dc-to-dc converter control circuits MC34063A general description outline drawing the MC34063A is a monolithic control circuit containing the primary functions required for dc-to-dc converters. these devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. this series was specifically designed to be incorporated in step-down and step-up and voltage- inver ting applications with a minimum number of external components. features z operation from 3.0v to 40v input z low standby current z current limiting z output switch current to 1.2a z output voltage adjustable z frequency operation to 100khz z precision 2% reference dip8 sop8 tiger electronic co.,ltd
MC34063A block diagram pin connection maximum ratings (ta=25 c) rating symbol value unit power supply voltage vcc 40 v comparator input voltage range v ir 0.3~40 v switch collector voltage vc(switch) 40 v switch emitter voltage (v p in 1 =40v) v e (switch) 40 v switch collector to emitter voltage v ce (switch) 40 v driver collector voltage vc(drive) 40 v driver collector current (note 1) ic(drive) 100 ma switch current i sw 1.2 a dip8 1.25 w power dissipation sop8 p d 625 mw operating ambient temperature range ta 0~70 c storage temperature range tstg -65~150 c notes: 1.maximum package power di ssipation limits must be observed 2.esd data available upon request 1 2 3 4 5 6 7 8 switch switch timing groun d drive ipk vcc comparato r MC34063A ollecto r inverting collecto r input apacito r emitter
MC34063A electrical characteristics (unless otherwise specified: vcc=5.0v, ta=0~70 c) characteristics symbol min typ max unit oscillator frequency (vpin5=0v, vcc=5.0v) fosc 24 33 42 khz charge current (vcc=5.0~40v, vpin3=l) ichg 24 31 42 a discharge current (vcc=5.0~40v, vpin3=h) idischg 140 199 260 a discharge to charge current ratio (v pin7 =v cc , ta=25 c) idischg/ichg 5.2 6.2 7.5 current limit sense voltage (ichg=idischg, ta=25 c) vipk(sense) 250 300 350 mv output switch (note 3) saturation voltage, darlington connection(note 4) (i sw =0.8a, pins 1,8 connected) v ce (sat) 0.9 1.3 v saturation voltage, darlington connection (i sw =0.8a, rpin 8=82 ? to vcc) v ce (sat) 0.45 0.7 v dc current gain (i sw =0.8a,v ce =5.0v, ta=25 c) h fe 50 120 collector off-state current (v ce =40v) ic(off) 2 100 a comparator threshold voltage (ta=25 c, vcc=5.0v) vth 1.23 1.25 1.27 v threshold voltage line regulation (vcc=5.0~40v) regline 4.0 5.0 mv input bias current(vin=0v) i ib -40 -400 na total device supply current (vcc=5.0~40v, vpin5 =h) icc 2.36 4.0 ma notes: 3. low duty cycle pulse techniques are used duri ng test to maintain junction temperature as close to ambient temperature as possible. 4. if the output switch is driven into hard saturation (non-darlington configuration) at low switch currents ( 300 ma) and high driver currents ( 30 ma), it may take up to 2.0 s for it to come out of saturation. this condition will shorten the off time at frequencies 30 khz, and is magnified at high temperatures. this condition doe s not occur with a darlington configuration, since the output switch cannot saturate. if a non-da rlington configuration is used, the following output drive condition is recommended: forced of output switch : ic output/ (ic drive ?7.0ma)* 10 *the 100 ? resistor in the emitter of the driver devi ce requires about 7.0 ma before the output switch conducts.
MC34063A application circuits 1.step-up converter test conditions results line regulation vin=8.0~16v, io=175ma 30mv=0.05% load regulation vin=12v,io=75~175ma 10mv=0.017% output ripple vin=12v, io=175ma 400mvpp efficiency vin=12v, io=175ma 87.7% output ripple with optional filter vin=12v, io=175ma 40mvpp 2.external current boost connections for ic peak greater than 1.5a (1).external npn switch (2 ) external npn saturated switch (note 4)
MC34063A 3.step-down converter test conditions results line regulation vin=15~25v, io=500ma 12mv=0.12% load regulation vin=25v,io=50~500ma 3.0mv=0.03% output ripple vin=25v, io=500ma 120mvpp short circuit current vin=25v,rl=0.1 ? 1.1a efficiency vin=25v, io=500ma 83.7% output ripple with optional filter vin=25v, io=500ma 40mvpp 4.external current boost connections for ic peak greater than 1.5a (1).external npn switch (2) external npn saturated switch
MC34063A 5. voltage inverting converter test conditions results line regulation vin=4.5~6.0v, io=100ma 3.0mv=0.012% load regulation vin=5.0v,io=10~100ma 3.0mv=0.09% output ripple vin=5.0v, io=100ma 500mvpp short circuit current vin=5.0v,rl=0.1 ? 910ma efficiency vin=5.0v, io=100ma 62.2% output ripple with optional filter vin=5.0v, io=100ma 70mvpp 6.external current boost connections for ic peak greater than 1.5a (1).external npn switch (2) external npn saturated switch
MC34063A characteristics curves output switch on-off time versus timing capacitor waveform oscillator timing capacitor emitter follower configuration output common emitter co nfiguration output saturation voltage versus emitter switch saturation voltage versus current collector current current limit sense voltage versus standby supply current versus temperature supply voltage
MC34063A marking information outline drawing dip8 unit:mm
MC34063A sop8 unit:mm
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