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ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 1 BL9310 1.5 mhz, 1a synchronous buck converter features ? high efficiency: up to 96% ? 1.5mhz constant switching frequency ? current mode operation for excellent line and load transient response ? no schottky diode required ? 2.5v to 5.5v input voltage range ? 1.0v,1.2v,1.5v,1.8v,2.5v and 3.3v fixed/adjustable output voltage ? 100% duty cycle in dropout mode ? low quiescent current: 200a ? over temperature protection ? short circuit protection ? shutdown quiescent current < 1a ? space saving 5-pin thin sot23 package applications ? cellular and smart phones ? wireless handsets and dsl modems ? microprocessors and dsp core supplies ? pdas ? digital still and video cameras ? mp3/mp4/mp5 players ? portable instruments ? gps receivers description the BL9310 is a constant frequency, 1.5mhz, slope compensated current mode pwm step- down converter working under an input voltage range of 2.5v to 5.5v. this feature makes the BL9310 suitable for single cell li- ion battery-powered applications. the internal synchronous rectifier is desired to increase efficiency without an external schottky diode. 100% duty cycle capability extends battery life in portable devices, while the quiescent current is 200a at no load, and drops to < 1a in shutdown. pulse skipping mode operation increases efficiency at light loads, further extending battery life. the BL9310 is offered in a low profile (1mm) 5-pin, thin sot23 package, and is available in an adjustable version and fixed output versions of 1.0v, 1.2v, 1.5v , 1.8v, 2.5v and 3.3v. ordering information typical application BL9310 Cxx x xxx figure 1. BL9310-adj typical application circuit package trn: tsot23-5 rn: sot23-5 output voltage 10: 1.0v 12: 1.2v 15: 1.5v 18: 1.8v 25: 2.5v 33: 3.3v ad: adjustable features: p: standard (default, lead free) c: customized
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary information. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 2 BL9310 1.5 mhz, 1a synchronous buck converter absolute maximum rating (note 1) input supply voltage -0.3v to +6v run, v fb voltages -0.3v to +v in sw voltages -0.3v to (v in +0.3v) p-channel switch source current (dc) 1.1a n-channel switch sink current (dc) 1.1a peak sw sink and source current1.5a operating temperature range -40c to +85c junction temperature (note2) +125c storage temperature range -65c to +150c lead temperature (soldering, 10s) +300c package information adjustable output version fixed output versi ons thermal resistance (note 4) package h ja h jc tsot23-5 220 c/w 110c/w sot23-5 250 c/w 130c/w note 1: absolute maximum ratings are those values beyond wh ich the life of a device may be impaired. note 2: t j is calculated from the ambient temperature t a and power dissipation p d according to the following formula: t j = t a + (p d ) x (220c/w). note 3: i: product code y: year of manufacturing w: week o f manufacturing note 4: thermal resistance is specified with approximately 1 square of 1 oz copper. 1 2 3 5 4 sot23-5 top view run gnd sw v fb v in marking part number top mark temp range BL9310-adj i j y w (note3) -40c to +85c 1 2 3 5 4 sot23-5 top view run gnd sw v out v in marking part number top mark temp range BL9310-1.0 i a y w BL9310-1.2 i b y w BL9310-1.5 i c y w BL9310-1.8 i d y w BL9310-2.5 i e y w BL9310-3.3 i f y w -40c to +85c
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary information. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 3 BL9310 1.5 mhz, 1a synchronous buck converter pin description pin name function 1 run regulator enable control input. drive run above 1. 5v to turn on the part. drive run below 0.3v to turn it off. in shutdown, all functions are disabled drawing <1ka supply current. do not leave run float ing. 2 gnd ground 3 sw power switch output. it is the switch node connect ion to external inductor. this pin connects to the drains of the internal p-channe l and n-channel mosfet switches. 4 v in supply input pin. must be closely decoupled to gnd , pin 2, with a 2.2kf or greater ceramic capacitor. 5 v fb /v out v fb (BL9310-adj): feedback input pin. connect fb to th e center point of the external resistor divider. the regulated voltage o n this pin is 0.6v. v out (BL9310-1.2/BL9310-1.5/BL9310-1.8) : output voltage feedback pin. an internal resistive divider divides the output volta ge down for comparison to the internal reference voltage. block diagram
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 4 BL9310 1.5 mhz, 1a synchronous buck converter electrical characteristics (note 5) (v in =v run = 3.6v, ta = 25c, unless otherwise noted.) parameter conditions min typ max unit input voltage range 2.5 5.5 v input dc supply current active mode shutdown mode v fb =0.5v or v out =90% v fb =0v, v in =4.2v 200 0.1 300 1.0 ka ka t a = +25c 0.5880 0.6000 0.6120 v t a = 0c t a 85c 0.5865 0.6000 0.6135 v regulated feedback voltage t a = -40c t a 85c 0.5850 0.6000 0.6150 v v fb input bias current v fb = 0.65v 30 na reference voltage line regulation v in = 2.5v to 5.5v 0.04 0.4 %/v BL9310-1.2, -40c t a 85c 1.164 1.200 1.236 v regulated output voltage BL9310-1.8, -40c t a 85c 1.746 1.800 1.854 v ov ovl = v ovl C v fb , adjustable version 20 50 80 mv output overvoltage lockout ov ovl = v ovl C v out , fixed version 2.5 7.8 13 % output voltage line regulation v in = 2.5v to 5.5v 0.04 0.40 % output voltage load regulation 0.5 % peak inductor current v in =3v, v fb =0.5v or v out =90% duty cycle <35% 1.3 a oscillator frequency v fb =0.6v or v out =100% 1.2 1.5 1.8 mhz r ds(on) of p-ch mosfet i sw = 300ma 0.40 0.50 q r ds(on) of n-ch mosfet i sw = -300ma 0.35 0.45 q sw leakage current v run = 0v, v sw = 0v or 5v, v in = 5v 0.01 1 ka run threshold -40c t a 85c 0.3 1.1 1.30 v run leakage current 0.01 1 ka note 5: 100% production test at +25c. specifications over the temperature range are guaranteed by design and characterization.
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 5 BL9310 1.5 mhz, 1a synchronous buck converter typical performance characteristics (test figure 1 above unless otherwise specified) 0 200 400 600 800 1000 1200 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 output voltage(v) load current(ma) output voltage vs. load current v in =3.6v t a =25 c -50 -25 0 25 50 75 100 125 0.602 0.603 0.604 0.605 0.606 reference voltage(v) temperature ( c ) v in =3.6v reference voltage vs. temperature 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 5.7 1.780 1.785 1.790 1.795 1.800 1.805 1.810 1.815 1.820 v out (v) v in (v) i load =10ma i load =100ma i load =600ma output voltage vs. input voltage supply current vs. supply voltage start_up from shutdown 2 3 4 5 6 195 200 205 210 215 220 225 230 235 240 245 dynamic supply current(ua) supply voltage(v) v out =1.8v i load =0a t a =25 c 10 100 1000 20 30 40 50 60 70 80 90 efficiency (%) output current (ma) vin=2.7v vin=3.6v vin=4.2v efficiency vs. output current
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 6 BL9310 1.5 mhz, 1a synchronous buck converter load step load step load step load step pulse skipping mode output short
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary information. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 7 BL9310 1.5 mhz, 1a synchronous buck converter operation the BL9310 uses a constant frequency, current mode step-down architecture. both the main switch (p-channel mosfet) and the synchronous rectifier (n-channel mosfet) are integrated internally. this step-down dc-dc converter can supply 600ma output current over a wide input voltage range from 2.5v to 5.5v. the over voltage comparator ovdet guards against transient overshoots >7.8% by turning the main switch off and keeping it off until the fault is removed. current mode pwm control slope compensated current mode pwm control provides stable switching and cycle- by-cycle current limit for excellent load and line responses. during normal operation, the internal main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and turned off when the peak inductor current reaches the controlled value. when the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, i rcmp , or the beginning of the next clock cycle. pulse skipping mode operation at very light loads, the BL9310 will automatically enter pulse skipping mode to increase efficiency, further extending battery life. in this mode, the control loop skips pwm pulses while maintaining output in regulation, and the switching frequency depends on the load condition. this is a kind of pfm mode operation. dropout operation when the input voltage decreases toward the value of the output voltage, the BL9310 will keep the main switch on for more than one switching cycle and increases the duty cycle (note 5) until it reaches 100%. the output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. at low input supply voltage, the r ds(on) of the p-channel mosfet increases, and the efficiency of the converter decreases. caution must be exercised to ensure the heat dissipated not to exceed the maximum junction temperature of the ic. note 6 66 6 : the duty cycle d of a step-down converter is defined as: % 100 % 100 = in out osc on v v f t d where t on is the main switch on time, and f osc is the oscillator frequency (1.5mhz). short circuit protection the BL9310 has short circuit protection. when output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the pfet current limit. the pfet current limit is also reduced to lower the short circuit current. the frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6v. maximum load current the BL9310 will operate with input supply voltage as low as 2.5v, however the maximum load current decreases at lower input voltage due to large ir drop on the main switch and synchronous rectifier.
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 8 BL9310 1.5 mhz, 1a synchronous buck converter application information figure 2 below shows the basic application circuit with BL9310 fixed output versions. figure 2. basic application circuit with fixed output versions setting the output voltage figure 1 above shows the basic application circuit with BL9310 adjustable output version. the external resistor sets the output voltage according to the following equation: ) 1 2 1( 6.0 r r v v out + = table 1 resistor selection vs. output voltage setting vout r1 r2 1.0v 180 k s(1%) 120 k s(1%) 1.2v 180 k s(1%) 180 k s(1%) 1.5v 180 k s(1%) 270 k s(1%) 1.8v 180 k s(1%) 360 k s(1%) 2.5v 158 k s(1%) 499 k s(1%) 3.3v 180 k s(1%) 810 k s(1%) inductor selection the output inductor is selected to limit the ripple current to some predetermined value, typically 20%~40% of the full load current at the maximum input voltage. in continuous mode, the ripple current is determined by: ) 1( 1 in out out l v v v l f i ? = ? a reasonable starting point for setting ripple current is oi l =240ma (40% of 600ma). for output voltages above 2.0v, when efficiency at light load condition is important, the minimum recommended inductor is 2.2kh. for optimum voltage-positioning load transients, choose an inductor with dc series resistance below 150mq. for higher efficiency at heavy loads (above 200ma), or minimal load regulation (but some transient overshoot), the resistance should be kept below 100mq. the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. thus, a 720ma rated inductor should be enough for most applications (600ma+120ma). input capacitor selection the input capacitor reduces the surge current drawn from the input and switching noise from the device. the input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. in continuous mode, the source current of the main switch is a square wave of duty cycle v out /v in . to prevent large voltage transients, a low esr input capacitor sized for the maximum rms current must be used. the maximum rms capacitor current is given by: in out in out omax rms v v v v i i 5.0 )] ( [ ? this formula has a maximum at v in =2v out , where i rms = i out /2. this simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. ceramic capacitors with x5r or x7r dielectrics are recommended due to their low esr and high ripple current. output capacitor selection the output capacitor is required to keep the output voltage ripple small and to ensure
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 9 BL9310 1.5 mhz, 1a synchronous buck converter regulation loop stability. the output capacitor must have low impedance at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are recommended due to their low esr and high ripple current. the output ripple ?v out is determined by: ? ?? ? ? ?? ? + ? ? 2 8 1 ) ( c f esr l f v v v v v osc osc in out in out out efficiency considerations layout considerations when laying out the printed circuit board, the following checklist should be used to ensure proper operation of the BL9310. these items are also illustrated graphically in figures 5 and 6. check the following in your layout: 1. the power traces, consisting of the gnd trace, the sw trace and the v in trace should be kept short, direct and wide. 2. does the v fb pin connect directly to the feedback resistors? the resistive divider r1/r2 must be connected between the (+) plate of cout and ground. 3. does the (+) plate of c in connect to v in as closely as possible? this capacitor provides the ac current to the internal power mosfets. 4. keep the switching node, sw, away from the sensitive v fb node. 5. keep the (-) plates of c in and c out as close as possible. figure 3. BL9310-adj layout circuit figure 4. BL9310-1.8 layout circuit figure 5. BL9310-adj suggested layout figure 6. BL9310-1.8 suggested layout BL9310 BL9310 BL9310 BL9310- -- -adj adjadj adj BL9310 BL9310 BL9310 BL9310- -- -18 1818 18
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary information. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 10 BL9310 1.5 mhz, 1a synchronous buck converter package description dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.035 0.051 a1 0.000 0.152 0.000 0.006 b 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024 sot-23-5 surface mount package
ppmic bu www.belling.com.cn BL9310 rev 1.1 belling proprietary i nformation. unauthorized photocopy and duplication prohibited 1/2011 ?2011 belling all rights reserved 11 BL9310 1.5 mhz, 1a synchronous buck converter tsot-23-5 surface mount package

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