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300 ma, low quiescent current, cmos linear regulators adp170/adp171 rev. b information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2009C2010 analog devices, inc. all rights reserved. features maximum output current: 300 ma input voltage range: 1.6 v to 3.6 v low quiescent current i gnd = 23 a with 0 ma load i gnd = 170 a with 300 ma load low shutdown current: <1 a low dropout voltage: 66 mv at 300 ma load output voltage accuracy: 1% up to 31 fixed-output voltage options available from 0.8 v to 3.0 v adjustable-output voltage range 0.8 v to 3.0 v (adp171) accuracy over line, load, and temperature: 3% stable with small 1 f ceramic output capacitor psrr performance of 70 db at 10 khz and 73 db at 1 khz low noise: 30 v rms at v out = 0.8 v current limit and thermal overload protection logic-controlled enable compact 5-lead tsot package applications mobile phones digital camera and audio devices portable and battery-powered equipment dsp/fpga/microprocessor supplies post dc-dc regulation typical application circuits 07716-001 adp170 1 2 3 5 4 v in v out c1 c2 vin gnd en vout nc off on figure 1. adp170 with fi xed output voltage, 1.8 v 07716-002 adp171 1 2 3 5 4 v in = 2.3v v out = 1.8v c in 1f c out 1f vin gnd en vout r1 r2 adj off on figure 2. adp171 with adjustable output voltage general description the adp170/adp171 are low voltage input, low quiescent current, low-dropout (ldo) linear regulators that operate from 1.6 v to 3.6 v and provide up to 300 ma of output current. the low 66 mv dropout voltage at 300 ma load improves efficiency and allows operation over a wide input voltage range. the low 23 a of quiescent current at a 0 ma load makes the adp170/ adp171 ideal for battery-operated portable equipment. the adp170 is capable of 31 fixed-output voltage options, ranging from 0.8 v to 3.0 v. adp171 is an adjustable version, which allows output voltages that range from 0.8 v to 3.0 v via an external divider. the adp170/adp171 are optimized for stable operation with small 1 f ceramic output capacitors. ideal for powering digital processors, the adp170/adp171 exhibit good transient performance and occupy minimal board space. compared with commodity types of ldos, the adp170/adp171 provide 20 db to 40 db better power supply rejection ratio (psrr) at 100 khz, making the adp170/adp171 an ideal power source for analog- to-digital converter (adc) mixed-signal processor systems and allowing use of smaller size bypass capacitors. in addition, low output noise performance without the need for an additional bypass capacitor further reduces printed circuit board (pcb) component count. short-circuit protection and thermal overload protection circuits prevent damage in adverse conditions. the adp170/adp171 are available in tiny 5-lead tsot for the smallest footprint solution to meet a variety of portable power applications.
adp170/adp171 rev. b | page 2 of 20 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 typical application circuits ............................................................ 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 input and output capacitor, recommended specifications ........ 4 absolute maximum ratings ............................................................ 5 thermal data ................................................................................ 5 thermal resistance ...................................................................... 5 esd caution .................................................................................. 5 pin configurations and function descriptions ........................... 6 typical performance characteristics ..............................................7 theory of operation ...................................................................... 11 applications information .............................................................. 12 capacitor selection .................................................................... 12 undervoltage lockout ............................................................... 13 enable feature ............................................................................ 13 current limit and thermal overload protection ................. 14 thermal considerations ............................................................ 14 printed circuit board layout considerations ....................... 16 outline dimensions ....................................................................... 17 ordering guide .......................................................................... 17 revision history 5/10rev. a to rev. b changes to figure 1 and figure 2 ................................................... 1 updated outline dimensions ....................................................... 17 changes to ordering guide .......................................................... 17 6/09rev. 0 to rev. a changes to features section............................................................ 1 updated outline dimensions ....................................................... 17 1/09revision 0: initial version
adp170/adp171 rev. b | page 3 of 20 specifications v in = (v out + 0.4 v) or 1.6 v (whichever is greater), en = v in , i out = 10 ma, c in = c out = 1 f, t a = 25c, unless otherwise noted. table 1. parameter symbol conditions min typ max unit input voltage range v in t j = ?40c to +125c 1.6 3.6 v operating supply current 1 i gnd i out = 0 a 23 a i out = 0 a, t j = ?40c to +125c 60 a i out = 1 ma 50 a i out = 1 ma, t j = ?40c to +125c 100 a i out = 150 ma 130 a i out = 150 ma, t j = ?40c to +125c 210 a i out = 300 ma 170 a i out = 300 ma, t j = ?40c to +125c 260 a shutdown current i gnd-sd en = gnd 0.1 a en = gnd, v in = 3.6 v, t j = ?40c to +85c 2 a en = gnd, v in = 3.6 v, t j = 85c to 125c 25 a fixed-output voltage accuracy v out i out = 10 ma ?1 +1 % 1 ma < i out < 300 ma, v in = (v out + 0.5 v) to 3.6 v ?2 +2 % 1 ma < i out < 300 ma, v in = (v out + 0.5 v) to 3.6 v, t j = ?40c to +125c ?3 +3 % adjustable-output voltage accuracy (adp171) 2 v adj i out = 10 ma 0.495 0.5 0.505 v 1 ma < i out < 300 ma, v in = (v out + 0.5 v) to 3.6 v 0.490 0.510 v 1 ma < i out < 300 ma, v in = (v out + 0.5 v) to 3.6 v, t j = ?40c to +125c 0.485 0.515 v adj input bias current (adp171) adj i-bias 1.6 v v in 3.6 v, adj connected to vout 15 na line regulation ?v out /?v in v in = (v out + 0.5 v) to 3.6 v, t j = ?40c to +125c ?0.25 +0.25 %/v load regulation 3 ?v out /?i out i out = 1 ma to 300 ma 0.001 %/ma i out = 1 ma to 300 ma, t j = ?40c to +125c 0.007 %/ma dropout voltage 4 v dropout i out = 10 ma, v out 1.8 v 2 mv i out = 10 ma, v out 1.8 v, t j = ?40c to +125c 7 mv i out = 150 ma, v out 1.8 v 33 mv i out = 150 ma, v out 1.8 v, t j = ?40c to +125c 70 mv i out = 300 ma, v out 1.8 v 66 mv i out = 300 ma, v out 1.8 v, t j = ?40c to +125c 135 mv start-up time 5 t start-up v out = 1.8 v 120 s current-limit threshold 6 i limit 400 450 800 ma thermal shutdown thermal shutdown threshold ts sd t j rising 150 c thermal shutdown hysteresis ts sd-hys 15 c en input logic high voltage v ih 1.6 v v in 3.6 v 1.2 v logic low voltage v il 1.6 v v in 3.6 v 0.4 v leakage current voltage v i-leakage en = vin or gnd 0.1 a en = vin or gnd, t j = ?40c to +125c 1 a undervoltage lockout uvlo input voltage rising uvlo rise t j = ?40c to +125c 1.5 v input voltage falling uvlo fall t j = ?40c to +125c 0.7 v hysteresis uvlo hys 80 mv
adp170/adp171 rev. b | page 4 of 20 parameter symbol conditions min typ max unit output noise out noise 10 hz to 100 khz, v in = 3.6 v, v out = 3.0 v 72 v rms 10 hz to 100 khz, v in = 3.6 v, v out = 1.8 v 50 v rms 10 hz to 100 khz, v in = 3.6 v, v out = 1.2 v 40 v rms 10 hz to 100 khz, v in = 3.6 v, v out = 0.8 v 30 v rms power supply rejection ratio psrr 1 khz, v in = 3.6 v, i out = 10 ma, v out = 0.8 v 73 db 10 khz, v in = 3.6 v, i out = 10 ma, v out = 0.8 v 70 db 10 khz, v in = (v out + 1 v), i out = 10 ma to 300 ma 50 db 100 khz, v in = (v out + 1 v), i out = 10 ma to 300 ma 47 db 1 the current from the external resistor divider network in the case of adjustable voltage output (as with the adp171) should be subtracted from the ground current measured. 2 accuracy when vout is connected directly to adj. when the vout voltage is set by external feedback resistors, the absolute acc uracy in adjust mode depends on the tolerances of resistors used. 3 based on an en d-point calculation using 1 ma and 300 ma loads. see for typical lo ad regulation perf ormance for loads less than 1 ma. figure 6 4 applies only for output voltages above 1.6 v. dropout voltage is defined as the input-to-output voltage differential when the input voltage is set to the nominal output voltage. 5 start-up time is defined as the time between the rising edge of en and vout being at 90% of its nominal value. 6 current-limit threshold is defined as the current at which the output voltage drops to 90% of the specified typical value. for example, the current limit for a 3.0 v output voltage is defined as the curre nt that causes the output voltage to drop to 90% of 3.0 v, or 2.7 v. input and output capacitor, recommended specifications table 2. parameter symbol conditions min typ max unit minimum input and output capacitance 1 c min t j = ?40c to +125c 0.45 f capacitor esr r esr t j = ?40c to +125c 0.001 1 1 the minimum input and output capacitance should be greater than 0.45 f over the full range of operating conditions. the full range of operating conditions in the application must be considered during devi ce selection to ensure that the minimum capa citance specification is met. x7r and x5r type capacitors are recommended; y5v and z5u capacitors are not recommended for use with any ldo.
adp170/adp171 rev. b | page 5 of 20 absolute maximum ratings table 3. parameter rating vin to gnd ?0.3 v to +3.6 v vout to gnd ?0.3 v to vin en to gnd ?0.3 v to +3.6 v storage temperature range ?65c to +150c operating junction temperature range ?40c to +125c operating ambient temperature range ?40c to +85c soldering conditions jedec j-std-020 stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. thermal data absolute maximum ratings apply only individually, not in combination. the adp170/adp171 can be damaged when the junction temperature limits are exceeded. monitoring ambient temperature does not guarantee that t j is within the specified temperature limits. in applications with high power dissipation and poor thermal resistance, the maximum ambient temperature may have to be derated. in applications with moderate power dissipation and low pcb thermal resistance, the maximum ambient temperature can exceed the maximum limit as long as the junction temperature is within specification limits. the junction temperature (t j ) of the device is dependent on the ambient temperature (t a ), the power dissipation of the device (p d ), and the junction-to- ambient thermal resistance of the package ( ja ). maximum junction temperature (t j ) is calculated from the ambient temperature (t a ) and power dissipation (p d ) using the following formula: t j = t a + ( p d ja ) junction-to-ambient thermal resistance ( ja ) of the package is based on modeling and calculation using a 4-layer board. the junction-to-ambient thermal resistance is highly dependent on the application and board layout. in applications where high maximum power dissipation exists, close attention to thermal board design is required. the value of ja may vary, depending on pcb material, layout, and environmental conditions. the specified values of ja are based on a 4-layer, 4 in. 3 in. pcb. refer to jesd 51-7 for detailed information regarding board construction. jb is the junction-to-board thermal characterization parameter with units of c/w. the jb of the package is based on modeling and calculation using a 4-layer board. the guidelines for reporting and using electronic package thermal information: jesd51-12 states that thermal characterization parameters are not the same as thermal resistances. jb measures the component power flowing through multiple thermal paths rather than a single path as in thermal resistance, jb . therefore, jb thermal paths include convection from the top of the package as well as radiation from the packagefactors that make jb more useful in real-world applications. maximum junction temperature (t j ) is calculated from the board temperature (t b ) and power dissipation (p d ) using the formula t j = t b + ( p d jb ) refer to jesd51-8 and jesd51-12 for more detailed information about jb . thermal resistance ja and jb are specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. table 4. thermal resistance package type ja jb unit 5-lead tsot 170 43 c/w esd caution
adp170/adp171 rev. b | page 6 of 20 pin configurations and function descriptions adp170 top view (not to scale) 1 2 3 5 4 07716-003 vin gnd en vout nc nc = no connect adp171 top view (not to scale) figure 3. adp170 5-lead tsot 1 2 3 5 4 07716-004 vin gnd en vout adj figure 4. adp171 5-lead tsot table 5. pin function descriptions pin no. mnemonic description adp170 adp171 1 1 vin regulator input supply. bypass vin to gnd with a 1 f or greater capacitor. 2 2 gnd ground. 3 3 en enable input. drive en high to turn on the regula tor; drive en low to turn off the regulator. for automatic startup, connect en to vin. 4 nc no connect. not connected internally. 4 adj adjust. a resistor divider from vout to adj sets the output voltage. 5 5 vout regulated output voltage. bypass vout to gnd with a 1 f or greater capacitor.
adp170/adp171 rev. b | page 7 of 20 typical performance characteristics v in = 3.6 v, v out = 1.8 v, i out = 10 ma, c in = c out = 1 f, t a = 25c, unless otherwise noted. ?40 junction temperature (c) v out (v) ?5 25 85 125 1.770 1.775 1.780 1.785 1.790 1.795 1.800 1.805 1.810 i load = 100a i load = 1ma i load = 10ma i load = 100ma i load = 200ma i load = 300ma 07716-005 figure 5. output voltage vs. junction temperature 0.1 0.01 1k load current (ma) 1 10 100 v out (v) 1.798 1.799 1.800 1.801 1.802 1.803 1.804 07716-006 figure 6. output volt age vs. load current v in (v) v out (v) 2.3 2.1 2.5 2.7 2.9 3.1 3.3 3.5 1.798 1.799 1.800 1.801 1.802 1.803 1.804 1.805 07716-007 i load = 100a i load = 1ma i load = 10ma i load = 100ma i load = 200ma i load = 300ma figure 7. output voltage vs. input voltage ?40 junction temperature (c) ground current (a) ?5 25 85 125 0 20 40 60 80 100 120 140 160 180 200 07716-008 i load = 10a i load = 100a i load = 10ma i load = 1ma i load = 100ma i load = 300ma figure 8. ground current vs. junction temperature 0.01 1k load current (ma) 0.1 1 10 100 ground current (a) 0 20 40 60 80 100 120 160 140 180 07716-009 figure 9. ground current vs. load current v in (v) 2.3 2.1 2.5 2.7 2.9 3.1 3.3 3.5 0 40 20 60 80 100 120 160 140 180 ground current (a) 07716-010 i load = 10a i load = 100a i load = 1ma i load = 10ma i load = 100ma i load = 300ma figure 10. ground current vs. input voltage
adp170/adp171 rev. b | page 8 of 20 5.0 4.5 0 ?50 ?25 0 25 50 75 100 125 temperature (c) shutdown current (a) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 07716-011 v in =2.1v v in =2.3v v in =2.7v v in = 2.9v v in = 3.2v v in =3.4v v in =3.5v v in =3.6v figure 11. shutdown current vs. temperature at various input voltages 70 60 50 40 30 20 10 0 0.1 1 10 100 1k 07716-012 dropout voltage (mv) load current (ma) t a = 25c figure 12. dropout voltage vs. load current 1.85 1.80 1.75 1.70 1.65 1.60 1.55 1.50 1.55 1.65 1.75 1.85 1.60 1.70 1.80 1.90 v out (v) v in (v) i load = 1ma i load = 10ma i load = 100ma i load = 200ma i load = 300ma 07716-013 figure 13. output voltage vs. input voltage (in dropout) 400 350 300 250 200 150 100 50 0 1.5 1.7 1.6 1.8 1.9 2.0 07716-014 ground current (a) v in (v) i load = 1ma i load = 10ma i load = 100ma i load = 200ma i load = 300ma figure 14. ground current vs. input voltage (in dropout) ? 30 ?40 ?50 ?60 ?70 ?80 ?90 10 100 1k 10k 100k 1m 10m 07716-015 pssr (db) frequency (hz) 300ma 200ma 100ma 10ma 1ma figure 15. power supply reject ion ratio vs. frequency, v out = 0.8 v 10 100 1k 10k 100k 1m 10m 07716-016 pssr (db) frequency (hz) ? 30 ?40 ?50 ?60 ?70 ?80 ?90 300ma 200ma 100ma 10ma 1ma figure 16. power supply reject ion ratio vs. frequency, v out = 1.8 v
adp170/adp171 rev. b | page 9 of 20 10 100 1k 10k 100k 1m 10m 07716-017 pssr (db) frequency (hz) ? 30 ?40 ?50 ?60 ?70 ?80 ?90 300ma 200ma 100ma 10ma 1ma figure 17. power supply reject ion ratio vs. frequency, v out = 3.0 v 10 100 1k 10k 100k 1m 10m 07716-118 pssr (db) frequency (hz) ? 30 ?40 ?50 ?60 ?70 ?80 ?90 3v, 1ma 1.8v, 1ma 0.8v, 1ma 3v, 300ma 1.8v, 300ma 0.8v, 300ma figure 18. power supply rejection ra tio vs. frequency, various output voltages and load currents 0.01 0.1 1 10 10 100 1k 10k 100k v/rt (hz) frequency (hz) 0.8v v in = 3.6v i load = 10ma c out = 1f 1.8v 3.0v 07716-019 figure 19. output noise spectrum 0 10 20 30 40 50 60 70 0.001 0.01 0.1 1 10 100 1000 rms noise (v) load current (ma) 3v 1.8v 0.8v 07716-020 figure 20. rms noise vs. load current and output voltage 07716-121 ch1 200ma ? ch2 50.0mv b w m40.00s a ch1 124ma 1 2 t 160.680s i load v out v in = 3.6v v out = 1.8v 1ma to 300ma load step, 2.5a/s figure 21. load transient response, c in and c out = 1 f 07716-122 ch1 200ma ? ch2 50.0mv b w m40.0s a ch1 204ma 1 2 t 159.800s i load v out v in = 3.6v v out = 1.8v 1ma to 300ma load step, 2.5a/s figure 22. load transient response, c in and c out = 4.7 f
adp170/adp171 rev. b | page 10 of 20 07716-123 ch1 1.00v ch2 10.0mv m10.0s a ch1 2.94v 1 2 t 39.3000% v in v out v out = 1.8v c in = c out = 1f 2.6v to 3.6v input voltage step, 2v/s figure 23. line transient re sponse, load current = 1 ma 07716-124 ch1 1.00v ch2 10.0mv b w m10.0s a ch1 2.94v 1 2 t 39.3000s v out v in 2.6v to 3.6v input voltage step 2v/s v out = 1.8v c in = c out = 1f figure 24. line transient resp onse, load current = 300 ma
adp170/adp171 rev. b | page 11 of 20 theory of operation the adp170/adp171 are low quiescent current, low-dropout linear regulators that operate from 1.6 v to 3.6 v and can provide up to 300 ma of output current. drawing a low 170 a of quies- cent current (typical) at full load makes the adp170/adp171 ideal for battery-operated portable equipment. shutdown current consumption is typically 100 na. optimized for use with small 1 f ceramic capacitors, the adp170/adp171 provide excellent transient performance. short circuit, uvlo and thermal protect 0.5v reference adp170 shutdown vin vout r1 r2 gnd notes 1. r1 and r2 are internal resistors, available on the adp170 only. en 07716-021 figure 25. adp170 internal block diagram short circuit, uvlo and thermal protect 0.5v reference shutdown vin vout gnd en adj 07716-022 adp171 figure 26. adp171 internal block diagram internally, the adp170/adp171 consist of a reference, an error amplifier, a feedback voltage divider, and a pmos pass transistor. output current is delivered via the pmos pass device, which is controlled by the error amplifier. the error amplifier compares the reference voltage with the feedback voltage from the output and amplifies the difference. if the feedback voltage is lower than the reference voltage, the gate of the pmos device is pulled lower, allowing more current to pass and increasing the output voltage. if the feedback voltage is higher than the reference voltage, the gate of the pmos device is pulled higher, allowing less current to pass and decreasing the output voltage. the adjustable adp171 has an output voltage range of 0.8 v to 3.0 v. the output voltage is set by the ratio of two external resistors, as shown in figure 2 . the device servos the output to maintain the voltage at the adj pin at 0.5 v referenced to ground. the current in r1 is then equal to 0.5 v/r2 and the current in r1 is the current in r2 plus the adj pin bias current. the adj pin bias current, 15 na at 25c, flows through r1 into the adj pin. the output voltage can be calculated using the equation: v out = 0.5 v(1 + r1 / r2 ) + (adj i-bias )(r1 ) the value of r1 should be less than 200 k to minimize errors in the output voltage caused by the adj pin bias current. for example, when r1 and r2 each equal 200 k, the output voltage is 1.0 v. the output voltage error introduced by the adj pin bias current is 3 mv or 0.3%, assuming a typical adj pin bias current of 15 na at 25c. note that in shutdown, the output is turned off and the divider current is zero. the adp170/adp171 use the en pin to enable and disable the vout pin under normal operating conditions. when en is high, vout turns on; when en is low, vout turns off. for automatic startup, en can be tied to vin.
adp170/adp171 rev. b | page 12 of 20 applications information capacitor selection output capacitor the adp170/adp171 are designed for operation with small, space-saving ceramic capacitors but will function with most commonly used capacitors as long as care is taken with regard to the effective series resistance (esr) value. the esr of the output capacitor affects the stability of the ldo control loop. a minimum of 1 f capacitance with an esr of 1 or less is recommended to ensure stability of the adp170/adp171. the transient response to changes in load current is also affected by output capacitance. using a larger value of output capacitance improves the transient response of the adp170/adp171 to large changes in load current. figure 27 and figure 28 show the transient responses for output capacitance values of 1 f and 4.7 f, respectively. 07716-125 ch1 200ma ? ch2 50.0mv b w m200ns a ch1 112ma 1 2 t 500.000ns i load v out v out = 1.8v c in = c out = 1f 1ma to 300ma load step, 2.5a/s figure 27. output transient response, c out = 1 f 07716-126 ch1 200ma ? ch2 50.0mv b w m200ns a ch1 108ma 1 2 t 500.000ns i load v out v out = 1.8v c in = c out = 4.7f 1ma to 300ma load step, 2.5a/s figure 28. output transient response, c out = 4.7 f input bypass capacitor connecting a 1 f capacitor from vin to gnd reduces the circuit sensitivity to the printed circuit board (pcb) layout, especially when long input traces or high source impedance are encountered. if greater than 1 f of output capacitance is required, the input capacitor should be increased to match it. input and output capacitor properties any good quality ceramic capacitor can be used with the adp170/adp171, as long as it meets the minimum capacitance and maximum esr requirements. ceramic capacitors are manu- factured with a variety of dielectrics, each with different behavior over temperature and applied voltage. capacitors must have a dielectric adequate to ensure the minimum capacitance over the necessary temperature range and dc bias conditions. a x5r or x7r dielectric with a voltage rating of 6.3 v or 10 v is recommended. the y5v and z5u dielectrics are not recommended, due to their poor temperature and dc bias characteristics. figure 29 depicts the capacitance vs. bias voltage characteristics of a 0402, 1 f, 10 v x5r capacitor. the variance of a capacitor is strongly influenced by the capacitor size and voltage rating. in general, a capacitor in a larger package or higher voltage rating will exhibit less capacitance variance over bias voltage. the temperature variation of the x5r dielectric is about 15% over the ?40c to +85c temperature range and is not a function of package or voltage rating. 1.2 1.0 0.8 0.6 0.4 0.2 0 02468 07716-025 capacitance (f) bias voltage (v) 1 0 figure 29. capacitance vs. bias voltage characteristics use equation 1 to determine the worst-case capacitance accounting for capacitor variation over temperature, component tolerance, and voltage. c eff = c bias (1 ? tempco ) (1 ? tol) (1) where: c bias is the effective capacitance at the operating voltage. tempco is the worst-case capacitor temperature coefficient. tol is the worst-case component tolerance.
adp170/adp171 rev. b | page 13 of 20 in this example, the worst-case temperature coefficient (tempco) over ?40c to +85c is assumed to be 15% for an x5r dielectric. the tolerance of the capacitor (tol) is assumed to be 10%, and c bias is 0.94 f at 1.8 v, as shown in figure 29 . substituting these values in equation 1 yields c eff = 0.94 f (1 ? 0.15) (1 ? 0.1) = 0.719 f therefore, the capacitor chosen in this example meets the minimum capacitance requirement of the ldo over temper- ature and tolerance at the chosen output voltage. to guarantee the performance of the adp170/adp171, it is imperative that the effects of dc bias, temperature, and toler- ances on the behavior of the capacitors are evaluated for each application. undervoltage lockout the adp170/adp171 have an internal undervoltage lockout circuit that disables all inputs and the output when the input voltage is less than approximately 1.2 v. this ensures that the adp170/adp171 inputs and the output behave in a predictable manner during power-up. enable feature the adp170/adp171 use the en pin to enable and disable the vout pin under normal operating conditions. as shown in figure 30 , when a rising voltage on en crosses the active threshold, vout turns on. when a falling voltage on en crosses the inactive threshold, vout turns off. 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 v en v out 07716-230 figure 30. adp170/adp171 typical en pin operation as shown in figure 30 , the en pin has hysteresis built in. this prevents on/off oscillations that can occur due to noise on the en pin as it passes through the threshold points. the en pin active/inactive thresholds are derived from the vin voltage. therefore, these thresholds vary with changing input voltage. figure 31 shows typical en active/inactive thresholds when the input voltage varies from 1.6 v to 3.6 v. 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.50 1.65 1.80 1.95 2.10 2.25 2.40 2.55 2.70 2.85 3.00 3.15 3.30 3.45 3.60 typical en tresholds (v) v in (v) en active en inactive 07716-129 figure 31. typical en pin thresholds vs. input voltage the adp170/adp171 utilize an internal soft start to limit the inrush current when the output is enabled. the start-up time for the 1.8 v option is approximately 120 s from the time the en active threshold is crossed to when the output reaches 90% of its final value. as shown in figure 32 , the start-up time is dependent on the output voltage setting. 07716-130 ch1 1.00v ch2 1.00v b w m20.0s a ch1 2.72v 1 2 t 79.8000s v out = 0.8v v out = 1.8v v out = 3.0v en figure 32. typical start-up time
adp170/adp171 rev. b | page 14 of 20 current limit and thermal overload protection the adp170/adp171 are protected against damage due to excessive power dissipation by current and thermal overload protection circuits. the adp170/adp171 are designed to limit the current when the output load reaches 450 ma (typical). when the output load exceeds 450 ma, the output voltage is reduced to maintain a constant current limit. thermal overload protection is included, which limits the junction temperature to a maximum of 150c (typical). under extreme conditions (that is, high ambient temperature and power dissip- ation), when the junction temperature starts to rise above 150c, the output is turned off, reducing the output current to 0. when the junction temperature drops below 135c, the output is turned on again and output current is restored to its nominal value. consider the case where a hard short from vout to gnd occurs. at first, the adp170/adp171 will limit the current so that only 450 ma is conducted into the short. if self-heating of the junction is great enough to cause its temperature to rise above 150c, thermal shutdown will activate, turning off the output and reducing the output current to 0. as the junction temperature cools and drops below 135c, the output turns on and conducts 450 ma into the short, again causing the junction temperature to rise above 150c. this thermal oscillation between 135c and 150c causes a current oscillation between 450 ma and 0 ma, which continues as long as the short remains at the output. current and thermal limit protections are intended to protect the device against accidental overload conditions. thermal considerations to guarantee reliable operation, the junction temperature of the adp170/adp171 must not exceed 125c. to ensure the junction temperature stays below this maximum value, the user needs to be aware of the parameters that contribute to junction temperature changes. these parameters include ambient temperature, power dissipation in the power device, and thermal resistances between the junction and ambient air ( ja ). the ja number is dependent on the package assembly compounds used and the amount of copper to which the gnd pin of the package is soldered on the pcb. table 6 shows typical ja values of the 5-lead tsot package for various pcb copper sizes. table 6. typical ja values copper size (mm 2 ) ja (c/w) 0 1 170 50 152 100 146 300 134 500 131 1 device soldered to minimum size pin traces. the junction temperature of the adp170/adp171 can be calculated from the following equation: t j = t a + ( p d ja ) (2) where: t a is the ambient temperature. p d is the power dissipation in the die, given by p d = [( v in ? v out ) i load ] + ( v in i gnd ) (3) where: i load is the load current. i gnd is the ground current. v in and v out are input and output voltages, respectively. power dissipation due to ground current is quite small and can be ignored. therefore, the junction temperature equation simplifies to the following: t j = t a + {[( v in ? v out ) i load ] ja } (4) as shown in equation 4, for a given ambient temperature, input to output voltage differential, and continuous load current, there exists a minimum copper size requirement for the pcb to ensure that the junction temperature does not rise above 125c. figure 33 to figure 38 show junction temperature calculations for different ambient temperatures, load currents, v in to v out differentials, and areas of pcb copper. 140 120 100 80 60 40 20 0 0.5 1.0 1.5 2.0 2.5 3.0 07716-028 junction temperature (c) v out ? v in (v) i load = 1ma i load = 10ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max figure 33. 500 mm 2 of pcb copper, t a = 25c 140 120 100 80 60 40 20 0 07716-029 junction temperature (c) v out ? v in (v) i load = 1ma i load = 10ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max 0.5 1.0 1.5 2.0 2.5 3.0 figure 34. 100 mm 2 of pcb copper, t a = 25c
adp170/adp171 rev. b | page 15 of 20 140 120 100 80 60 40 20 0 07716-030 junction temperature (c) v in ? v out (v) i load = 1ma i load = 10ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max 0.5 1.0 1.5 2.0 2.5 3.0 figure 35. 0 mm 2 of pcb copper, t a = 25c 140 120 100 80 60 40 20 0 07716-031 junction temperature (c) v out ? v in (v) i load = 1ma i load = 10ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max 0.5 1.0 1.5 2.0 2.5 3.0 figure 36. 500 mm 2 of pcb copper, t a = 50c 140 120 100 80 60 40 20 0 07716-032 junction temperature (c) v out ? v in (v) i load = 1ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max i load = 10ma 0.5 1.0 1.5 2.0 2.5 3.0 figure 37. 100 mm 2 of pcb copper, t a = 50c 140 120 100 80 60 40 20 0 07716-033 junction temperature (c) v out ? v in (v) i load = 1ma i load = 25ma i load = 100ma i load = 150ma i load = 300ma t j max i load = 10ma 0.5 1.0 1.5 2.0 2.5 3.0 figure 38. 0 mm 2 of pcb copper, t a = 50c in cases where board temperature is known, use the thermal characterization parameter, jb , to estimate the junction tem- perature rise (see figure 39 ). maximum junction temperature (t j ) is calculated from the board temperature (t b ) and power dissipation (p d ) using the following formula: t j = t b + ( p d jb ) (5) the typical value of jb is 42.8c/w for the 5-lead tsot package. 140 120 100 80 60 40 20 0 07716-034 junction temperature (c) v in ? v out (v) i load = 1ma i load = 10ma i load = 50ma i load = 100ma i load = 150ma i load = 250ma i load = 300ma t j max 0.4 0.8 1.2 1.6 2.0 2.4 2.8 figure 39. tsot, t a = 85c
adp170/adp171 rev. b | page 16 of 20 j1 analog devices adp171-x.x-evalz vin vout gnd en gnd c1 c2 gnd gnd u1 r2 r1 07716-036 printed circuit board layout considerations heat dissipation from the package can be improved by increasing the amount of copper attached to the pins of the adp170/adp171. however, as can be seen from table 6 , a point of diminishing returns is eventually reached, beyond which an increase in the copper size does not yield significant heat dissipation benefits. place the input capacitor as close as possible to the vin and gnd pins. place the output capacitor as close as possible to the vout and gnd pins. use of 0402 or 0603 size capacitors and resistors achieves the smallest possible footprint solution on boards where area is limited. j1 analog devices adp170-x.x-evalz vin vout gnd en gnd c1 c2 gnd gnd u1 07716-035 figure 41. example adp171 pcb layout figure 40. example adp170 pcb layout
adp170/adp171 rev. b | page 17 of 20 outline dimensions 100708-a * compliant to jedec standards mo-193-ab with the exception of package height and thickness. 1.60 bsc 2.80 bsc 1.90 bsc 0.95 bsc 0.20 0.08 0.60 0.45 0.30 8 4 0 0.50 0.30 0.10 max * 1.00 max * 0.90 max 0.70 min 2.90 bsc 54 12 3 seating plane figure 42. 5-lead thin small outline transistor package [tsot] (uj-5) dimensions show in millimeters ordering guide model 1 temperature range output voltage (v) 2 package description package option branding adp170aujz-1.2-r7 C40c to +125c 1.2 5-lead tsot uj-5 l8e adp170aujz-1.5-r7 C40c to +125c 1.5 5-lead tsot uj-5 l8f adp170aujz-1.8-r7 C40c to +125c 1.8 5-lead tsot uj-5 l8g adp170aujz-2.5-r7 C40c to +125c 2.5 5-lead tsot uj-5 l8h adp170aujz-2.8-r7 C40c to +125c 2.8 5-lead tsot uj-5 l8p adp171aujz-r7 C40c to +125c 0.8 to 3. 0 (adjustable) 5-lead tsot uj-5 l9a adp170-1.8-evalz evaluation board adp170-bl1-evz evaluation board adp171-evalz evaluation board adp171-bl1-evz evaluation board 1 z = rohs compliant part. 2 for additional voltage options, contact your local analog devices, inc., sales or distribution representative.
adp170/adp171 rev. b | page 18 of 20 notes
adp170/adp171 rev. b | page 19 of 20 notes
adp170/adp171 rev. b | page 20 of 20 notes ?2009C2010 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d07716-0-5/10(b)

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