n - channel synchronous rectification transistor and 0.42 p - channel switching transistor providing up to 600 ma output current. operating voltage range is from 2.0 v to 6.0 v (a c types) or 1.8 v to 6.0 v (d g types). for the d/f types, which have a reference voltage of 0.8 v with 2.0% accuracy, the output voltage can be set from 0.9 v by using two external resistors. the a/b/c/e/g types have a fixed output voltage from 0.8 v to 4.0 v in increments of 0.05 v with 2.0% accuracy . the device requires only a n inductor and two externally connected ceramic capacitors. t he built - in oscillator, either 1.2 mhz or 3.0 mhz , can be selected. t he ixd3 235 operates in pwm mode , the ixd3 236 automatic ally switches between pwm/pfm modes, and the ixd3 237 allows switch manually between the pwm and the automatic pwm/pfm switching control mode s. this allow s fast response, low ripple, and high efficiency over the full range of loads from light to heavy . the soft start and current control functions are internally optimized. a ll circuits are disabled in a standby mode to reduce current consumption to less than 1.0 a. the b/f/g types have a 0.25 ms high - speed soft - start for quick turn - on. t he built - in unde r voltage lock o ut ( uvlo ) function forces the internal p - channel transistor off , when input voltage becomes 1.4 v or lower. the b to g types have the output capacitor c l discharge circuitry, which allows fast c l discharge when ic goes into standby mode. device is available in f our types of package s: sot - 25, usp - 6c, usp - 6el , and wlp - 5 - 03. typical application circuit s typical performance characteristic IXD3235/36/37 a, b, c, e, and g types IXD3235/36/37 d and f types efficiency vs. output current (f osc = 1.2 mhz, v out = 1.8 v) pwm/pfm automatic switching mode
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 2 absolute maximum rat ings parameter symbol ratings units v in pin voltage v in C 0.3 ~ 6.5 v l x pin voltage v lx C 0.3 ~ v in + 0.3 1 v v out pin voltage v out C 0.3 ~ 6.5 v fb pin voltage v fb C 0.3 ~ 6.5 v ce/mode pin voltage v ce C 0.3 ~ 6.5 v lx pin current i lx 1500 m a power dissipation sot - 25 p d 250 mw usp - 6c 120 usp - 6el 120 wlp - 5 - 03 750 operating temperature range t opr C 40 ~ + 8 5 0 c storage temperature range t stg C 5 0 ~ +125 0 c electrical operating characteristics IXD3235/36/37 a series , v out = 1.8 v, ta = 25 0 c parameter symbol conditions min. typ. max. unit circuit operating voltage range v in 2.0 - 6.0 v ? output voltage v out v in = v ce = 5.0 v, i out = 30 ma 1.764 1.800 1.836 v maximum output current i out_max v in = v out(e) + 2.0 v, v ce = 1.0 v 9) 600 m a ? uvlo voltage v uvlo v ce = v in , v out = 0 1) , 11) 1.00 1.40 1.78 v ? supply current ixd323xa18cxx i q v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 15 33 a ? ixd323xa18dxx 21 35 standby current i stb v in = 5.0 v, v ce = 0 v, v out = v out(e) x 1.1 v 0 1.0 a ? oscillation frequency ixd323xa18cxx f osc v in = v out(e) + 2 v, v ce = 1.0 v, i out = 100 ma 1020 1220 1380 khz ? ixd323xa18dxx 2550 3000 3460 pfm switching current ixd323xa18cxx i pfm 12) v in = v ce = v out(e) + 2 v, , i out = 1 ma (see table a) 120 160 200 ma ixd323xa18dxx 170 220 270 p - channel on time maximum t pon_max 12) v in = v ce = ( see table b ), i out = 1 ma 2d max 3d max maximum duty cycle ratio d max v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 100 % ? m in imum duty cycle ratio d m in v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 0 % ? efficiency 2) ixd323xa18cxx effi v in = v ce = v out(e) + 1.2 v, i out = 100 ma 92 % ? ixd323xa18dxx 86 l x h on resistance 1 3) r lxh 1 v in = v ce = 5.0 v, v out = 0 v, i lx = 100 ma 0.35 0.55 ? ? l x h on resistance 2 3) r lxh 2 v in = v ce = 3.6 v, v out = 0 v, i lx = 100 ma 0.42 0.67 ? ? l x l on resistance 1 4) r lxl 1 v in = v ce = 5.0 v 0.45 0.65 ? ? l x l on resistance 2 4) r lxl 2 v in = v ce = 3.6 v 0.52 0.77 ? ? l x h leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? l x l leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? current limit 10) i lim v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 8) 900 1050 1350 ma output voltage temperature characteristics - 40 0 c t opr 8 5 0 c , i out = 30 ma 10 0 ppm/ 0 c ? ce h voltage 14) v ce h v out = 0 v 0.65 6.0 v ? ce l voltage 1 5) v ce l v out = 0 v 0 0.2 5 v ? pwm mode start voltage 6), 13) v pwm i out = 1 ma v in - 1.0 p w m /pfm mode start voltage 6), 13) v pfm i out = 1 ma v in C 0.25 ce h current i enh v in = v ce = 5.0 v, v out = 0 v - 0.1 0.1 a ?
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 3 ce l current i enl v in = 5.0 v, v ce = 0 v, v out = 0 v - 0.1 0.1 a ? soft - start time ixd323xa18cxx t ss i out = 1 ma (see table c) 0.5 1.0 2.5 ms ? ixd323xa18dxx 0.5 0.9 2.5 latch time 7) t lat v in = v ce = 5.0 v, v out = 0.8 x v out(e) , l x short with 1 ? resistor to ground 1.0 20.0 ms short protection threshold voltage v short v in = v ce = 5.0 v, l x short with 1 ? resistor to ground 0.675 0.900 1.150 v note: test conditions: unless otherwise stated, v in = 5.0 v, v out(e) = nominal voltage 1) including hysteresis operating voltage range 2) effi = { ( output voltage output current) / (input voltage input current)} 100 % 3) on resistance ( ) = (v in - lx pin measurement voltage) / 100ma 4) design target value 5) a 10 a (maximum) current may leak at high temperature 6) the ce/mode pin of the ixd3 237a series functions also as an external switching pin between pwm and pwm/pfm control . c ontrol is switched to the automatic pwm/pfm switching mode when the ce/mode pin voltage is equal to or greater than v in minus 0.3 v, and to the pwm mode when the ce/mode pin voltage is equal to or lower than vin minus 1.0v . however, it should be equal to or greater than v ceh 7) time f rom moment when v out is shorted to gnd via 1 resistor to the moment, when c urrent l imit generates pulse stopping l x oscillations 8) when v in is less than 2.4 v, current limit may not be reached because of voltage drop across on resistance 9) when the difference between input and output voltage is small, some cycles may be skipped completely before current maximizes. if load current increases in this state, output voltage will decrease because of the voltage drop across p - channel transistor 10) current limi t denotes the level of an inductor peak current 11) voltage, when l x pin voltage is l=+0.1 v ~ - 0.1 v 12) not for ixd3 235 series , because they have pwm mode only 13) t he ixd3 237 series only 14) voltage at which l x pin state changes from l to h = v in ~ v in - 1.2 v 15) voltage at which l x pin state changes from h to l =+0.1 v ~ - 0.1 v
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 4 electrical operating characteristics (continued) IXD3235/36/37 b/c/e/g series, v out = 1.8 v, ta = 25 0 c parameter symbol conditions min. typ. max. unit circuit operating voltage range b/c series v in 2.0 - 6.0 v ? e/g series 1.8 6.0 output voltage v out v in = v ce = 5.0 v, i out = 30 ma 1.764 1.800 1.836 v maximum output current i out_max v in = v out(e) + 2.0 v, v ce = 1.0 v 9) 600 m a ? uvlo voltage v uvlo v ce = v in , v out = v out(e) x 0.5 v 1) , 11) , 16) 1.00 1.40 1.78 v ? supply current ixd323x x 18cxx i q v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 15 33 a ? ixd323x x 18dxx 21 35 standby current i stb v in = 5.0 v, v ce = 0 v, v out = v out(e) x 1.1 v 0 1.0 a ? oscillation frequency ixd323x x 18cxx f osc v in = v out(e) + 2 v, v ce = 1.0 v, i out = 100 ma 1020 1220 1380 khz ? ixd323x x 18dxx 2550 3000 3460 pfm switching current ixd323x x 18cxx i pfm 12) v in = v ce = v out(e) + 2 v, , i out = 1 ma (see table a) 120 160 200 ma ixd323x x 18dxx 170 220 270 p - channel on time maximum t pon_max 12) v in = v ce = (see table b ), i out = 1 ma 2d max 3d max maximum duty cycle ratio d max v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 100 % ? m in imum duty cycle ratio d m in v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 0 % ? efficiency 2) ixd323xx18cxx effi v in = v ce = v out(e) + 1.2 v, i out = 100 ma 92 % ? ixd323x x 18dxx 86 l x h on resistance 1 3) r lxh 1 v in = v ce = 5.0 v, v out = 0 v, i lx = 100 ma 0.35 0.55 ? ? l x h on resistance 2 3) r lxh 2 v in = v ce = 3.6 v, v out = 0 v, i lx = 100 ma 0.42 0.67 ? ? l x l on resistance 1 4) r lxl 1 v in = v ce = 5.0 v 0.45 0.65 ? ? l x l on resistance 2 4) r lxl 2 v in = v ce = 3.6 v 0.52 0.77 ? ? l x h leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? l x l leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? current limit 10) i lim v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 8) 900 1050 1350 ma output voltage temperature characteristics - 40 0 c t opr 8 5 0 c , i out = 30 ma 10 0 ppm/ 0 c ? ce h voltage 14) v ce h v out = 0 v 0.65 6.0 v ? ce l voltage 1 5) v ce l v out = 0 v 0 0.2 5 v ? pwm mode start voltage 6), 13) v pwm i out = 1 ma v in - 1.0 pwm/pfm mode start voltage 6), 13) v pfm i out = 1 ma v in C 0.25 ce h current i enh v in = v ce = 5.0 v, v out = 0 v - 0.1 0.1 a ? ce l current i enl v in = 5.0 v, v ce = 0 v, v out = 0 v - 0.1 0.1 a ? soft - start time ixd323xb(g)18cxx t ss i out = 1 ma (see table c) 0.25 0.4 ms ? ixd323xc(e)18cxx 0.5 1.0 2.5 ixd323xb(g)18dxx 0.32 0.50 ixd323xc(e)18dxx 0.5 0.9 2 . 5 latch time 7) t lat v in = v ce = 5.0 v, v out = 0.8 x v out(e) , l x short with 1 ? resistor to ground 1.0 20.0 ms short protection threshold voltage b/c series v short v in = v ce = 5.0 v, l x short with 1 ? resistor to ground 0.675 0.900 1.150 v e/g series 0.338 0.450 0.563 c l discharge resistance r dcl v in = v lx = 5.0 v, v ce = 0 v, v out - open 200 300 450 ? note: test conditions: unless otherwise stated, v in = 5.0 v, v out(e) = nominal voltage 1) including hysteresis operating voltage range 2) effi = { ( output voltage output current) / (input voltage input current)} 100 % 3) on resistance ( ) = (v in - lx pin measurement voltage) / 100ma 4) design target value
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 5 5) a 10 a (maximum) current may leak at high temperature 6) the ce/mode pin of the ixd3 237a series functions also as an external switching pin between pwm and pwm/pfm control . c ontrol is switched to the automatic pwm/pfm switching mode when the ce/mode pin voltage is equal to or greater than v in minus 0.3 v, and to the pwm mode when the ce/mode pin voltage is equal to or lower than vin minus 1.0v . however, it sh ould be equal to or greater than v ceh 7) time from moment when v out is shorted to gnd via 1 resistor to the moment, when current limit generates pulse stopping l x oscillations 8) when v in is less than 2.4 v, current limit may not be reached because of voltage drop across on resistance 9) when the difference between input and output voltage is small, some cycles may be skipped completely before current maximizes . if load current increases in this state, output voltage will decrease because of the voltage drop acros s p - channel transistor 10) current limit denotes the level of an inductor peak current 11) voltage, when l x pin voltage is l=+0.1 v ~ - 0.1 v 12) not for ixd3 235 series , because they have pwm mode only 13) t he ixd3 237 series only 14) voltage at which l x pin state changes from l to h = v in ~ v in - 1.2 v 15) voltage at which l x pin state changes from h to l =+0.1 v ~ - 0.1 v 16) voltage at which v out becomes more than v in , while v in is rising from 0 v to v out (e) x 0.5 v
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 6 electrical operating characteristics (continued) IXD3235/36/37 d/f series, v out = 1.8 v, ta = 25 0 c parameter symbol conditions min. typ. max. unit circuit operating voltage range v in 1.8 - 6.0 v ? fb voltage v fb v in = v ce = 5.0 v, i out = 30 ma 1.784 1.800 1.816 v maximum output current i out_max v in = v out(e) + 2.0 v, v ce = 1.0 v 9) 600 m a ? uvlo voltage v uvlo v ce = v in , v out = 0 1) , 11) 1.00 1.40 1.78 v ? supply current ixd323x x 18cxx i q v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 15 a ? ixd323x x 18dxx 21 35 standby current i stb v in = 5.0 v, v ce = 0 v, v out = v out(e) x 1.1 v 0 1.0 a ? oscillation frequency ixd323x x 18cxx f osc v in = v out(e) + 2 v, v ce = 1.0 v, i out = 100 ma 1020 1220 1380 khz ? ixd323x x 18dxx 2550 3000 3460 pfm switching current ixd323x x 18cxx i pfm 12) v in = v ce = v out(e) + 2 v, , i out = 1 ma (see table a) 120 160 200 ma ixd323x x 18dxx 170 220 270 p - channel on time maximum t pon_max 12) v in = v ce = (see table b ), i out = 1 ma 2d max 3d max maximum duty cycle ratio d max v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 100 % ? m in imum duty cycle ratio d m in v in = v ce = 5.0 v, v out = v out(e) x 1.1 v 0 % ? efficiency 2) ixd323x x 18cxx effi v in = v ce = v out(e) + 1.2 v, i out = 100 ma 92 % ? ixd323x x 18dxx 86 l x h on resistance 1 3) r lxh 1 v in = v ce = 5.0 v, v out = 0 v, i lx = 100 ma 0.35 0.55 ? ? l x h on resistance 2 3) r lxh 2 v in = v ce = 3.6 v, v out = 0 v, i lx = 100 ma 0.42 0.67 ? ? l x l on resistance 1 4) r lxl 1 v in = v ce = 5.0 v 0.45 0.65 ? ? l x l on resistance 2 4) r lxl 2 v in = v ce = 3.6 v 0.52 0.77 ? ? l x h leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? l x l leakage current 5) i lxh v in = v ce = 5.0 v, v out = 0 v, v lx = 5.0 v 0.01 1.0 a ? current limit 10) i lim v in = v ce = 5.0 v, v out = v out(e) x 0.9 v 8) 900 1050 1350 ma output voltage temperature characteristics - 40 0 c t opr 8 5 0 c , i out = 30 ma 10 0 ppm/ 0 c ? ce h voltage 14) v ce h v out = 0 v 0.65 6.0 v ? ce l voltage 1 5) v ce l v out = 0 v 0 0.2 5 v ? pwm mode start voltage 6), 13) v pwm i out = 1 ma v in - 1.0 pwm/pfm mode start voltage 6), 13) v pfm i out = 1 ma v in C 0.25 ce h current i enh v in = v ce = 5.0 v, v out = 0 v - 0.1 0.1 a ? ce l current i enl v in = 5.0 v, v ce = 0 v, v out = 0 v - 0.1 0.1 a ? soft - start time ixd323xd18cxx t ss i out = 1 ma (see table c) 0.5 1.0 2.5 ms ? ixd323xf18cxx 0.25 0.40 ixd323xd18dxx 0.5 1.0 2.5 ixd323xf18dxx 0.25 0.40 latch time 7) t lat v in = v ce = 5.0 v, v out = 0.8 x v out(e) , l x short with 1 ? resistor to ground 1.0 20.0 ms short protection threshold voltage v short v in = v ce = 5.0 v, l x short with 1 ? resistor to ground 0.675 0.900 1.150 v c l discharge resistance r dcl v in = v lx = 5.0 v, v ce = 0 v, v out - open 200 300 450 ? note: test conditions: unless otherwise stated, v in = 5.0 v, v out(e) = nominal voltage 1) including hysteresis operating voltage range 2) effi = { ( output voltage output current) / (input voltage input current)} 100 % 3) on resistance ( ) = (v in - lx pin measurement voltage) / 100ma 4) design target value 5) a 10 a (maximum) current may leak at high temperature
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 7 6) the ce/mode pin of the ixd3 237a series functions also as an external switching pin between pwm and pwm/pfm control . c ontrol is switched to the automatic pwm/pfm switching mode when the ce/mode pin voltage is equal to or greater than v in minus 0.3 v, and to the pwm mode when the ce/mode pin voltage is equal to or lower than vin minus 1.0v . however, it should be equal to o r greater than v ceh 7) time from moment when v out is shorted to gnd via 1 resistor to the moment, when current limit generates pulse stopping l x oscillations 8) when v in is less than 2.4 v, current limit may not be reached because of voltage drop across on resistance 9) when the difference between input and output voltage is small, some cycles may be skipped completely before current maximizes . if load current increases in this state, output voltage will decrease because of the voltage drop across p - channel transistor 10) current limit denotes the level of an inductor peak current 11) voltage, when l x pin voltage is l=+0.1 v ~ - 0.1 v 12) not for ixd3 235 series , because they have pwm mode only 13) t he ixd3 237 series only 14) voltage at which l x pin state changes from l to h = v in ~ v in - 1.2 v 15) voltage at which l x pin state changes from h to l =+0.1 v ~ - 0.1 v table a pfm switching current (i pfm ) vs. oscillation frequency and setting voltage setting voltage f osc = 1.2 mhz f osc = 3.0 mhz min typ max min typ max v out(e ) 1.2 v 140 180 240 190 260 350 1.2 v < v out(e ) 1.75 v 130 170 220 180 240 300 v out(e ) 1.8 v 120 160 200 170 220 270 table b input voltage (v in ) for measuring p - channel on time maximum t pon_max f osc 1,2 mhz 3 mhz v in v out(e ) + 0.5 v v out(e ) +1.0 v note: example: w hen v out(e) = 1.2v and f osc = 1.2 mhz, v in should be 1.7 v, however, v in should be at least 2 .0 v if the minimum operating voltage is 2.0 v table c soft - start time vs. setting voltage and oscillation frequency (IXD3235/36/37 b and g series only series f osc setting voltage, v soft start time, s min typ max IXD3235b/g ixd3237b/g 1.2 mh z 0.8 v out(e) < 1.75 250 400 1.5 v out(e) < 1.8 320 500 1.8 v out(e) < 2.5 250 400 2.5 v out(e) < 4.0 320 500 ixd3236b/g 0.8 v out(e) < 2.5 250 400 2.5 v out(e) < 4.0 320 500 IXD3235/36/37 b/g 3.0 mh z 0.8 v out(e) < 1.8 250 400 1.8 v out(e) < 4.0 320 500
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 8 pin configura tion sot - 25 (top view) usp - 6c (bottom view) usp - 6el (bottom view) wlp - 5 - 03 (bottom view) note: the dissipation pad for the usp - 6c and usp - 6el package s should be soldered in recommended mount pattern and metal masking to enhance mounting strength and heat release. if the pad needs to be connected to other pins, it should be connected to the v ss (no 2 and no 5) pin s . v ss pins (no. 2 and 5) should be tied together. pin assignment pin number pin name functions sot - 25 usp - 6c/usp - 6el wlp - 5 - 03 1 6 2 v in power input 2 2, 5 3 v ss ground 3 4 1 ce/mode enable (active high), mode selection pin 4 3 4 v out (fb) fixed output voltage - a/b/c/e/g series (output voltage sense pin - d/f series) 5 1 5 l x switching node
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 9 block diagram s IXD3235/36/37 a series IXD3235/36/37 b/c/e/g series IXD3235/36/37 d/f series internal diodes include an esd protection and a parasitic diode basic operation the ixd3 235/36/37 series consists of a r eference v oltage source, r amp w ave generator , e rror a mplifier, pwm c omparator, p hase c ompensation circuit, output voltage resist ive divider , p - channel switching transistor, n - channel transistor for the synchronous switch, c urrent l imiter circuit, uvlo circuit , and others. (see the block diagram above.) the error amplifier compares output voltage divid ed by internal (external for d/f versions) resistors r fb1 /r fb2 with the internal reference voltage. amplified difference between these two signals applies to the one input of the pwm comparator, while ramp voltage from the ramp wave generator applies to th e second input. resulting pwm pulse determines switching transistor on time. it goes through the buffer and it appears at the gate of the in ternal p - channel switching transistor . this continuous process stabilizes output voltage. the current feedback circ uit monitors current of the p - channel transistor at each switching cycle, and modulates output signal from the error amplifier to provide additional feedback. this guarantees a stable converter operation even with low esr ceramic load capacitor. reference voltage source the r eference v oltage s ource provides the reference voltage to ensure stable output voltage of the dc/dc converter. ramp wave generator the r amp w ave generator produce s ramp waveform signal needed for pwm operation, and signals to synchroniz e all the internal circuits. it operates at internally fixed 1.2 mhz or 3.0 mhz frequency.
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 10 error amplifier the e rror a mplifier monitor s output voltage through resistive divider connected to v out (fb) pin . if output voltage falls below preset value and er ror amplifiers input signal becomes less than internal reference voltage , t he error amplifier/s output signal increases . that results in wider pwm pulse and respectively longer on time for switching transistor to increase output voltage. the gain and freq uency characteristics of the error amplifier output are fixed internally to optimize ic performance. current limit er the c urrent l imiter circuit monitors current flowing through the p - channel transistor connected to the lx pin, and comb i ne s function of the current limit and operation suspension. when transistors current is greater than a specifi ed level, the c urrent l imit er turn s off p - channel transistor immediately. after that , the current l imiter turns off too, returning to monitoring mode . t he driver tr ansistor turn s on a t the next cycle , but the current limiter will turn it off immediately i f an over current exists . when the over current state is eliminated, the ic resumes its normal operation. the ic waits for end of the over current state repeating above steps (t1 on figure below) . if an over - current state continues for a few ms with ic repeatedly perform ing above steps , the current limiter latch es the p - channel transistor in off state, an d ic suspen ds operations (t2 on figure below) . to restart ic o peration after this condition , either en pin should be toggled h C l C h, or v in pin voltage should be set below uvlo to resume operations from soft start. the suspension mode is not a standby mode. in t he suspension mode , pulse output is suspended; howeve r , internal circuitries remain in operation mode consuming power. short - circuit protection the short - circuit protection monitors the r fb1 / r fb 2 divider voltage (fb point in the block diagram). if output is accidentally shorted to the g round , fb voltage starts falling. when this voltage becomes less than half of the reference voltage (v ref ) and p - channel switching transistors current is more than the i lim threshold, the s hort - c ircuit p rotection turn s off and latch es quickly the p - channel tra nsistor. at d/e/f/g series , short circuit protection starts once fb voltage become s less than 0.25 of reference voltage (v ref ), disregard to transistors current. to restart ic operation after this condition , either en pin should be toggled h C l C h, or v in pin voltage should be set below uvlo to resume operations from soft start. the sharp load transient s creat ing a voltage drop at the v out , propagate to the fb point through c fb , that may result in s hort c ircuit protection operat ing at voltage s higher tha n 1/2 v ref voltage. uvlo circuit when the v in pin voltage becomes 1.4v or lower, the p - ch annel transistor is forced off to prevent false pulse output caused by unstable operation of the internal circuitry. when the v in pin voltage becomes 1.8 v or higher, switching operation s resume with the soft start . the soft start function operates even when the v in voltage falls
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 11 below the uvlo threshold for a very short time . the uvlo circuit does not cause a complete shutdown of the ic, but causes pulse output to be s uspended; therefore, the internal circuitry remains in operation. pfm switch current in pfm mode , the ic keeps the p - ch annel transistor on until inductor current reaches a specified level (i pfm ) . p - channel transistors on time is equal t on = l i pfm / (v in - v out ) , s, where l is an inductance in h, and i pfm is a current limit in a. pfm duty limit in pfm mode , p - channel on time maximum ( t pon_max ) is set to 2d max , i.e. two periods of the switching frequency. t herefore, under condition s, when the on time increases ( i.e. step - down ratio is small), it is possible that p - ch annel transistor to be turned off , even when inductor current does n o t reach to i pfm . ( see figures 1 and 2 below ) figure 1 figure 2 c l high speed discharge the ixd3 235 / 36 / 37 b , c , d, e , f , and g series can quickly discharge the output capacitor (c l ) to avoid application malfunction , when ce pin set logic low to disable ic. c l discharge t ime is proportional to the resistance (r) of the n - ch annel transistor located between the l x pin and ground a nd the output c l capacitance as shown below . t dsh = rc l x ln (v out(e) / v) , where v - output voltage after discharge v out(e) - output voltage r = 300 ( t ypical value output voltage discha r ge characteristics
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 12 ce/mode pin function the ixd3 235 / 36/37 series enter the shut down mode , when a low logic - level signal applies to the ce/mode pin. in the shutdown mode, ic current consumption is ~ 0 a (t ypical value ), with the lx and v out pin s at high impedance state . the ic starts its operation w hen a high logic - level signal applies to the ce/mode pin. intermediate voltage , generated by external resistive divider can be used to select pwm/pfm auto or pwm only switching modes in respect with the table below. ce/mode voltage level operation mode IXD3235 ixd3236 ixd3537 0.65 v v ce/mode 6.0 v synchronous fixed pwm mode synchronous pwm/pfm auto switching mode - v in C 0.25 v v ce/mode v in - - synchronous pwm/pfm auto switching mode 0.65 v v ce/mode v in C 1.0 v - - synchronous fixed pwm mode 0 v v ce/mode 0.25 v standby mode standby mode standby mode examples of ce/mode pin use are shown below. please set the value of each resistor from few hundreds k to few hundred m . for switches, cpu open - drain i/o port and transistor can be used. the ce/mode pin is a cmos input with a sink current ~ 0 a. ixd3 235/36 series - examples of how to use ce/mode pin sw - ce position ic status schematic a schematic b on standby active off active standby ixd3 237 series - examples of how to use ce/mode pin sw - ce position sw - pwm/pfm position ic status schematic a schematic b on x standby pwm/pfm auto switching mode off on pwm mode pwm mode off off pwm/pfm auto switching mode standby soft start soft start time is available in two options via product selection. the soft - start time of ixd32 35/36/37 series is optimized by using internal circuits and it is 1.0 ms (typ ically .) for a/c/d/e series and 0.25 ms for b/f/g series . d and f series require external resist o rs and a capacitor to set the output voltage, so the soft - start time might vary based on value of those external components. the definition of the soft - start time is the time when the output voltage goes up to the 90% of nominal output voltage after the ic is enabled by ce h signal.
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 13 typical application circuit s IXD3235/36/37 a, b, c, e, g series (fixed output voltage) IXD3235/36/37 d, f series (adjustable output voltage) external componen ts f osc 1.2 mhz 3.0 mhz l, h 4.7 1.5 c in , f 4.7 4.7 c l , f 10 10 setting output voltage the IXD3235/36/37 d, f series allows set o utput voltage externally by two resistors r fb1 and r fb2 as sown on schematic diagram above. output voltage can be set starting from 0.9v. however, when input voltage (v in ) is lower than the set output voltage, output voltage (v out ) cannot be higher than the input voltage. v out = 0.8 (r fb1 +r fb2 )/r fb2 r fb1 + r fb2 < 1 m. the value of the phase compensation capacitor c fb is calculated by the follow equation f zfb = 1/(2 c fb r fb1 ) , w here f zfb < 10 khz. for optimization, f zfb can be adjusted in the range of 1 khz to 20 khz depending on the inductance l and the load capacitance c l . example: when r fb1 = 470 k and r fb2 = 150 k, v out = 0.8 (470 k+150 k) / 150 k = 3.3 v v out , v r fb1 , k r fb2 , k c fb , pf v out , v r fb1 , k r fb2 , k c fb , pf 0.9 100 820 150 2.5 510 240 100 1.2 150 300 100 3.0 330 120 150 1.5 130 150 220 3.3 470 150 100 1.8 300 240 150 4.0 120 30 470
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 14 layout and use considerations 1. wire external components as close to the ic as possible and use thick, short connecting traces to reduce the circuit impedance. please, pay special attention to the v in and gnd wiring. switching noise, which occurs from the gnd, may c ause the instability of the ic, so, position v in and v c l capacitors as close to ic as possible. 2. t ransitional voltage drop s or voltage rising phenomenon could make the ic unstable if ratings are exceeded . 3. the ixd3 235/36/37 series are designed to work with ceramic output capacitors. h owever, i f the difference between input and output voltage s is too high , a ceramic capacitor may fail to absorb the resulting high switching energy and oscillation could occur. in this case, c onnect an electrolytic capacitor in parallel to ceramic one to compensate for insufficient capacitance . 4. i n pwm mode , ic generates very narrow pulses, and there is a possibility that some cycles will be skipped completely , if the difference between v in and v out is high. 5. if the difference between v in and v out is small, ic generat es very wide pulses , and there is a possibility that some cycles will be skipped completely at the heavy load current. 6. w hen dropout voltage or load current is high, c urrent l imit may activate prematurely that will lead to ic instability. to avoid this cond ition, choose inductors value to set peak current below current limit threshold. c alculate the peak current according to the following formula: i pk = (v in - v out ) x d / (2 x l x f osc ) + i out , where l - inductance f osc - - oscillation frequency d C duty cycle 7. inductors rated current should exceed current limit threshold to avoid damage, which may occur until p - channel transistor turns off after current limiter activates (see figure below) . ? current flows into p - channel transistor reaches the current limit (i lim ). ? c urrent is more than i lim due the circuits delay time from the current limit detection to the p - channel transistor off. ? the inductors current time rate becomes quite small . ? ic generates v ery narrow pulses for several m illiseconds . ? the circuit latches, stopping operation. 8. if v in voltage is less than 2.4 v, c urrent limit threshold may be not reached due voltage drop caused by switching transistors on resistance 9. l atch time may become longer or latch may not work due electrical noise . t o avoid this effect, the board should be laid out so that input capacitors are placed as close to the ic as possible . 10. use of the ic at voltages below recommended voltage range may lead to instability . 11. at high temperature, o utput voltage may increase up to input voltage level at no load , because of the leak age current of the driver transistor . 12. high step - down ratio and very light load may be cause of intermittent oscillations. 13. in pwm/pfm automatic switching mode, ic may become unstable during transition to continuous mode. please verify with actual components.
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 15 v out = 3.3 v, f osc = 1.2 mhz, v in = 3.7 v, i out = 100 ma ch 1 C v lx C 5 v/div ; c h 2 C v out C 2.0 mv/div external components: l = 4.7 h (np4018) cin = 4.7 f (ceramic) cl = 10 f (ceramic) 14. the ic may enter unstable operation if the combination of ambient temperature, setting voltage, oscillation frequency, and inductors value are not adequate. if ic operates close to the maximum duty cycle, it may become unstable , even if inductor values listed below are used . v out = 3.3 v, f osc = 1.2 mhz, v in = 4.0 v , i out = 1 5 0 ma ch 1 C v lx C 2.0 v/div ; c h 2 C v out C 20 mv/div external components: l = 1.5 h (np 3 01 5 ) cin = 4.7 f (ceramic) cl = 10 f (ceramic) 15. the ic may become unstable, when it goes into continuous operation mode, and difference between v in and v out is high. v out = 1.8 v, f osc = 1.2 mhz, v in = 6 .0 v, i out = 1 0 0 ma ch 1 C v out C 1 0 mv/div ch 2 C v lx C 5 .0 v/div; external components: l = 4.7 h (np4018) cin = 4.7 f (ceramic) cl = 10 f (ceramic) 16. note on mounting (wlp - 5 - 03) a) mount ing pad design should be optimized for user's conditions. b) d o not use eutectic s solder pa s te. sn - ag - cu solder is used for the package terminals. if eutectic solder is used, mounting reliability decrease s . c) when under fill agent is used to increase interfacial bonding strength, please take enough evaluation for selection. some under fill materials and appli cation conditions may decrease bonding reliability. d) the ic has exposed surface of silicon material in the top marking face and sides , so it is weak against mechanical damages and external short circuit conditions . please , take care of handling to avoid cracks and breaks and keep the circuit open to avoid short - circuit from the out side . e) semi - transparent resin is coated on the circuit face of the package. please be noted that the usage under strong lights may affects device s performan ce. f osc , mhz v out , v l, h 3.0 0.8 v 2.5 v 4.7 C 6.8 if a n inductor less than 4.7h is used at f osc = 1.2 mhz, or inductor less than 1.5 h is used at f osc = 3.0 mhz, inductor peak current may ea s y reach the current limit threshold i lim . in this case, the ic may be not able to provide 600ma output current.
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 16 test circuits circuit ? a/b/c/e/g series d/f series external components external components l = 1.5 h (nr3015) at 3.0 mhz l = 1.5 h (nr3015) at 3.0 mhz l = 4.7 h (nr4018) at 1.2mhz l = 4.7 h (nr4018) at 1.2mhz c in = 4.7 f (ceramic) , c l = 10 f (ceramic) c in = 4.7 f (ceramic) , c l = 10 f (ceramic) r fb1 = 150 k, r fb2 = 300 k, c fb = 120 pf circuit ? circuit ? r pul l = 2 00 ? circuit ? circuit ? i out = 100 ma, on resistance = (v in C v out /0.1, circuit ? circuit ? b r pull = 1 circuit ? circuit ?
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 17 typical performance characteristics (1) efficiency vs. output current topr = 25 0 c ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237a18d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f (2) output voltage vs. output current ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237a18d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f (3) ripple voltage vs. output current ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237a18d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 18 typical performance characteristics (continued) ( 4 ) oscillation frequency vs. ambient temperature ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237a18d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f ( 5 ) supply current vs. ambient temperature ixd32 37a18c ixd3 237a18d ( 6 ) output voltage vs. ambient temperature ( 7 ) uvlo voltage vs. ambient temperature ixd3 237a18d ixd3 237a18d
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 19 typical performance characteristics (continued) ( 8 ) ce h voltage vs. ambient temparature ( 9 ) ce l voltage vs. ambient temperature ixd3 237a18d ixd3 237a18d (10 ) soft start time vs. ambient temperature ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237a18d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f (1 1 ) on resistance vs . ambient temperatur e ixd3 237a18d
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 20 (1 2 ) IXD3235/36/37 b version start wave form ixd32 37 b 1 2 c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f 100 s/div ixd3 237 b33 d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f 100 s/div (13) IXD3235/36/37 b version soft start time vs. ambient temperature ixd32 37 b 1 2 c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f ixd3 237 b33 d l = 1.5 h (nr3015), c in = 4.7 f, c l = 10 f (14) IXD3235/36/37 b version c l discharge time vs. ambient temperature ixd3 237 b33 d
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 21 typical performance characteristics (continued) (1 5 ) load transient response ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f , v in = v ce = 3.6 v, (pwm/pfm auto switching mode) i out = 1 ma ? 100 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 1 ma ? 300 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 100 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div i out = 300 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div ixd32 37a18c l = 4.7 h (nr4018) , c in = 4.7 f, c l = 10 f , v in = 3.6 v, v ce = 1.8 v (pwm mode) i out = 1 ma ? 100 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 1 ma ? 300 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 100 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div i out = 300 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 22 typical performance characteristics (continued) (1 5 ) load transient response (continued) ixd32 37a18 d l = 1.5 h (nr 3015 ) , c in = 4.7 f, c l = 10 f , v in = v ce = 3.6 v, (pwm/pfm auto switching mode) i out = 1 ma ? 100 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 1 ma ? 300 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 100 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div i out = 300 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div ixd32 37a18 d l = 1.5 h (nr 3015 ) , c in = 4.7 f, c l = 10 f , v in = 3.6 v, v ce = 1.8 v (pwm mode) i out = 1 ma ? 100 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 1 ma ? 300 ma ch1 C i out , ch2 C v out 50 mv/div, time C 50 s/div i out = 100 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div i out = 300 ma ? 1 ma ch1 C i out , ch2 C v out 50 mv/div, time C 20 0 s/div
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 23 ordering information IXD3235 ? ? ? ? ? ? - ? ixd323 6 ? ? ? ? ? ? - ? ixd323 7 ? ? ? ? ? ? - ? designator description symbol description ? type of dc/dc controller a refer to product classification b c e g d f ? ? fixed output voltage , v 08 - 40 ? - integer part, ? - decimal part, i.e. v out = 2.8 v - ? = 2, ? = 8 v out = 2.85 v - ? = 2, ? = l 0.05 v increments: 0.05 = a, 0.15 = b, 0.25 = c. 0.35 = d, 0.45 = e, 0.55 = f, 0.65 = h, 0.75 = k, 0.85 = l, 0.95 = m reference voltage 08 reference voltage (fixed) 0.8 v - ? = 0 , ? = 8 ? oscillation frequency c 1.2 mhz d 3.0 mhz ? ? - ? * packages (order limit) mr sot - 25 (3000/reel) mr - g sot - 25 (3000/reel) er usp - 6c (3000/reel) er - g usp - 6c (3000/reel) 4r - g usp - 6el (3000/reel) 0r - g wlp - 5 - 03 (3000/reel) note: 1) t he - g suffix denotes halogen and antimony free , as well as being fully r o hs compliant . 2) sot - 25, usp - 6el package are available for the a/b/c series only. 3) wlp - 5 - 03 package is available for the a/b series only. product classificati on type vout vin c l auto discharge soft start fixed adjustable 1.8 v 2 v high speed low speed a yes no no yes no no yes b yes no no yes yes yes no c yes no no yes yes no yes d no yes yes no yes no yes e yes no yes no yes no yes f no yes yes no yes yes no g yes no yes no yes yes no
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 24 package drawing and dimensions (units: mm) sot - 25 usp - 6c usp - 6c reference pattern layout usp - 6c reference metal mask design
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 25 package drawing and dimensions (continued) (units: mm) usp - 6el wlp - 5 - 03 note: a part of the pin may appear from the side of the package because of its structure, but reliability of the package and strength will be not below the standard. usp - 6el reference pattern layout usp - 6 el reference metal mask design
product specification ixd 3235/36/37 ps03 42 01 - 0515 preliminary 26 marking sot - 25 ? represents product series product series mark IXD3235 ixd3236 ixd3237 a 4 5 6 b c d e c k l m d k l m e 4 5 6 f 2 7 b g c d e usp - 6c/usp - 6el ? represents integer number of the output voltage and oscillation frequency a/b/c/f series v out , v mark f osc = 1.2 mhz f osc = 3.0 mhz 0.x a f 1.x b h 2.x c k 3.x d l 4.x e m wlp - 5 - 03 e/g/d series v out , v mark f osc = 1.2 mhz f osc = 3.0 mhz 0.x a f 1.x b h 2.x c k 3.x d l 4.x e m ? r epresents decimal value of the output voltage v out , v mark v out , v mark x.00 0 x.05 a x.10 1 x.15 b x.20 2 x.25 c x.30 3 x.35 d x.40 4 x.45 e x.50 5 x.55 f x/60 6 x.65 h x.70 7 x.75 k x.80 8 x.85 l x.90 9 x,95 m ? ? represents production lot number 01 09 0a 0z 11 9z a1 a9 aa az b1 zz in order (g, i, j, o, q , and w excluded)
product specification IXD3235/36/37 ps03 42 01 - 0515 preliminary 27 customer support to share comments, get your technical questions answered, or report issues you may be experiencing with our products, please visit zilogs technical support page at http://support.zilog.com . to learn more about this product, find additional documentation, or to discover other fac - ets about zilog product offerings, please visit the zilog knowledge base at http:// zilog.com/kb or consider participating in the zilog forum at http://zilog.com/forum . this publication is subject to replacement by a later edition . to determine whether a later edition exists, please visit the zilog website at http://www.zilog.com . warning: do not use this product in life support systems. life support policy zilogs products are not authorized for use as critical components in life support devices or systems without the express prior written approval of the president and general counsel of zilog corporation. as used herein life support devices or systems are devices which (a) are intended for su rgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. a critic al component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. document disclaimer ?2015 zilog, inc. a ll rights reserved. information in this publication concerning the devices, applications, or technology described is intended to suggest possible uses and may be superseded. zilog, inc. does not assume liability for or provide a representation of accuracy of the information, devices, or technology described in this document. zilog also does not assume liability for intellectual property infringement related in any manner to use of information, devices, or technology described herein or otherwise. the inform ation contained within this document has been verified according to the general principles of electrical and mechanical engineering.

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