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1/35 xc9511 series synchronous step-down dc/dc converter with built-in ldo regulator in parallel plus voltage detector general description the xc9511 series consists of a step-down dc/dc converter and a high-speed ldo regulator connected in parallel with the dc/dc converter's output. a voltage detector is also built-in. since the input for the ldo voltage regulator block comes from the input power supply, it is suited for use with various applications. the dc/dc converter block incorporates a p-channel driver transistor and a synchronous n-channel switching transistor. with an external coil, diode and two capacitors, the xc9511 can deliver output currents up to 800ma at efficiencies over 90%. the xc9511 is designed for use with small ceramic capacitors. a choice of three switching frequencies are available, 300 khz, 600 khz, and 1.2 mhz. output voltage settings for the dc/dc and vr are set-up internally in 100mv steps within the range of 0.9v to 4.0v ( 2.0%). for the vd, the range is of 0.9v to 5.0v ( 2.0%). the soft start time of the series is internally set to 5ms. with the built-in u.v.l.o. (under voltage lock out) function, the internal p-channel driver transistor is forced off when input voltage becomes 1.4 v or lower. applications cd-r / rw, dvd hdd pdas, portable communication modem palmtop computers cellular phones cameras, video recorders typical application circuit features dc/dc converter with built-in ldo and vd function input voltage range : 2.4v ~ 6.0v low esr capacitor : ceramic capacitor compatible vd function : three vd sensing options for either v dd , d cout , or v rout package : sop-8 2/35 xc9511 series designator description symbol description control methods and the vd sense pin as chart below : - setting voltage & specifications internal standard : setting voltage and specifications of each dc/dc, vr, and vd (based on the internal standard) 3 : 300khz 6 : 600khz dc/dc oscillation frequency c : 1.2mhz package s : sop-8 r : embossed tape, standard feed device orientation l : embossed tape, reverse feed pin number pin name function 1 p gnd power ground 2 p vdd power supply 1 3 a vdd power supply 2 4 v dout vd output 5 a gnd analog ground 6 v rout vr output 7 d cout dc/dc output 8 lx switch series dc/dc control methods vd sense a v dd b d cout c pwm control v rout d v dd e d cout xc9511 f pfm/pwm automatic switch v rout pin configuration pin assignment product classification ordering information xc9511 ????? the input for the voltage regulator block comes from v dd sop-8 ( top view ) control methods and vd sense pin pgnd 1 pvdd 2 a vdd 3 vdout 4 8 lx 7 dcout 6 vrout 5 agnd 3/35 x c9511 series parameter symbol ratings unit a vdd pin voltage a vdd - 0.3 ~ 6.5 v p vdd pin voltage p vdd a vdd - 0.3 ~ a vdd + 0.3 v d cout pin voltage d cout - 0.3 ~ a vdd + 0.3 v v rout pin voltage v rout - 0.3 ~ a vdd + 0.3 v v rout pin current i rout 800 ma v dout pin voltage v dout - 0.3 ~ v dd + 0.3 v v dout pin current i vd 50 ma lx pin voltage lx - 0.3 ~ v dd + 0.3 v lx pin current i lx 1300 ma power dissipation sop-8 pd 650 mw operating temperature range topr - 40 ~ + 85 storage temperature range tstg - 55 ~ + 125 block diagram absolute maximum ratings * diodes shown in the above circuit are p rotective diodes ta = 2 5 (*) when implemented on a glass epoxy pcb. 4/35 xc9511 series parameter symbol conditions min. typ. max. units circuit supply current 1 i dd 1 v in =ce=d cout =5.0v - 250 310 a 1 supply current 2 i dd 2 v in =ce=5.0v, d cout =0v - 300 360 a 1 input voltage range v in 2.4 - 6.0 v - parameter symbol conditions min. typ. max. units circuit output voltage dc out (e) connected to the external components i dout =30ma 1.470 1.500 1.530 v 3 oscillation frequency f osc connected to the external components i dout =10ma 1.02 1.20 1.38 mhz 3 maximum duty ratio maxduty d cout =0v 100 - - % 4 minimum duty ratio minduty d cout =v in - - 0 % 4 pfm duty ratio * xc9511d/e/f pfmduty connected to the external components no load 21 30 38 % 3 u.v.l.o. voltage (*1) vuvlo connected to the external components 1.00 1.40 1.78 v 3 lx sw ?high? on resistance (*2) rlxh d cout =0v, lx=v in -0.05v - 0.5 0.9 5 lx sw ?low? on resistance rlxl connected to the external components, v in =5.0v - 0.5 0.9 3 lx sw ?high? leak current (*11) ileakh v in =lx=6.0v, ce=0v - 0.05 1.00 a 11 lx sw ?low? leak current (*11) ileakl v in =6.0v, lx=ce=0v - 0.05 1.00 a 11 maximum output current imax1 connected to the external components 800 - - ma 3 current limit (*8) ilim1 1.0 1.1 - a 6 efficiency (*3) effi connected to the external components i dout =100ma - 90 - % 3 output voltage i dout =30ma temperature characteristics u dc out topr ? dc out -40 Q topr Q 85 - 100 - ppm/ 3 soft-start time tss connected to the external components, ce=0v t v in , i dout =1ma 2 5 10 ms 3 latch time (*4, 9) tlat connected to the external components, v in =ce=5.0v, short d cout by 1 resistor - 8 25 ms 10 electrical characteristics xc9511xxxcsx common characteristics topr=25 dc/dc converter (1.5v product) topr=25 5/35 x c9511 series parameter symbol conditions min. typ. max. units circuit output voltage vr out (e) ir out =30ma 3.234 3.300 3.366 v 2 maximum output current imax2 400 - - ma 2 load regulation u vr out 1ma Q ir out Q 100ma - 15 50 mv 2 dropout voltage 1 (*5) vdif 1 ir out =100ma - 50 110 mv 2 dropout voltage 2 vdif 2 ir out =200ma - 100 200 mv 2 ir out =30ma line regulation u vrout u v in ? vr out vr out (t)+1v Q v in Q 6v - 0.05 0.25 %/v 2 current limit ilim2 vr out =vr out (e) x 0.9 480 600 - ma 7 short-circuit current ishort vr out =vss - 30 - ma 7 ripple rejection rate psrr v in ={v out (t)+1.0} v dc +0.5vp-pac, ir out =30ma, f=1khz - 60 - db 12 output voltage ir out =30ma temperature characteristics u vr out u topr ? vr out -40 Q topr Q 85 - 100 - ppm/ 2 parameter symbol conditions min. typ. max. units circuit detect voltage v df (e) ce=0v 2.646 2.700 2.754 v 8 hysteresis range v hys v hys =[v dr (e) (*10) - v df (e)] / v df (e) x 100 2 5 8 % 8 vd output current ivd vdout=0.5v, ce=0v 1 - - ma 9 output voltage temperature characteristics u v df u topr ? vdf -40 Q topr Q 85 - 100 - ppm/ 8 electrical characteristics (continued) regulator (3.3v product) topr=25 detector (2.7v product) topr=25 test conditions: unless otherwise stated: dc/dc : vin=3.6v [dc out :1.5v] vr: v in = 4.3v (v in =vr out (t) + 1.0v) vd: v in =5.0v common conditions for all test items: ce=v in , mode=0v * vr out (t) : setting output voltage note: *1: including hysteresis operating voltage range. *2: on resistance ( )= 0.05 (v) / ilx (a). *3: effi = { ( output voltage x output current ) / ( input voltage x input current) } x 100 *4: time until it short-circuits dc out with gnd through 1 of resistance from a state of operation and is set to dc out =0v from current limit pulse generating. *5: vdif = (v in 1 (*6) - vr out 1 (*7) ) *6: v in 1 = the input voltage when vrout1 appears as input voltage is gradually decreased. *7: vr out 1 = a voltage equal to 98% of the output voltage whenever an amply stabilized i out {vr out (t) + 1.0v} is input. *8: current limit = when v in is low, limit current may not be reached because of voltage falls caused by on resistance or serial resistance of coils. *9: integral latch circuit=latch time may become longer and latch operation may not work when v in is 3.0v or more. *10: v dr(e) = vd release voltage *11: when temperature is high, a current of approximately 5.0 a (maximum) may leak. *12: when using the ic with a regulator output at almost no load, a capacitor should be placed as close as possible between avdd and agnd (c in 2), connected with low impedance. please also see the recommended pattern layout on page 13 for your reference. should it not be possible to place the input capacitor nearby, the regulated output level may increase up to the v dd level while the load of the dc/dc converter increases and the regulator output is at almost no load. xc9511xxxcsx (continued) 6/35 xc9511 series circuit 1 supply current circuit 2 output voltage (vr), load regulation, dropout voltage, maximum output current circuit 3 output voltage (dc/dc) oscillation frequency, u.v.l.o. voltage, soft start time circuit 4 minimum duty cycle, maximum duty cycle maximum output current, efficiency, (pfm duty cycle), circuit 5 lx on resistance circuit 6 current limit 1 (dc/dc) test circuits 7/35 x c9511 series circuit 7 current limit 2 (vr), short current (vr) circuit 8 detect voltage, release voltage (hysteresis range) * for the measurement of the vdd_sense products, the input voltage was controlled. circuit 9 vd output current circuit 10 latch time * for the measurement of the vdd_sense products, the input voltage was controlled. circuit 11 off-leak circuit 12 ripple rejection rate test circuits ( continued ) 8/35 xc9511 series fosc l 1.2mhz 4.7 h (cdrh4d28c, sumida) 600khz 10 h (cdrh5d28, sumida) 300khz 22 h (cdrh6d28, sumida) c in c l1 c l2 * 2 i rout 300ma 4.7 f (ceramic, taiyo yuden) 4.7 f (ceramic, taiyo yuden) 10 f (ceramic, taiyo yuden) i rout R 300ma 10 f (ceramic, taiyo yuden) typical application circuit sop-8 ( top view ) operational explanation the xc9511 series consists of a synchronous step-down dc/dc converter, a high speed ldo voltage regulator, and a voltage detector. dc/dc converter the series consists of a reference voltage source, ramp wave circuit, error amplifier, pwm comparator, phase compensation circuit, output voltage adjustment resistors, driv er transistor, synchronous switch, current limiter circuit, u.v.l.o. circuit and others. the series ics compare, using the error amplifier, the voltage of the internal voltage reference source with the feedback voltage from the v out pin through split resistors. phase compensation is performed on the resulting error amplifier output, to input a si gnal to the pwm comparator to determine the turn-on time during pwm operation. the pwm comparator compares, in terms of voltage level, the signal from the error amplifier with the ramp wave from the ramp wave circuit, and delivers the resulting output to the buffer driver circuit to cause the lx pin to output a switching duty cycle. this process is continuously performed to ensure stable output voltage. the current feedback circuit monitors the p-channel mos driver transistor current for each switching operation, and modulates the error amplifier output signal to provide multiple feedback signals. this enables a stable feedback loop even when a low esr capacitor, such as a ceramic capacitor, is used, ensuring stable output voltage. 9/35 x c9511 series operational explanation ( continued ) 10/35 xc9511 series . 11/35 x c9511 series application information 1. the xc9511 series is designed for use with a ceramic output capacitor. if, however, the potential difference between dropout voltage or output current is too large, a ceramic capacitor may fail to absorb the resulting high switching energy and oscillation could occur on the output. if the input-output potential difference is large, connect an electrolytic capacitor in parallel to compensate for insufficient capacitance. 2. spike noise and ripple voltage arise in a switching regulator as with a dc/dc converter. these are greatly influenced by external component selection, such as the coil inductance, capacitance values, and board layout of external components. once the design has been completed, verification with actual components should be done. 3. when the difference between v in and v out is large in pwm control, very narrow pulses will be outputted, and there is the possibility that some cycles may be skipped completely. 4. when the difference between v in and v out is small, and the load current is heavy, very wide pulses will be outputted and there is the possibility that some cycles may be skipped completely: in this case, the lx pin may not go low at all. notes on use dc/dc waveform (3.3v, 1.2mhz) 5. the ic's dc/dc converter operates in synchronous mode when the coil current is in a continuous state and non-synchronous mode when the coil current is in a discontinuous state. in order to maintain the load current value when synchronous switches to non-synchronous and vise versa, a ripple voltage may increase because of the repetition of switching between synchronous and non-synchronous. w hen this state continues, the increase in the ripple voltage stops. to reduce the ripple voltage, please increase the load capacitance value or use a schottky diode externally. when the current used becomes close to the value of the load current when synchronous switches to non- synchronous and vise ve rsa, the switching current value can be changed by changing the coil inductance value. in case changes to coil inductance are to values other than the recommended coil inductance values, verification with actual components should be done. ics = (v in - d cout ) x onduty / (l x fosc) ics: switching current from synchronous re ctification to non-synchronous rectification onduty: onduty ratio of p-ch driver transistor ( . =.step down ratio : d cout / v in ) l: coil inductance value fosc: oscillation frequency i dout : the dc/dc load current < external components> l:4.7 h(cdrh4d28c,sumida) cin:4.7 f(ceramic) cl:10 f(ceramic) < external components> l:4.7 h(cdrh4d28c,sumida) cin:4.7 f(ceramic) cl:10 f(ceramic) 12/35 xc9511 series application information (continued) 6. when the xc9511d to f series operate in pwm/pfm automatic switching control mode, the reverse current may become quite high around the load current value when synchronous switches to non-synchronous and vise versa (also refer to no. 5). under this condition, switch ing synchronous rectification and non-synchronous rectification may be repeated because of the reverse current, and the ripple voltage may be increased to 100mv or more. the reverse current is the current that flows in the p gnd direction through the n-ch driver transistor from the coil. the conditions which cause this operation are as follows. pfm duty < step down ratio = dc out / v in x 100 (%) pfm duty: 30% (typ.) please use xc9511a to c types (pwm control) in cases where the load current value of the dc/dc converter is close to synchronous. notes on use ( continued ) dc/dc waveform (1.8v, 600khz) @ vin=6.0v 7. with the dc/dc converter of the ic, the peak current of t he coil is controlled by the current limit circuit. since the peak current increases when dropout voltage or load current is high, current limit starts operating, and this can lead to instability. when peak current becomes high, please adjust the coil inductance value and fully check the circuit operation. in addition, please calculate the peak current according to the following formula: peak current : ipk = (v in - d cout ) x onduty / (2 x l x fosc) + i dout 8. when the peak current, which exceeds limit current flows within the specified time, the built-in driver transistor is turned off (the integral latch circuit). during the time un til it detects limit current and before the built-in transistor can be turned off, the current for limit current flows; therefore, care must be taken when selecting the rating for the coil or the schottky diode. 9. when v in is low, limit current may not be reached because of voltage falls caused by on resistance or serial resistance of the coil. 10. in the integral latch circuit, latch time may become longer and latch operation may not work when v in is 3.0v or more. 11. use of the ic at voltages below the recommended voltage range may lead to instability. 12. this ic and the external components should be used within the stated absolute maximum ratings in order to prevent damage to the device. 13. when using ic with a regulator output at almost no load, a capacitor should be placed as close as possible between a vdd and a gnd (c in 2), connected with low impedance. please also see the recommended pattern layout for your reference. should it not be possible to place the input c apacitor nearby, the regulated output level may increase up to the v dd level while the load of the dc/dc converter increases and the regulator output is at almost no load. < external components> l:10 h(cdrh5d28,sumida) cin:4.7 f(ceramic) cl:10 f(ceramic) step-down ratio: 1.8v / 6.0v = 30% 13/35 x c9511 series application information (continued) 14. should the bi-directional load current of the synchronous dc/dc converter and the regulator become large, please be careful of the power dissipation when in use. please calculate power dissipation by using the following formula. pd=pddc/dc + pdvr dc/dc power dissipation (when in synchronous operation): pddc/dc = i dout 2 x ron vr power dissipation: pdvr=(v in ? vr out ) x ir out ron: on resistance of the built-in driver transistor to the dc/dc (= 0.5 14/35 xc9511 series typical performance characteristics (a) dc/dc converter (1) efficiency vs. output current 15/35 x c9511 series typical performance characteristics (continued) (2) output voltage vs. output current (a) dc/dc converter (continued) 16/35 xc9511 series typical performance characteristics (continued) (3) output voltage vs. ripple voltage (a) dc/dc converter (continued) 17/35 x c9511 series typical performance characteristics (continued) (4) output voltage vs. ambient temperature (5) soft-start time vs. ambient temperature (a) dc/dc converter (continued) 18/35 xc9511 series typical performance characteristics (continued) ambient temperature :ta( ) ambient temperature :ta( ) (6) lx pch/nch on resistance vs. input voltage (7) oscillation frequency vs. ambient temperature (8) u.v.l.o. voltage vs. ambient temperature (a) dc/dc converter (continued) 19/35 x c9511 series typical performance characteristics (continued) (9-1) dc/dc load transient response (d cout : 1.5v, fosc: 1.2mhz) (a) pwm control* (*xc9511a/b/c series) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 20/35 xc9511 series (9-2) dc/dc load transient response (d cout : 1.8v, fosc: 1.2mhz) (a) pwm control* (*xc9511a/b/c series) typical performance characteristics (continued) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 21/35 x c9511 series typical performance characteristics (continued) (9-3) dc/dc load transient response (d cout : 3.3v, fosc: 600khz) (a) pwm control* (*xc9511a/b/c series) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 22/35 xc9511 series typical performance characteristics (continued) (9-4) dc/dc load transient response (d cout : 1.5v, fosc: 600khz) (a) pwm control* (*xc9511a/b/c series) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 23/35 x c9511 series typical performance characteristics (continued) (9-5) dc/dc load transient response (d cout : 1.8v, fosc: 600khz) (a) pwm control* (*xc9511a/b/c series) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 24/35 xc9511 series typical performance characteristics (continued) (9-6) dc/dc load transient response (d cout : 3.3v, fosc: 600khz) (a) pwm control* (*xc9511a/b/c series) (b) pwm/pfm automatic switching control* (*xc9511d/e/f series) (a) dc/dc converter (continued) 25/35 x c9511 series typical performance characteristics (continued) (b) voltage regulator (1) output voltage vs. input voltage 26/35 xc9511 series typical performance characteristics (continued) (2) output voltage vs. output current (current limit) (b) voltage regulator (continued) 27/35 x c9511 series typical performance characteristics (continued) ta = - 4 0 (b) voltage regulator (continued) (3) dropout voltage vs. output current 28/35 xc9511 series typical performance characteristics (continued) (4) output voltage vs. output current (b) voltage regulator (continued) 29/35 x c9511 series typical performance characteristics (continued) (5) ripple rejection ratio vs. ripple frequency (b) voltage regulator (continued) 30/35 xc9511 series typical performance characteristics (continued) (6) vr load transient response (b) voltage regulator (continued) 31/35 x c9511 series typical performance characteristics (continued) (c) voltage detector (1) output current vs. input voltage (2) detect voltage vs. input voltage 32/35 xc9511 series typical performance characteristics (continued) (3) detect voltage, release voltage vs. ambient temperature (c) voltage detector (continued) 33/35 x c9511 series typical performance characteristics (continued) (d) common (1) supply current vs. ambient temperature (dc/dc & vr & vd) 34/35 xc9511 series mark oscillation frequency product series 3 300khz xc9511 xxx3ax 6 600khz xc9511 xxx6ax c 1.2mhz xc9511xxxcax mark production year 3 2003 4 2004 mark product series 1 1 xc9511xxxxsx mark dc/dc control vd sense product series a v dd xc9511axxxsx b d cout xc9511bxxxsx c pwm control v rout xc9511cxxxsx d v dd xc9511dxxxsx e d cout xc9511exxxsx f pwm, pfm/pwm manual switch v rout xc9511fxxxsx mark dc/dc vr vd product series 1 4 1.8v 3.3v 4.0v xc9511*14*s* marking rule sop-8 ? represents product series represents dc/dc control methods, mode pin and vd sense pin packaging information sop-8 ? represents detect voltage dc/dc,vr and vd (ex.) represents the production lot number 0 to 9,a to z reverse character 0 to 9, a to z repeated (g, i, j, o, q, w excepted) note: no character inversion used. represents single digit of production year (ex.) sop-8 (top view) represents oscillation frequency 35/35 x c9511 series 1. the products and product specifications contained herein are subject to change without notice to improve performance characteristics. consult us, or our representatives before use, to confirm that the information in this catalog is up to date. 2. we assume no responsibility for any infringement of patents, patent rights, or other rights arising from the use of any information and circuitry in this catalog. 3. please ensure suitable shipping controls (including fail-safe designs and aging protection) are in force for equipment employing products listed in this catalog. 4. the products in this catalog are not developed, designed, or approved for use with such equipment whose failure of malfunction can be reasonably expected to directly endanger the life of, or cause significant injury to, the user. (e.g. atomic energy; aerospace; transport; combustion and associated safety equipment thereof.) 5. please use the products listed in this catalog within the specified ranges. should you wish to use the products under conditions exceeding the specifications, please consult us or our representatives. 6. we assume no responsibility for damage or loss due to abnormal use. 7. all rights reserved. no part of this catalog may be copied or reproduced without the prior permission of torex semiconductor ltd. |
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