www.acutechnology.com AQ111 AQ111 low dropout 1 amp voltage regulator product specification revision 1.5 september 13, 2006 applications ? graphic cards ? pc motherboards ? switching power supply post-regulation ? telecom equipment ? dvd video player general description the AQ111 is a low dropout three terminal voltage regulator, offered in popular fixed options or an adjustable version that can set a precise voltage from 1.22v to 12v with two external resistors. AQ111 is the only 1 amp ldo regulator offered in the tiny psot-23 package. psot-23 is modified for lower thermal resistance and fits in the standard sot-23 foot print. with a dropout voltage of less than one volt, the AQ111 can be used in applications where drop out voltage and size are an issue. to assure accuracy within 1.5% over temperature the heart of the AQ111 is a self- correcting acuref ? bandgap reference. on-chip current limit and thermal shutdown with hysteresis protects against any combination of overload and ambient temperature that might cause the junction temperature to exceed safe limits. features ? available in the tiny psot-23 package ? vout tolerance 1.5% over temperature ? stable with low cost 1uf capacitor ? low ground current <1.5 ma ? low dropout voltage (950 mv at 1 amp) ? thermal protection with hysteresis ? short circuit protection ? offered with 1.8v, 2.5v, and 3.3v fixed or adjustable output ? rohs complaint available typical application
acutechnology semiconductor inc. AQ111 www.acutechnology.com 2 rev. 1.5 september 13, 2006 pin configuration psot-23-6 pin descriptions pin name function v in accepts + vcc v out regulated output ground/adjust - vcc for fixed option / adjust pin for adjustable option functional block diagram
acutechnology semiconductor inc. AQ111 www.acutechnology.com 3 rev. 1.5 september 13, 2006 ordering information device operating tj %tol pkg type v out wrap ordering number AQ111 0c ? 125c ? 1.0 psot-23-6 1.8v t&r AQ111cy-m7-18-tr AQ111 0c ? 125c ? 1.0 psot-23-6 1.8v t&r AQ111cy-m7-18-trl AQ111 0c ? 125c ? 1.0 psot-23-6 2.5v t&r AQ111cy-m7-25-tr AQ111 0c ? 125c ? 1.0 psot-23-6 2.5v t&r AQ111cy-m7-25-trl AQ111 0c ? 125c ? 1.0 psot-23-6 3.3v t&r AQ111cy-m7-33-tr AQ111 0c ? 125c ? 1.0 psot-23-6 3.3v t&r AQ111cy-m7-33-trl AQ111 0c ? 125c ? 1.0 psot-23-6 adj t&r AQ111cy-m7-aj-tr AQ111 0c ? 125c ? 1.0 psot-23-6 adj t&r AQ111cy-m7-aj-trl note: the trl parts are lead free and rohs compliant. absolute maximum ratings stress greater than those listed under ?absolute maximum ratings? may cause permanent damage to the device. these stress ratings only, and functional operation of the devic e at these or any conditions beyond those indicated under recommended operating conditions is not implied. exposure to ?absolute maximum rating? for extended periods may affect device reliab ility. use of standard esd handling precautions is required. parameter value units maximum v in 18 volts power dissipation (internally limited) maximum junction temperature 150 c operating junction temperature range 0 to 125 c storage temperature range -65 to 150 c lead temperature (soldering, 4sec.) sot packages 300 c thermal management thermal resistance (junction to tab) typical value units psot-23-6 (tab is pins 1,2,5, & 6) 25 c/w thermal resistance (junction to ambient) typical value units psot-23-6 (pins 1,2,5, & 6 soldered to 1 in 2 1 oz. copper pcb) 55 c/w
acutechnology semiconductor inc. AQ111 www.acutechnology.com 4 rev. 1.5 september 13, 2006 electrical specifications electrical characteristics are guaranteed over the full temperature range 0oc acutechnology semiconductor inc. AQ111 www.acutechnology.com 5 rev. 1.5 september 13, 2006 typical response curves
acutechnology semiconductor inc. AQ111 www.acutechnology.com 6 rev. 1.5 september 13, 2006 application notes 1. typical application notes: 1. output voltage is 1.22v * (r2 +r1)/r1 2. input and output capacitors should be located close to the device. 3. the AQ111 will remain stable with c1 and c2 as low as 1.0f. overall transient performance is improved with increased capacitance. 2. stability an input capacitor is recommended. a 1.0f capacitor on the input is a suitable input bypassing for almost all applications. a larger c apacitor is also suitable. in the adjustable version the ?adjust? terminal can be by passed to ground with a bypass capacitor (c adj ) to improve ripple rejection. this bypass capacitor prevents ripple from being amplified as the output voltage is increased. at any ripple frequency, the impedance of the c adj should be less than r1 (being r1 the resistor between t he output and the adjust pin) to prevent the ripple from being amplified: z = 1/(2 *f ripple * c adj ) < r1 r1 is normally in the range of 1k ? . the output capacitor is critical in maintaining regular stability. the AQ111 is stable with an output capacitor greater than. of course any increase of the output capacitor will merely improve the loop stability and the load transient response. in the case of the adjustable regulator, when the c adj is used, a larger output c apacitance may be required. tantalum capacitors exhibit the best stability over a wide range of loads and are recommended. 3. output voltage the AQ111 adjustable version develops a 1. 22v reference voltage between the output and the adjust pin terminal. this voltage is applied across the resistor r1 to generate a constant current (i1). the current from the adjust termi nal could introduce error to the output, but since it is very small (< 20a) compared with the current i1 and very constant with line and load changes, the error can be ignored. the constant current i1 then flows through resistor r2 and sets the output voltage to the desired level. for fixed voltages the resistor r1 and r2 are integrated inside the devices.
acutechnology semiconductor inc. AQ111 www.acutechnology.com 7 rev. 1.5 september 13, 2006 the AQ111 regulates the voltage that appear s between its output and ground pins or between its output and adjust pins. in some case s, line resistances can introduce errors to the voltage across the load. to obtain the bes t load regulation a few precautions are needed. for example it is important to minimize the li ne resistances to the load, so the load itself should be tied directly to the output terminal on the positive side and directly to the ground terminal on the negative side. when the adjustable regulator is used, the best performance is obtained with the positive side of the resistor r1 tied directly to the output terminal of the regulator rather than near the load. this will eliminate line drops from appearing effectively in series with the reference and degrading regulation. in addition the ground side of the resistor r2 can be returned near the ground of the load to provide remote gr ound sensing and improve load regulation. a capacitor (470pf) between the adj pin and system ground will enhance stability. 4. protection diodes unlike older regulators, the AQ111 family does not need any protection diodes between the adjustment pin and output or from the output to t he input to prevent over-stressing the die. internal resistors are limiting the internal cu rrent paths on the adjustment pin. therefore, even with capacitors on the adjustment pin, no protection diode is needed to ensure device safety under short circuit conditions. exter nal diodes between the input and output are not usually needed. only if high value output c apacitors are used (> 1000uf) and the input is instantaneously shorted to ground, can damage occur. 5. thermal considerations when an integrated circuit operates with an apprec iable current, its junction temperature is elevated. it is important to quantify its ther mal limits in order to achieve acceptable performance and reliability. this limit is determined by summing the individual parts consisting of a series of temperature rises from the semiconductor junction to the operating environment. the heat generated at the device j unction flows through the die to the die attach pad, through the lead frame to the surrounding case material, to the printed circuit board, and eventually to the ambient environment. the AQ111 regulators have internal thermal s hutdown to protect the device from over- heating. under all possible operating conditi ons, the junction temperature of the AQ111 must be lower than 125c. a heatsink may be required depending on the maximum power dissipation and maximum ambient te mperature of the application. to determine if a heatsink is needed, t he power dissipated by the regulator, p d , must be calculated: p d = (v in -v out ) i l where the i l is the load current. the next parameter which must be calculated is the maximum allowable temperature rise, t(max): t(max)=t j (max)-t a (max) where t j (max) is the maximum allowable junction temperature (125c), and t a (max) is the maximum ambient temperature which will be encountered in the application. using the calculated values for t(max) and p d , the maximum allowable value for the junction to ambient thermal resistance ( ja ) can be calculated: ja =t(max)/ p d if the maximum allowable value for ja is found to be greater than the junction to ambient thermal resistance for the package used, no heatsink is needed since the package alone will dissipate enough heat to satisfy these requirements. package dimensions
acutechnology semiconductor inc. AQ111 www.acutechnology.com 8 rev. 1.5 september 13, 2006
acutechnology semiconductor inc. AQ111 www.acutechnology.com 9 rev. 1.5 september 13, 2006 contact information acutechnology semiconductor inc. tel: (408) 259-2300 3487 mckee rd. suite 52 fax: (408) 259-9160 san jose ca , usa 95127 website: www.acutec hnology.com disclaimer the information furnished by acutechnology in this data s heet is believed to be accurate and reliable. however, acutechnology assumes no responsibility for it s use. acutechnology reserves the right to change circuitry and specifications at any time without notific ation to the customer. life support policy acutechnology products are not designed or authorized for use as components in life support devices or systems where malfunction of a product can reasonably be ex pected to result in personal injury. life support devices or systems are devices or systems that (a) are intended fo r surgical implant into the body or (b) support or sustain life, and whose failure t o perform can be reasonably expected to result in a significant injury to the user. acuref ? is a trademark of acutechnology semiconductor inc
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