preliminary rt9182 ds9182-05 february 2003 www.richtek.com 1 dual, low-noise, 200ma ldo regulator general description the rt9182 is a dual-channel, low noise, and low dropout regulator supplying up to 200ma current at each channel. the output voltage ranges from 1.5v to 3.3v in 100mv increments and 2% accuracy by operating from a +2.7v to +5.5v input. the rt9182 uses an internal pmos as the pass device, which consumes 165 a supply current (both ldos on) independent of load current and dropout conditions. the shdn1 and shdn2 pins control each output respectively. when both outputs shutdown simultaneously, the chip will be turn off and consumes nearly zero operation current which is suitable for battery-power devices. other features include a current limiti ng, and over temperature protection. ordering information rt9182 marking information for marking information, contact our sales representative directly or through a richtek distributor located in your area, otherwise visit our website for detail. features ? up to 200ma output current (each ldo) ? dual shutdown pins control each output ? 124 v rms low noise output ? current limiting and thermal protection ? short circuit protection ? 120mv dropout at 100ma load ? two ldos in sot-26 package applications cellular phones laptop, notebook, and palmtop computers battery-powered equipment hand-held equipment wireless lan pin configurations part number pin configurations rt9182 ces (plastic sot-26) top view 1. vout2 2. gnd 3. shdn2 4. shdn1 5. vin 6. vout1 typical application circuit operating temperature range c : commercial standard package type es : so t -26 output voltage a : 2.8v (output1), 2.8v (output2) b : 3.0v (output1), 3.0v (output2) c : 2.8v ( out p ut1 ), 3.0v ( out p ut2 ) 64 3 2 1 5 vout1 vo ut2 rt9182 shdn2 vin gnd 2.2 f 2.2 f 2.2 f v in v out2 v out1 shdn1 on off on off
rt9182 preliminary www.richtek.com ds9182-05 february 2003 2 vout2 + _ + _ vref bias thermal protection current limit current limit gnd shdn2 vin vout1 shdn1 pin description pin no. pin name pin function 1 vout2 channel 2 output voltage 2 gnd common ground 3 shdn2 note channel 2 shutdown input logic, active low. if the shutdown feature is not required, connect shdn2 to vin. 4 shdn1 note channel 1 shutdown input logic, active low. if the shutdown feature is not required, connect shdn1 to vin. 5 vin supply input 6 vout1 channel 1 output voltage note: active low shutdown. if shdn1 and shdn2 are bot h low, both regulators and the reference turn off. function block diagram
preliminary rt9182 ds9182-05 february 2003 www.richtek.com 3 absolute maximum ratings supply input voltage 6.5v power dissipation, p d @ t a = 25 c sot-26 748mw lead temperature (soldering, 10 sec.) 260 c junction temperature 125 c storage temperature range ? 65 c to 150 c recommended operating conditions (note 1) supply input voltage 2.7v to 5.5v shutdown input voltage 0v to 5.5v junction temperature range ? 40 c to 85 c electrical characteristics (v in = 3.6v, c in = c out = 2.2 f, shdn = shdn1 = shdn2 = v in , typical values at t a = 25 c, for each ldo unless otherwise specified.) parameter symbol test conditions min typ max units output voltage accuracy (load regulation) ? v out i l = 1ma to 200ma -2 -- +2 % maximum output current i max continuous 200 -- -- ma current limit i limit r load = 1 ? 500 -- 1000 ma no load -- 165 260 a gnd pin current i g i out = 100ma (both ldos) -- 165 260 a i out = 1ma -- 1.2 -- mv i out = 100ma -- 120 -- mv dropout voltage (note 2) v drop i out = 200ma -- 255 -- mv line regulation ? v line v in = (v out +0.4v or 2.7v) to 5.5v i out = 1ma -0.2 -- +0.2 %/v shdn input high threshold v ih v in = 2.7v to 5.5v 1.6 -- -- v shdn input low threshold v il v in = 2.7v to 5.5v -- -- 0.4 v shdn input bias current i sd shdn = gnd or v in -- -- 100 na shutdown supply current i gsd shdn1 = shdn2 = gnd -- 0.01 2 a thermal shutdown temperature t sd -- 140 -- c thermal shutdown hysteresis ? t sd -- 10 -- c output voltage noise e no 10hz to 100khz, c out = 4.7 f, i load = 1ma -- 124 -- v rms output voltage ac psrr 100hz, c out = 4.7 f, i load = 100ma -- 62 -- db note 1. the device is not guaranteed to f unction outside its operating conditions note 2. dropout voltage definition: v in ? v out when v out is 50mv below the value of v out (normal)
rt9182 preliminary www.richtek.com ds9182-05 february 2003 4 typical operating characteristics v out = 2.8v, i load = 100ma, v in = 3.6v, c out = 4.7 f, and c in = 2.2 f, unless otherwise noted. quiescent current vs. supply voltage 0 40 80 120 160 200 240 2.5 3.5 4.5 5.5 6.5 supply voltage (v) quiescent current ( a) no load i load = 100ma, both out p uts dropout voltage vs. temp. 0 50 100 150 200 250 300 -40 -15 10 35 60 85 temperature ( c) dropout voltage (mv) i load = 200ma quiescent current vs. temp. 0 25 50 75 100 125 150 175 200 -40 -15 10 35 60 85 temperature ( c) quiescent current ( a) channel-to-channel isolation vs. frequency 0 20 40 60 80 100 120 frequency (hz) channel isolation (db) r load = 100 ? 100 1k 10k 100k 1m quiescent current vs. load current 0 30 60 90 120 150 180 0 40 80 120 160 200 load current (ma) quiescent current ( a) ( a ) both outputs loaded output voltage accuracy vs. temp. -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 -40 -15 10 35 60 85 temperature ( c) output voltage (%)
preliminary rt9182 ds9182-05 february 2003 www.richtek.com 5 t t t 1 > 2 > 5v/div 1v/div shutdown response 1ms/div time shutdown voltage out p ut volta g e i load = 50ma t t t 1 > 2 > 100ma/div 50mv/div load transient response (i load = 0 to 80ma) 10 s/div time load current output voltage deviation ( a c - coup l ed) t t t 1 > 2 4.5 3.5 20mv/div line transient response 50 s/div time input voltage (v) output voltage deviation ( ac-cou p led )
rt9182 preliminary www.richtek.com ds9182-05 february 2003 6 functional description the rt9182 is integrated with two low noise, low dropout, and low quiescent current linear regulators designed primarily for battery-powered applications. output voltages are optional ranging from 1.5v to 3.3v, and each channel can supply current up to 200ma. shutdown the rt9182 is shutdown by pulling the shdn input low, and turned on by driving the input high. if this feature is not to be used, the shdn input should be tied to vin to keep the regulator on at all times (the shdn input must not be left floating). internal p-channel pass transistor the rt9182 features double typical 1.5 ? p-channel mosfet pass transistors. it provides several advantages over similar designs using pnp pass transistors, including longer battery life. the p- channel mosfet requires no base drive, which reduces quiescent current considerably. pnp-based regulators waste considerable current in dropout when the pass transistor saturates. they also use high base-drive currents under large loads. the rt9182 does not suffer from these problems and consume only 165 a of quiescent current whether in dropout, light-load, or heavy-load applications. current limit and thermal protection the rt9182 includes two independent current limit structure which monitor and control each pass transistor?s gate voltage limiting the guaranteed maximum output current to 200ma minimum. thermal-overload protec tion limits total power dissipation in the rt9182. when the junction temperature exceeds t j = +140c, the thermal sensor signals the shutdown logic turning off the pass transistor and allowing the ic to cool. the thermal sensor will turn t he pass transistor on again after the ic?s junction temperature cools by 10c, resulting in a pulsed output during continuous thermal-overload conditions. thermal-overloaded protection is designed to protect the rt9182 in the event of fault conditions. do not exceed the absolute maximum junction-temperature rating of t j = +150c for continuous operation. the output can be shorted to ground for an indefinite amount of time without damaging the part by cooperation of current limit and thermal protection. operating region and power dissipation the maximum power dissipation of rt9182 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. the power dissipation across the device is p = i out (v in - v out ). the maximum power dissipation is: pmax = (t j - t a ) / ja where t j - t a is the temperature difference between the rt9182 die junction and the surrounding environment, ja is the thermal resistance from the junction to the surrounding environment. the gnd pin of the rt9182 performs the dual function of providing an electrical connection to ground and channeling heat away. connect the gnd pin to ground using a large pad or ground plane.
preliminary rt9182 ds9182-05 february 2003 www.richtek.com 7 applications information capacitor selection and regulator stability like any low-dropout regulator, the external capacitors used with the rt9182 must be carefully selected for regulator stability and performance. using a capacitor whose value is > 1 f on the rt9182 input and the amount of capacitance can be increased without limit. the input capacitor must be located a distance of not more than 0.5" from the input pin of the ic and returned to a clean analog ground. any good quality ceramic or tantalum can be used for this capacitor. the capacitor with larger value and lower esr (equivalent series resistance) provides better psrr and line-transient response. the output capacitor must meet both requirements for minimum amount of capacitance and esr in all ldo applications (see fig.1). the rt9182 is designed specifically to work with low esr ceramic output capacitor in space-saving and performance consideration. using a ceramic capacitor whose value is at least 1 f with esr is > 5m ? on the rt9182 output ensures stability. the rt9182 still works well with output capacitor of other types due to the wide stable esr range. output capacitor of larger capacitance can reduce noise and improve load- transient response, stability, and psrr. the output capacitor should be located not more than 0.5" from the v out pin of the rt9182 and returned to a clean analog ground. note that some ceramic dielectrics exhibit large capacitance and esr variation with temperature. it may be necessary to use 2.2 f or more to ensure stability at temperatures bel ow -10c in this case. also, tantalum capacitors, 2.2 f or more may be needed to maintain capacitance and esr in the stable region for strict application environment. tantalum capacitors maybe suffer failure due to surge current when it is connected to a low- impedance source of power (like a battery or very large capacitor). if a tantalum capacitor is used at the input, it must be guaranteed to have a surge current rating sufficient for the application by the manufacture. load-transient considerations the rt9182 load-transient response graphs show two components of the output response: a dc shift from the output impedance due to the load current change, and the transient response. the dc shift is quite small due to the excellent load regulation of the ic. typical output voltage transient spike for a step change in the load current from 0ma to 50ma is tens mv, depending on the esr of the output capacitor. increasing the output capacitor?s value and decreasing the esr attenuates the overshoot. input-output (dropout) voltage a regulator?s minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. in battery-powered systems, this will determine the us eful end-of-life battery voltage. because the rt9182 uses a p-channel mosfet pass transistor, the dropout voltage is a function of drain-to-source on-resistance [r ds(on) ] multiplied by the load current. fig. 1 c out = 4.7 f c out = 1 f ? region of stable c out esr vs. load current load current (ma) c out esr ( ? ) 0 40 80 120 160 200 100 10 1 0.1 0.01 0.001 (m ? ) ?
rt9182 preliminary www.richtek.com ds9182-05 february 2003 8 v in v out reverse current path the power transistor used in the rt9182 has an inherent diode connected between each regulator input and output (see fig.2). if the output is forced above the input by more than a diode-drop, this diode will become forward biased and current will flow from the v out terminal to v in . this diode will also be turned on by abruptly stepping the input voltage to a value below the output volt age. to prevent regulator mis-operation, a schottky diode could be used in the applications where input/output voltage conditions can cause the internal diode to be turned on (see fig.3). as shown, the schottky diode is connected in parallel with the internal parasitic diode and prevents it from being turned on by limiting the voltage drop across it to about 0.3v < 100ma to prevent damage to the part. fig. 2 fig. 3 v in v ou t
preliminary rt9182 ds9182-05 february 2003 www.richtek.com 9 package information dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.035 0.051 a1 -- 0.152 -- 0.006 b 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.102 0.254 0.004 0.010 l 0.356 0.610 0.014 0.024 sot- 26 surface mount package a a1 e b b d c h l
rt9182 preliminary www.richtek.com ds9182-05 february 2003 10 richtek technology corp. headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 richtek technology corp. taipei office (marketing) 8f-1, no. 137, lane 235, paochiao road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)89191466 fax: (8862)89191465 email: marketing@richtek.com
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