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www.belling.com.cn 1 high efficiency low noise pfm step-up dc/dc conv erter bl853 4 description BL8534 series are cmos-based pfm step- up dc-dc converter. the converter can start up by supply voltage as low as 0.8v, and capable of delivering maximum 200ma output current at 3.3v output with 1.8v input voltage. quiescent current drawn from power source is as low as 20ua. all of these features make BL8534 series be suitable for the portable devices, which are supplied by a single battery to four-cell batteries. to reduce the noise caused by the switch regulator, BL8534 is well considerated in circuit design and manufacture. so that the interferer to other circuits by the device is reduced greatly. BL8534 integrates stable reference circuits and trimming technology, so it can afford high precision and low temperature-drift coefficient of the output voltage. BL8534 is available in sot-89-3, sot-23-3, sot-23-5 and to-92 packages that are pb free. and in 5-pin packages, such as sot-23- 5, the device can be switch on or off easily by ce pin, to minimize the standby supply current. features deliver 200ma at 3.3v output voltage with 1.8v input voltage low start-up voltage (when the output current is 1ma)-----------------------------0.8v output voltage can be adjusted from 2.5v to 6.0v (in 0.1v step) output voltage accuracy --------------- 2 low temperature-drift coefficient of the output voltage-------------------- 100ppm/ only three external components are necessary: an inductor, a schottky diode and an output filter capacitor low quiescent current drawn from power source-------------------------------------<20ua applications power source for pda, dsc, mp3 player, electronic toy and wireless mouse power source for a single or dual-cell battery-powered equipments power source for led typical application electrical characteristics lc3000cc3tr33 0 1 2 3 4 0 200 400 600 800 output current(ma) output voltage(v) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v BL8534 BL8534
www.belling.com.cn 2 BL8534 ordering information BL8534 1 2 3 4 code description 1 temperature & rohs: c: -40~85 c, pb free rohs std. 2 package type: b3: sot-23-3 b5: sot-23-5 c3: sot-89-3 h: to-92 3 packing type: tr: tape & reel (standard) bg: bag (to-92) 4 output voltage e.g. 25=2.5v 33=3.3v 60=6.0v marking description product classification BL8534cb3tr product classification BL8534cb5tr marking marking ldxzz ld: product code ldxzz ld: product code x: output voltage x: output voltage zz: date code zz: date code product classification BL8534cc3tr product classification BL8534chbg marking marking ldxx ld: product code ldxx ld: product code yybzz xx: output voltage yybzz xx: output voltage yy: lot no. yy: lot no. b: fab code b: fab code zz: date code zz: date code ld: product code; x: output voltage for sot-23-3 and sot-23-5; xx: output voltage for sot-89-3 and to-92. 25 stand s for 2.5v, 60 stands for 6.0v; z: the year of manufacturing, 7 stands for year 2 007, 8 stands for year 2008; z: the week of manufacturing. a stands for week 1 , z stands for week 26, a stands for week 27, z stands for week 52. output voltage code for sot-23-3 and sot-23-5 vout code vout code vout code vout code 2.5v 5 3.0v 0 3.8v 8 4.5v 5 2.7v 7 3.3v 3 4.0v 0 5.0v 0 2.8v 8 3.6v 6 4.2v 2 6.0v 0
www.belling.com.cn 3 BL8534 absolute maximum rating parameter value max input voltage -0.3v-10v ce pin voltage -0.3v-(vout+0.3) lx pin output current 0.7a lx pin voltage 10v operating junction temperature (t j ) 125 c ambient temperature (t a ) -40 c -85 c power dissipation sot-23-3 250mw sot-23-5 250mw sot-89-3 500mw to-92 500mw storage temperature (ts) -40 c -150 c lead temperature & time 260 c, 10sec note: exceed these limits to damage to the device. exposure to absolute maximum rating conditions may affect device reliability. recommended work conditions item min recommended max. unit input voltage range 0.8 vout v inductor 10 100 h input capacitor 0 10 f output capacitor 47 f ambient temperature -40 85 c block diagram note: ce pin is only available on 5 pins packages. BL8534
www.belling.com.cn 4 BL8534 pin description ce chip enable (active high) vss ground out output, power supply for internal lx switching pin nc not connected electrical characteristics symbol item test conditions reference data unit min typ max vout_rt rated output voltage 2.45 2.5 2.55 v 2.646 2.7 2.754 2.94 3.0 3.06 3.234 3.3 3.366 3.528 3.6 3.672 3.92 4.0 4.08 4.9 5.0 5.1 5.88 6.0 6.12 iin input current iout=0ma vout=vout*0.6 15 20 ua vstart start-up voltage iout=1ma vs 0 ? 2v 0.8 0.9 v vhold hold-on voltage iout=1ma vs 2 ? 0v 0.6 0.7 v i dd quiescent current drawn from power source without external components, vout =vout_rt1.05 4 7 ua rswon switch on resistance 0.8 i lxleak lx leakage current vout=vlx=6v (v ce =0v in 5 pins packages) 0.5 5 ua v ceh ce h threshold voltage v ce 0 ? 2v 0.8 v v cel ce l threshold voltage v ce 2 ? 0v 0.3 v fosc_max oscillator frequency lx on l side vout=vout_rt*0.96 150 khz t off_min minimum off time 1.4 us maxdty oscillator duty cycle lx on l side 70 75 80
www.belling.com.cn 5 BL8534 detailed description the BL8534 series are boost structure, voltage-type pulse-frequency modulation (pfm) step-up dc-dc converter. only three external components are necessary: an inductor, an output filter capacitor and a schottky diode. and the converters low noise and low ripple output voltage can be adjusted from 2.5v to 5.0v, 0.1v step. by using the depletion techniques, the quiescent current drawn from power source is lower than 7ua. the high efficiency device consists of resistors for output voltage detection and trimming, a start-up voltage circuit, an oscillator, a reference circuit, a pfm control circuit, a switch protection circuit and a driver transistor. the pfm control circuit is the core of the BL8534. this block controls power switch on duty cycle to stabilize output voltage by calculating results of other blocks which sense input voltage, output voltage, output current and load conditions. in pfm modulation system, the frequency and pulse width is fixed. the duty cycle is adjusted by skipping pulses, so that switch on-time is changed based on the conditions such as input voltage, output current and load. the oscillate block inside BL8534 provides fixed frequency and pulse width wave. the reference circuit provides stable reference voltage to output stable output voltage. because internal trimming technology is used, the chip output change less than 2%. at the same time the problem of temperature-drift coefficient of output voltage is considered in design, so temperature-drift coefficient of output voltage is less than 100ppm/ high-gain differential error amplifiers guarantees stable output voltage at difference input voltage and load. in order to reduce ripple and noise, the error amplifier is designed with high band-with. though at very low load condition, the quiescent current of chip do affect efficiency certainly. the four main energy loss of boost structure dc-dc converter in full load are the esr of inductor, the voltage of schottky diode, on resistor of internal n-channel mosfet and its driver. in order to improve the efficiency, BL8534 integrates low on- resistor n-channel mosfet and well design driver circuits. the switch energy loss is limited at very low level. components selection thus it can be seen, the inductor and schottky diode affect the conversion efficiency greatly. the inductor and the capacitor also have great influence on the output ripple voltage of the converter. so it is necessary to choose a suitable inductor, a capacitor and a right schottky diode, to obtain high efficiency, low ripple and low noise. before discussion we define out in out v v v d - o inductor selection above all, we should define the minimum value of the inductor that can ensure the boost dc-dc to operate in the continuous current-mode condition. f r d) d( l l min 2 1 2 - 3 the above expression is got under conditions of continuous current mode, neglect schottky diodes voltage, esr of both inductor and capacitor. the actual value is greater that it. if inductors value is less than l min the efficiency of dc-dc converter will drop greatly, and the dc-dc circuit will not be stable. secondly, consider the ripple of the output voltage,
www.belling.com.cn 6 BL8534 lf dv i in = d lf dv r d v i in l in max 2 ) 1( 2 + - = if inductor value is too small, the current ripple through it will be great. then the current through diode and power switch will be great. because the power switch on chip is not ideal switch, the energy of switch will improve. the efficiency will fall. thirdly in general, smaller inductor values supply more output current while larger values start up with lower input voltage and acquire high efficiency. an inductor value of 3uh to 1mh works well in most applications. if dc-dc converter delivers large output current (for example: output current is great than 50ma), large inductor value is recommended in order to improve efficiency. if dc-dc must output very large current at low input supply voltage, small inductor value is recommended. the esr of inductor will affect efficiency greatly. suppose esr value of inductor is r l r load is load resistor then the energy can be calculated by following expression 2 ) 1( d r r load l - ? d h for example: input 1.5v, output is 3.0v, r load =20 , r l =0.5 , the energy loss is 10%. consider all above inductor value of 47uh esr<0.5 is recommended in most applications. large value is recommended in high efficiency applications and smaller value is recommended capacitor selection ignore esr of capacitor the ripple of output voltage is: cf r d v v r load out out = d = so large value capacitor is needed to reduce ripple. but too large capacitor value will slow down system reaction and cost will improve. so 100uf capacitor is recommended. larger capacitor value will be used in large output current system. if output current is small (<10ma), small value is needed. consider esr of capacitor ripple will increase out esr max v r i r r + = ' when current is large, ripple caused by esr will be main factor. it may be greater than 100mv the esr will affect efficiency and increase energy loss. so low-esr capacitor (for example: tantalum capacitor) is recommend or connects two or more filter capacitors in parallel. diode selection rectifier diode will affects efficiency greatly though a common diode (such as 1n4148) will work well for light load it will reduce about 5%~10% efficiency for heavy load for optimum performance, a schottky diode (such as 1n5817 1n5819 1n5822) is recommended.
www.belling.com.cn 7 BL8534 test circuits figure 1: output voltage test circuit (i out =1ma) figure 2: start-up voltage test circuit (i out =1ma) figure 3: hold-on voltage test circuit (i out =1ma) figure 4: quiescent current test circuit (vs=vout_r t*1.05 r=1k c=0.1uf) figure 5: oscillator frequency and duty cycle test circuit (vs=vout_rt*0.95 r=1k ) BL8534 BL8534 BL8534 BL8534 BL8534
www.belling.com.cn 8 BL8534 typical performance characteristics recommended operating conditions: cin=47uf, cout=10 0uf, t opt =25 c. (unless otherwise noted) and all the tests below are made on BL8534cc3tr33. quiescent current vs input voltage 0 10 20 30 40 50 1 1.5 2 2.5 3 input voltage(v) quiescent current(ua) quiescent current vs input voltage 0 10 20 30 40 50 1 1.5 2 2.5 3 input voltage(v) quiescent current(ua) output voltage vs output current 0 1 2 3 4 0 200 400 600 800 output current(ma) output voltage(v) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v output voltage vs output current 0 1 2 3 4 0 200 400 600 800 output current(ma) output voltage(v) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v efficiency vs load current 0% 20% 40% 60% 80% 100% 1 10 100 1000 load current(ma) efficiency(%) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v efficiency vs load current 0% 20% 40% 60% 80% 100% 1 10 100 1000 load current(ma) efficiency(%) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v l=10uh l=10uh l=10uh l=47uh l=47uh l=47uh
www.belling.com.cn 9 BL8534 typical performance characteristics (continued) recommended operating conditions: cin=47uf, cout=10 0uf, t opt =25 c. (unless otherwise noted) and all the tests below are made on BL8534cc3tr33. output ripple vs load current 0 20 40 60 80 100 0 200 400 600 800 load current(ma) output ripple(mv) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v output ripple vs load current 0 50 100 150 200 250 0 100 200 300 400 500 600 700 load current(ma) output ripple(mv) vin=1.2v vin=1.2v vin=1.2v vin=1.2v vin=1.5v vin=1.5v vin=1.5v vin=1.5v vin=2v vin=2v vin=2v vin=2v vin=2.5v vin=2.5v vin=2.5v vin=2.5v vin=3v vin=3v vin=3v vin=3v minimum start up voltage vs output current 0.0 0.2 0.4 0.6 0.8 1.0 0 5 10 15 20 output current(ma) input voltage(v) l=47uh l=10uh l=10uh l=47uh
www.belling.com.cn 10 BL8534 package line package sot-23-3 devices per reel 3000pcs unit mm package dimension package sot-23-5 devices per reel 3000pcs unit mm package specification
www.belling.com.cn 11 BL8534 package line (continued) package sot-89-3 devices per reel 1000pcs unit mm package dimension: package to-92 devices per bag 1000pcs unit mm package dimension:

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