features ? wide 3.6v to 25v input voltage range ? output adjustable from 0.8v to 24v ? maximum duty cycle 100% ? minimum drop out 0.6v ? fixed 360khz switching frequency ? 5a constant output current capability ? internal optimize power mosfet ? high e fficiency up to 85~90% ? excellent line and load regu lation ? ttl shutdown capability ? en pin with hysteresis function ? built in thermal shutdown function ? built in current limit f unction ? built in output short p rotection function ? package in to-263/to252 and to220 applications ? lcd monitor and lcd tv ? to220 can supply 5a continues ? to263 can supply 5a , to252 can supply 4a ? adsl modem ? telecom / networking equipment general description the ams2566 is a 360 khz fixed frequency pwm buck (step-down) dc/dc converter, capable of driving a 5a load with high efficiency, low ripple and excellent line and load regulation. requiring a minimum number of external components, the regulator is sim ple to use and include internal frequency compensation and a fixed-frequency oscillator. the pwm control circuit is able to a djust the duty ratio linearly from 0 to 100%. an enable function, an over current protection function is built inside. when short protection function happens, the operation f requency will be reduced from 360khz to 70khz. an internal com pensation block is built in to m inim ize external component count.
pin configurations for to263/to220/to252 : important note : pin3 sw is shorted to tab (heat -sink is not ground) t able 1 pin description pin number pin name description 1 gnd ground pin. care m ust be taken in layout. this pin should be placed outside of the schottky diode to output capacitor ground path to prevent switching current spikes from inducing voltage noise into ams2566. 2 fb feedback pin (fb). through an external resistor divider network, fb senses the output voltage and regulates it. the feedback threshold voltage is 0.8v. 3 sw power switch output pin (sw ). sw is the switch node that supplies power to the output. 4 en enable pin. drive en pin high to turn on the device, drive it low to turn it off. floating is default high. 5 vin supply voltage input ams2566 operates from a 3.6v to 25v dc voltage. bypass vin to gnd with a suitably large capacitor to eliminate noise on the input.
function block figure3. function block diagram of ams2566 t ypical application circuit
ordering information part number fact lead free lead free voltage AMS2566-XX to263-5/to252-5 xx package temperature range ams25 66 l-xx to220-5 (two lines, two pins back three front) xlsemi pb-free products, as des ignated with ?e1? suffix in the p ar number, are rohs complian t. absolute maximum ratings
electrical characteristics t a = 25 system parameters test circuit figure4 vfb feedback voltage vin = 5v to 25v, vout=5v iload=0.5a to 5a 0.776 0.8 0.824 v efficiency ?
test circuit and layout guidelines figure5. standard test circuits and layout guides select r1 to be approximately 2k, us e a 1% resistor for best stability. c1 and cff are optional; in order to increase stability and reduce the input power line noise, cin and c1 must be placed near to pin1 and pin3; for output voltages greater than approximately 10 v, an additional capacito r cff is required. the compensation capacitor is typically between 100 pf and 33 nf, and is wired in parallel with the output voltage setting resistor, r2. it provides additional stab ility for high output voltage, low input-output voltages, and/or very low esr output capacito rs, such as solid tantalum capacitors. cff=1/(31*1000*r2); this capacitor type can be ceramic , plastic, silver mica, etc. (because of the unstable characteristics of ceramic capacito rs made with z5u material, they are not recommended.)
schottky diode selection t able current surface mount through hole vr (the same as system maximum input voltage) 20v 30v 40v 50v 60v 1a 1n5817 1n5818 1n5819 1n5820 1n5821 1n5822 mbr320 mbr330 mbr340 mbr350 mbr360 sk32 sk33 sk34 sk35 sk36 30wq03 30wq04 30wq05 31dq03 31dq04 31dq05 3a sr302 sr303 sr304 sr305 sr306 1n5823 1n5824 1n5825 sr502 sr503 sr504 sr505 sr506 sb520 sb530 sb540 sb550 sb560 5a 50wq03 50wq04 50wq05
t ypical system application for 24v ~ 12v/3a version figure6. ams2566 system param eters test circuit (24v ~ 12v/3a) t ypical system application for 24v ~ 5v/5a figure7. ams2566 system param eters test circuit (24v ~ 5v/5a)
package information: (1 ) to263-5l bookly micro 2 (2) to220-5 is 3pins front and 2 back same as bm2596-l so , it will not be described here .
(3) package information to2 5 2-5l
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