unisonic technologies co., ltd l2800 linear integrated circuit www.unisonic.com.tw 1 of 7 copyright ? 2013 unisonic technologies co., ltd qw-r103-030.c switching regulator controller(low voltage) ? description the utc l2800 which is incorporating a soft start function and short circuit detection function is a single-channel switching regulator control ic and is m ade for low voltage applications. because the device has a low mini mum operating voltage of 1.8v, so it is ideal for the power s upply of battery-operated electronic equipment. ? features *wide supply voltage operat ing range: 1.8v~15v *low current consumption: ty pically 5.5ma in operation,1 a or less in stand-by *high speed operation is possible: maximum 1mhz *the error amplifier gain is set inside the ic, so peripheral components are minimized. *incorporates a soft start circuit. *incorporates a timer-lat ch type short circuit detection circuit (scp). *totem-pole type output with adj ustable on/off current (for npn transistors) *incorporates a stand-by function. sop-8 tssop-8 ? ordering information ordering number package packing lead free halogen free l2800l-s08-t l2800g-s08-t sop-8 tube L2800L-S08-R l2800g-s08-r sop-8 tape reel l2800l-p08-t l2800g-p08-t tssop-8 tube l2800l-p08-r l2800g-p08-r tssop-8 tape reel
l2800 linear integrated circuit unisonic technologies co., ltd 2 of 7 www.unisonic.com.tw qw-r103-030.c ? pin configuration ? pin description pin no. symbol i/o description 1 -in i error amplifie r inverting input pin 2 scp - soft start and scp setting capacitor connection pin 3 vcc - power supply pin 4 br/ctl i output current setting and control pin 5 out o totem-pole type output pin 6 gnd - ground pin 7 osc - capacitor and resistor connection pin for setting the oscillation frequency 8 fb o error amplifier output pin ? block diagram
l2800 linear integrated circuit unisonic technologies co., ltd 3 of 7 www.unisonic.com.tw qw-r103-030.c ? absolute maximum ratings (t a =25 ? c) parameter symbol ratings unit power supply voltage v cc 16 v output source current i o + -50 ma output sink current i o - 50 ma power dissipation (note2) sop-8 p d 570 mw tssop-8 580 storage temperature t stg -55 ~ +125 ? c operating temperature t opr -30 ~ +85 ? c notes: 1. absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings onl y and functional device oper ation is not implied. 2. when mounted on a 10cm square double-sided epoxy board. ? recommended operating conditions (t a =25 ? c) parameter symbol min typ max unit power supply voltage v cc 1.8 15 v error amplifier input voltage v i -0.2 1.0 v br/ctl pin input voltage v br -0.2 v cc v output source current i o + -40 ma output sink current i o - 40 ma scp pin capacitance c pe 0.1 f phase compensation capacitance c p 0.1 f output current setting resistance r b 150 390 5000 ? timing resistance r t 1.0 3.0 10.0 k ? timing capacitance c t 100 270 10000 pf oscillation frequency f osc 10 500 1000 khz operating temperature t opr -30 +25 +85 ? c
l2800 linear integrated circuit unisonic technologies co., ltd 4 of 7 www.unisonic.com.tw qw-r103-030.c ? electrical characteristics (t a =25 ? c, v cc =+2v) parameter symbol test conditions min typ max unit circuit to prevent malfuncition at low input oltage (u.v.l.o) reset voltage v r 0.9 v threshold voltage v th 1.1 1.3 1.5 v soft start charging current i cs v scp =0v -1.5 -1.0 -0.7 a voltage at soft start completion v ts 0.7 0.8 0.9 v short circuit detection(s.c.p.) charging current i cpc v scp =0v -1.5 -1.0 -0.7 a threshold voltage v tpc 0.7 0.8 0.9 v sawtooth wave oscillator(osc) oscillation frequency f osc r t =3.0k ? , c t =270pf 400 500 600 khz frequency input stability f dv v cc =2v ~ 15v 2 10 % frequency variation with temperature f dt t a =-30 ? c ~ +85 ? c 5 % error amplifier input threshold voltage v t v fb =450mv 480 500 520 mv v t input stability v tdv v cc =2v ~ 15v 5 20 mv v t variation with temperature v tdt t a = -30 ? c ~ +85 ? c 1 % input bias current i b v in =0v -1.0 -0.2 1.0 a voltage gain av 70 100 145 v/v frequency bandwidth bw a v =0db 6 mhz maximum output voltage range v om + 0.78 0.87 v v om - 0.05 0.2 v output source current i om + v fb =0.45v -40 -24 a output sink current i om - 24 40 a idle period adjustment section maximum duty cycle t duty r t =3.0k ? , c t =270pf, v fb =0.8v 65 75 85 % output section output voltage v oh1 r b =390 ? , i o =-15ma 1.0 1.2 v v oh2 r b =750 ? , v cc =1.8v, io= -10ma 0.8 1.0 v v ol1 r b =390 ? , i o =15ma 0.1 0.2 v v ol2 r b =750 ? , v cc =1.8v, io=10ma 0.1 0.2 v output source current i o + r b =390 ? , v o =0.9v -30 -20 ma output sink current i o - r b =390 ? , v o =0.3v 30 60 ma pull down resistance r o 20 30 40 k ? output current setting section/control section pin voltage v br r b =390 ? 0.2 0.3 0.4 v input off condition i off -20 0 a input on condition i on -45 a pin current range i br -1.8 -0.1 ma entire device stand-by current i ccs br/ctl pin open or v cc 1 a average supply current i cc r b =390 ? 5.5 9.3 ma
l2800 linear integrated circuit unisonic technologies co., ltd 5 of 7 www.unisonic.com.tw qw-r103-030.c ? diagram ? how to set the time constant for short circuit detection and soft start 1. short circuit protection te error amplifier output (f b pin) is fixed at vom + and capacitor c pe starts charging i t he switching regulator output suddenly drops due to load effe ct. the output pin is set low and the scp pin stays low when the voltage at the scp pin reaches approximately 0.8v. as the protection circuit operates, by resetting the power supply the circuit will be restored. ?short circuit detection time t pe P [s] 0.8c pe [ f] 2. soft start once power on, the capacitor c pe which is connected to the scp pin starts charging.the soft start setting voltage is compared by the pwm com parator as the voltage?s proportion at the scp pin with the sawtooth waveform. the comparison controls the out pin?s on dut y,which is causing the soft start operation. during the time for completion of soft start operation, the scp pin?s voltage stays low, but the soft start setting voltage stays high, and the circuit then enters the output short circ uit detection wait state. soft start time (until the output on duty reaches approximately 50%) P ts[s] 0.35c pe [ f]
l2800 linear integrated circuit unisonic technologies co., ltd 6 of 7 www.unisonic.com.tw qw-r103-030.c ? application example 18k br/ctl scp gnd fb -in vcc osc out v o 5v 22 h 10 f 0.1 f 3k 270pf 390 0.1 f 2k 33 f v in 3v ctl 4 1 2 3 5 6 7 8
l2800 linear integrated circuit unisonic technologies co., ltd 7 of 7 www.unisonic.com.tw qw-r103-030.c ? typical characteristics utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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