unisonic technologies co., ltd UC1100 preliminary cmos ic www.unisonic.com.tw 1 of 6 copyright ? 2015 unisonic technologies co., ltd qw-r129-007.a low-power high precision cc/cv primary side switching regulator ? description the utc UC1100 is a primary control unit for switch mode charger and adapter applications. the controlled variable is transferred by an auxiliary winding from the secondary to the primary side. the device uses pulse frequency modulation (pfm) method to build discontinuous conduction mode (dcm) flyback power supplies. the utc UC1100 operates in primary-side sensing and regulation. opto-coupler and t l431 could be eliminated. it also eliminates the need of loop compensation circuitry while maintaining stability. the utc UC1100 achieves excellent regulation and high average efficienc y, yet meets the requirement for no-load consumption less than 30mw. the utc UC1100 achieves high precision cv/cc regulation and high power efficiency. it offers comprehensive protection coverage with auto-recovery features including cycle-by-cycle current limiting, output over vo ltage protection, feedback loop open protection, short circuit protec tion, leading edge blanking, v cc under voltage lockout, etc. ? features sot-26 4 5 3 2 1 6 * primary side control for rectangular constant current and constant voltage output * 30mw no-load input power feasible * tight cc regulation performance * sub-microampere start-up current * eliminates control loop compensation circuitry * eliminates opto-coupler and secondary cv/cc control circuitry * random frequency modulation to reduce system emi * flyback topology in dcm operation * open feedback protection * built-in soft start * short circuit protection ? ordering information ordering number package packing UC1100g-ag6-r sot-26 tape reel
UC1100 preliminary cmos ic unisonic technologies co., ltd 2 of 6 www.unisonic.com.tw qw-r129-007.a ? marking information ? pin configuration ? pin description pin no. pin name description 1 out this pin drives the base of external power npn switch 2, 5 gnd ground 3 v cc supply voltage 4 cs the primary current sense 6 fb the voltage feedback from the auxiliary winding ? block diagram
UC1100 preliminary cmos ic unisonic technologies co., ltd 3 of 6 www.unisonic.com.tw qw-r129-007.a ? absolute maximum rating parameter symbol ratings unit supply voltage v cc -0.3~36 v voltage at cs, out to gnd -0.3~7 v fb input -40~10 v output current at out internally limited a esd (machine model) 200 v esd (human body model) 1 000 v operating junction temperature t opr 150 c storage temperature t stg -65~150 c note: absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? thermal resistance s characteristics parameter symbol ratings unit junction to ambient ja 250 c/w ? electrical characteristics (v cc =15v, t a =25c, unless otherwise specified.) parameter symbol test conditions min typ max unit uvlo section start-up threshold v th (st) 16 18.5 21 v minimal operating voltage v opr (min) 7.2 9 10.2 v standby current section start-up current i st v cc =v th (st) -0.5v, before start-up 3 a operating current i cc(opr) static 350 400 a drive output section sink 50 ma out maximum current source i out 40 60 80 ma current sense section current sense threshold v cs 455 510 545 mv equivalent current sense voltag e accuracy eq , v eq , v ? cs cs note 1 3 % pre-current sense v cs(pre) 365 410 455 mv leading edge blanking 500 ns feedback input section feedback pin input leakage current i fb v fb =4v 2.0 2.5 3.1 a feedback threshold v fb 3.59 3.83 4.07 v note: the output current is given by s p cs cs out n n r eq , v = i
UC1100 preliminary cmos ic unisonic technologies co., ltd 4 of 6 www.unisonic.com.tw qw-r129-007.a ? operation description the utc UC1100 is a primary control unit for switch mode char ger and adapter applications. it operates in primary-side sensing and regulation. opto-coupler and tl43 1 could be eliminated. proprietary built-in cv and cc control can achieve high precision cv/cc performance. it uses pulse frequency modulation (pfm) method to build discontinuous conduction mode (dcm) flyback power supplies. startup control the v cc pin of utc UC1100 is connected to the line input through a resi stor. a large value startup resistor can be used to minimize the power loss in applic ation because the start current of utc UC1100 is very low. when the v cc voltage reaches v th (st) , the internal startup circuit is disabled and the ic turns on. operating current the operating current of utc UC1100 is as low as 320ua. good efficiency and very low standby power can be achieved. constant voltage operation the output voltage is defined by the transmission ratio between the secondary and auxiliary winding. the utc UC1100 captures the auxiliary winding feedback voltage at fb pin and operates in const ant-voltage (cv) mode to regulate the output voltage. the auxiliary voltage reflects the output voltage is given by: v ? + v n n = v o s a aux (1) w here v indicates the drop volt age of the output diode. figure1. auxiliary voltage waveform via a resistor divider connected between the auxiliary winding and fb, the v aux is sampled at the tsampling end and it is hold until the next sampling. the sampled voltage is compared with 4v reference voltage and the error is amplified. the error amplifier output re flects the load condition and controls the toff time to regulate the output voltage, thus constant output voltage can be achieved. constant current operation when the sampled voltage is below 4v reference voltage a nd the error amplifier output reaches its maximum, thus utc UC1100 operates in constant-current ( cc) mode. the cc point and maximum output power can be externally adjusted by external current sense resistor rcs. the larg er rcs, the smaller cc point is, and the smaller output power becomes.
UC1100 preliminary cmos ic unisonic technologies co., ltd 5 of 6 www.unisonic.com.tw qw-r129-007.a ? operation description (cost.) figure2. adjustable output power by changing rcs figure3. secondary current waveform in cc operation, the cc loop control function of utc UC1100 will keep a fixed proportion between secondary inductance de-magnetization time (tdemag) and switch ing cycle time (tsw). the fixed proportion is 7 4 = tsw tdemag (2) thus the output current is given by: ipk n n 7 2 = tsw tdemag ipk n n 2 1 = iout s p s p (3) current sensing and leading edge blanking cycle-by-cycle current limiting is offered in utc UC1100 . the switch current is detected by a sense resistor into the cs pin. when the power switch is turned on, a turn-on spike will occur on this resistor. a 750ns leading-edge blanking is built in to avoid false-termi nation of the switching puls e so that the external rc filtering is no longer needed. drive bjt the driver is a push pull stage with the supply voltage v cc . it provides the driving current for the external power bipolar transistor. the output signal is current-limited to i out(source) . protection control good power supply system reliability is achieved with its comprehensive protection features including output over-voltage protection, feedback loop open protection, cycl e-by-cycle current limiting, short circuit protection, leading edge blanking and uvlo, etc. v cc is supplied by transformer auxiliary winding output. the output of utc UC1100 is shutdown when v cc drops below v opr(min) and the power converter enters power on start-up sequence thereafter.
UC1100 preliminary cmos ic unisonic technologies co., ltd 6 of 6 www.unisonic.com.tw qw-r129-007.a ? typical application circuit v cc gnd gnd fb u1 2 3 6 3 bd1 4 2 1 f1 l n 5 21v/0.3a l1 c1 + 12 c2 + r1 r2 c3 + r3 r6 d2 r12 r5 r4 d1 c4 c7 out cs 1 4 r10 r8 r11 q1 4 3 2 t1 5 r13 d3 a b c5 c6 + r14 cy1 gnd 1 bom reference component reference component f1 0.5a/250v u1 UC1100, sot-26 bd1 b6s r1, r2 1m ? 1206 c1, c2 ec 4.7 f/400v 105c r3 1.5m ? 1206 c3 ec 4.7 f/50v 105c r4 200k ? 1206 c4 cc 102p/1kv r5 22 ? 0805 c5 nc r6 3.9 ? 0805 c6 ec 220 f/35v 105c r8 940m ? 1206 c7 nc r10 20k ? 0805 l1 1.2mh r11 4.3k ? 0805 t1 ee-16 r12 1k ? 0805 d1 1n4007, sma r13 nc d2 bav21, sod-123 r14 24k ? 1206 d3 mgbr3200, do-201ad cy1 y1 102p/400v q1 mje13003, to-126 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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