View ADP1754_7284451.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

1.2 a, low v in , low dropout linear regulator data sheet ADP1754 / adp1755 rev. e document feedback information furnished by analog devices is believed to be accurate and reliable. however, no resp onsibility 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 unde r 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 ? 2008 C 2013 analog devices, inc. all rights reserved. technical support www.analog.com features maximum output current: 1.2 a input voltage range: 1 . 6 v to 3. 6 v low shutdown current: < 2 a very l ow dropout voltage: 1 05 mv @ 1.2 a load initial accuracy: 1% accuracy over line, load, and temperature: 2 % 7 fixed output voltage options with s o ft s tart 0. 75 v to 2.5 v ( ADP1754 ) adjust able output voltage option with soft start 0. 75 v to 3. 3 v ( adp1755 ) high psrr 65 db @ 1 khz 65 db @ 10 khz 54 db @ 100 khz 23 v rms at 0.75 v output stable with small 4.7 f ceramic output capacitor excellent load and line transient response current - limit and thermal overload protection power - good indicator logic - controlled enable reverse current protection applications server c omputers memory c omponents telecom munications equipment network equipment dsp/fpga/ microprocessor s upplies instrumentation equipment/data acquisition systems typical application circuits top view (not to scale) ADP1754 1 2 3 4 vin vin 100k? 4.7f 4.7f v in = 1.8v v out = 1.5v vin en 12 11 10 9 vout vout vout sense 5 6 7 8 pg gnd ss nc pg 16 15 14 13 vin vin vout vout 10nf 07722-001 figure 1 . ADP1754 with fixed output volta ge, 1.5 v top view (not to scale) adp1755 1 2 3 4 vin vin 100k? 4.7f 4.7f v in = 1.8v v out = 0.5v(1 + r1/r2) vin en 12 11 10 9 vout vout vout adj 5 6 7 8 pg gnd ss nc pg 16 15 14 13 vin vin vout vout 10nf r2 r1 07722-002 figure 2 . adp1755 with adjustable output voltage, 0.75 v to 3.3 v general description the ADP1754/adp1755 are low dropout (ldo) cmos linear regulators that operate from 1.6 v to 3.6 v and provide up to 1.2 a of outpu t current. these l ow v in / v out ldos are ideal for regulation of nanometer fpga geometries operating from 2.5 v down to 1.8 v i/o rails, and for powering core voltages down to 0.75 v. using an advanced proprietary architecture, the ADP1754/ adp1755 provide h igh power supply rejection ratio (psrr) and low noise, and achieve excellent line and load transient response with only a small 4.7 f ceramic output capacitor. the ADP1754 is available in seven fixed output voltage options. the adp1755 is the adjustable v ersion, which allows output voltages that range from 0.75 v to 3. 3 v via an external divider. the ADP1754/adp1755 allow an external soft start capacitor to be connec ted to program the start up. a digital power - good output allows power system monitors to che ck the health of the output voltage. the ADP1754/adp1755 are available in a 16 - lead, 4 mm 4 mm lfcsp, making them not only very compact solutions, but also providing excellent thermal performance for applications that require up to 1.2 a of output curre nt in a small, low profile footprint.
ADP1754/adp1755 data sheet rev. e | 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 soft start function (ADP1754/adp1755) ............................. 11 adjustable output voltage (adp1755) ................................... 12 enable feature ............................................................................ 12 power - good feature .................................................................. 12 reverse current protection feature ........................................ 13 applications information .............................................................. 14 capacitor selection .................................................................... 14 undervoltage lockout ............................................................... 15 current - limit and thermal overload protection ................. 15 thermal considerations ............................................................ 15 pcb layout considerations ...................................................... 18 outline dimensions ....................................................................... 19 ordering guide .......................................................................... 19 revision his tory 6 /1 3 rev. d to rev. e changed adjustable output voltage option with soft start (adp1755) from 0.75 v to 3. 0 v to 0.75 v to 3. 3 v (throughout) .................................................................................... 1 updated outline dimensions ....................................................... 19 12/12 rev. c to rev. d added junction temperature of 150 c , table 3 ........................... 5 9/12 r ev. b to rev. c changes to absolute maximum ratings, table 3 ......................... 5 changes to ordering guide .......................................................... 19 2/10 rev. a to rev. b changes to table 4 ............................................................................ 5 changes to ordering guide .......................................................... 19 4/09 rev. 0 to rev. a changes to adjustable output voltage accuracy (adp1755) parameter, t able 1 ............................................................................. 3 changes to table 3 ............................................................................. 5 10/08 revision 0: initial version
data sheet ADP1754/adp1755 rev. e | page 3 of 20 specifications v in = (v out + 0. 4 v) or 1.6 v (whichever is greater), i out = 10 ma , c in = c out = 4.7 f , t a = 25c , unless otherwise noted. table 1 . parameter symb ol test conditions /comments 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 = 500 a 90 a i out = 100 ma 4 00 a i out = 100 ma, t j = ? 40c to +125c 800 a i out = 1.2 a 1. 1 ma i out = 1.2 a, t j = ?40c to +125c 1. 4 ma shutdown current i gnd - sd en = gnd , v in = 1.6 v 2 6 a en = gnd, v in = 1. 6 v, t j = ?40c to +85c 30 a en = gnd, v in = 3.6 v, t j = ?40c to +85c 100 a output voltage accuracy fixed output voltage accuracy ( ADP1754 ) v out i out = 10 ma ?1 +1 % i out = 1 0 m a to 1 .2 a ?1.5 +1.5 % 1 0 m a < i out < 1.2 a , t j = ?40c to +125c ?2 +2 % adjustable output voltage accuracy ( adp1755 ) 2 v adj i out = 10 ma 0. 4 9 5 0.5 0. 5 0 5 v i out = 1 0 m a to 1.2 a 0.495 0.505 v 1 0 m a < i out < 1.2 a , t j = ?40c to +125c 0.490 0.510 v line regulation ?v out / ? v in v in = (v out + 0. 4 v) t o 3.6 v, t j = ? 40c to + 125c ? 0. 3 +0. 3 %/v load regulation 3 ?v out / ? i out i out = 10 ma to 1.2 a , t j = ?40c to +125c 0.6 %/ a dropout voltage 4 v dropout i out = 1 00 ma, v out 1.8 v 10 mv i out = 1 0 0 ma, v out 1.8 v, t j = ? 40c to + 125c 16 mv i out = 1.2 a , v out 1.8 v 1 0 5 mv i out = 1.2 a , v out 1.8 v , t j = ? 40c to + 125c 200 mv start - up time 5 t start - up c ss = 0 nf, i out = 10 ma 200 s c ss = 10 nf, i out = 10 ma 5.2 ms current - limit threshold 6 i limit 1.5 2 5 a thermal shutdown thermal shutdown threshold ts sd t j rising 150 c thermal shutdown hysteresis ts sd - hys 15 c pg output logic level pg output logic high pg high 1.6 v v in 3.6 v, i oh < 1 a 1.0 v pg output logic low pg low 1.6 v v in 3.6 v, i ol < 2 ma 0.4 v pg output delay from en transition low to high 1.6 v v in 3.6 v, c ss = 10 nf 5.5 ms pg output threshold output voltage falling pg fal l 1.6 v v in 3.6 v ?10 % output vol tage rising pg rise 1.6 v v in 3.6 v ? 6.5 % en input en input logic high v ih 1.6 v v in 3.6 v 1.2 v en input logic low v il 1.6 v v in 3.6 v 0.4 v en input leakage current v i- leakage en = vin or gnd 0.1 1 a undervoltage lockout uv lo input voltage rising uvlo rise t j = ?40c to +125c 1.58 v input voltage falling uvlo fal l t j = ?40c to +125c 1. 25 v hysteresis uvlo hys t j = 25c 100 mv soft start current i ss 1.6 v v in 3.6 v 0.6 0.9 1. 2 a adj input bias current (ad p1755) adj i- bias 1.6 v v in 3.6 v , t j = ?40c to +125c 1 0 150 na sense input bias current sns i- bias 1.6 v v in 3.6 v 10 a
ADP1754/adp1755 data sheet rev. e | page 4 of 20 parameter symb ol test conditions /comments min typ max unit output noise out noise 10 hz to 100 khz, v out = 0.75 v 23 v rms 10 hz to 100 khz, v out = 2.5 v 6 5 v rms power su pply rejection ratio psrr v in = v out + 1 v, i out = 10 ma 1 khz, v out = 0.75 v 65 db 1 khz, v out = 2.5 v 56 db 10 khz, v out = 0.75 v 65 db 10 khz, v out = 2.5 v 56 db 100 khz, v out = 0.75 v 54 db 100 khz, v out = 2.5 v 51 db 1 minimum output load current is 500 a . 2 accuracy when v out is connected directly to adj. when v out voltage is set by external feedback resistors, absolute accuracy in adjust mode d epend s on the tolerances of resistors used. 3 based on an end - point calculation using 10 ma and 1.2 a loads. see figure 6 for typical load re gulation performance . 4 dropout voltage is defined as the input to output voltage differe ntial when the input voltage is set to the nominal output voltage. this applies only to output voltages above 1.6 v. 5 start - up time is defined as the time between the rising edge of e n to v out be ing at 95% of its nominal value. 6 current - limit threshold i s defined as the current at which the output voltage drops to 90% of the specified typical value. for example, the current li mit for a 1. 0 v output voltage is defined as the current that causes the output voltage to drop to 90% of 1.0 v , or 0. 9 v. input and output cap acitor, recommended specifications table 2 . parameter symbol test conditions /comments min typ max unit minimum input and output capacitance 1 c min t a = ? 40c to +125c 3.3 f capacitor esr r esr t a = ? 40c to +125c 0 .001 0 .1 ? 1 the m inimum input and output capacitance should be greater than 3.3 f over the full range of operating conditions. the full range of ope rating conditions in the application must be considered during device selection to ensure that the minimum capacitance specification is met. x7r and x 5r type capacitors are recommended; y5v and z5u capacitors are not recommended for use with this ldo.
data sheet ADP1754/adp1755 rev. e | page 5 of 20 absolute maximum ratings table 3. parameter rating vin to gnd ?0.3 v to +4.0 v vout to gnd ?0.3 v to vin en to gnd ?0.3 v to vin ss to gnd ?0.3 v to vin pg to gnd ?0.3 v to +4.0 v sense/adj to gnd ?0.3 v to vin storage temperature range ?65c to +150c junction temperature range ?40c to +125c junction temperature 150c 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; 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 individually only, not in combination. the ADP1754/adp1755 may be damaged if 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 need 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 ). t j is calculated 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 circuit board. refer to jedec jesd51-7 for detailed information about board construction. for more information, see the an-772 application note , a design and manufacturing guide for the lead frame chip scale package (lfcsp) . jb is the junction-to-board thermal characterization parameter with units of c/w. jb of the package is based on modeling and calculation using a 4-layer board. the jesd51-12 document, guidelines for reporting and using electronic package thermal information , states that thermal characterization parameters are not the same as thermal resistances. jb measures the component power flowing through multiple thermal paths rather than through 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 package, factors that make jb more useful in real-world applications. maximum junction temperature (t j ) is calculated from the board temperature (t b ) and the power dissipation (p d ) using the following formula: t j = t b + ( p d jb ) refer to the jedec jesd51-8 and jesd51-12 documents 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 16-lead lfcsp with exposed pad (cp-16-4) 42 25.5 c/w esd caution
ADP1754/adp1755 data sheet rev. e | page 6 of 20 pin configuration s and function descrip tions pin 1 indicator 1 vin 2 vin 3 vin 4 en 11 vout 12 vout 10 vout 9 sense 5 pg 6 gnd 7 ss 8 nc 15 vin 16 vin 14 vout 13 vout top view (not to scale) ADP1754 notes 1. nc = no connect. 2. the exposed pad on the bottom of the lfcsp enhances thermal performance and is electrically connected to gnd inside the package. it is recommended that the exposed pad be connected to the ground plane on the board. 07722-003 pin 1 indicator 1 vin 2 vin 3 vin 4 en 11 vout 12 vout 10 vout 9 adj 5 pg 6 gnd 7 ss 8 nc 15 vin 16 vin 14 vout 13 vout top view (not to scale) adp1755 notes 1. nc = no connect. 2. the exposed pad on the bottom of the lfcsp enhances thermal performance and is electrically connected to gnd inside the package. it is recommended that the exposed pad be connected to the ground plane on the board. 07722-004 figure 3 . ADP1754 pin configuration figure 4 . adp1755 pin configuration table 5 . pin function descriptions ADP1754 pin no. adp1755 pin no. mnemonic description 1, 2, 3, 15, 16 1, 2, 3, 15, 16 v in regulator input supply. bypass v in to gnd with a 4.7 f or greate r capacitor. note that a ll five vin pins must be connected to the source . 4 4 en enable input. drive en high to turn on the regulator; drive it low to turn off the regulator. for automatic startup, connect en to v in. 5 5 pg power good. this open - drain ou tput requires an external pull - up resistor to v in. if the part is in shutdown mode , current - limit mode , thermal shutdown, or if it falls below 90 % of the nominal output voltage , pg immediately transi tions low. 6 6 gnd ground . 7 7 ss soft start. a capacit or connected to this pin determines the soft start time. 8 8 nc not connected . no internal connection . 9 n/a sense sense. this pin m easures the actual output voltage at the load and feeds it to the error amplifier. connect sense as close as possible to the load to minimize the effect of ir drop between the regulator output and the load. n/a 9 adj adjust. a resistor divider from v out to adj sets the output voltage. 10, 11, 12, 13, 14 10, 11, 12, 13, 14 v out regulated output voltage. bypass v out to gnd w ith a 4.7 f or greater capacitor. note that a ll five vout pins must be connected to the load . 17 ( ep ad) 17 ( ep ad) exposed pad dle (epad) the e xposed p ad on the b ottom of the lfcsp p ackage enhances thermal performance and is electrically connected to gnd i nside the package. it is recommended that the exposed pad be c onnect ed to the ground plane on the board .
data sheet ADP1754/adp1755 rev. e | page 7 of 20 typical performance characteristics v in = 1.9 v, v out = 1.5 v, i out = 10 ma , c in = 4.7 f , c out = 4.7 f , t a = 25c, unless otherwise noted . 1.520 1.515 1.510 1.505 1.500 1.495 1.490 1.485 1.480 ?40 ?5 25 85 125 output voltage (v) junction temperature (c) load = 10ma load = 100ma load = 400ma load = 800ma load = 1.2a 07722-005 figur e 5. output voltage vs. junction temperature 1.520 1.515 1.505 1.495 1.510 1.500 1.490 1.485 1.480 10 100 1k 10k output voltage (v) load current (ma) 07722-006 figure 6. output voltage vs. load current 1.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 input voltage (v) load = 10ma load = 100ma load = 400ma load = 800ma load = 1.2a 1.520 1.515 1.510 1.505 1.500 1.495 1.490 1.485 1.480 output voltage (v) 07722-007 figure 7. output voltage vs. input voltage 1200 0 200 400 600 800 1000 ?40 ?5 25 85 125 ground current (a) junction temperature (c) load = 10ma load = 100ma load = 400ma load = 800ma load = 1.2a 07722-008 figure 8. grou nd current vs. junction temperature 1200 1000 800 600 400 200 0 10 100 1k 10k ground current (a) load current (ma) 07722-009 figure 9. ground current vs. load current 1200 1000 800 600 400 200 0 1.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 ground current (a) input voltage (v) load = 400ma load = 800ma load = 10ma load = 100ma load = 1.2a 07722-010 figure 10 . ground current vs. input voltage
ADP1754/adp1755 data sheet rev. e | page 8 of 20 100 90 70 80 60 50 40 30 20 10 0 ?40 85 60 35 10 ?15 shutdown current (a) temperature (c) 1.9v 2.0v 2.4v 2.6v 3.0v 3.6v 07722-011 figure 11 . shutdown current vs. temperature at various input voltages 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 1 10 100 1k 10k load current (ma) dropout voltage (v) 1.6v 2.5v 07722-012 figure 12 . dropout voltage vs. load current , v out = 1.6 v, 2.5 v 2.60 2.45 2.55 2.50 2.40 2.35 2.30 2.25 2.20 2.3 2.5 2.7 2.4 2.6 2.8 output voltage (v) input voltage (v) load = 10ma load = 100ma load = 400ma load = 800ma load = 1.2a 07722-013 figure 13 . output voltage vs. input voltage (in dropout) , v out = 2.5 v 4500 2500 4000 3500 3000 2000 1500 1000 500 0 2.3 2.5 2.7 2.4 2.6 2.8 ground current (a) input voltage (v) load = 10ma load = 100ma load = 400ma load = 800ma load = 1.2a 07722-014 figure 14 . ground current vs. input voltage (in dropout) , v out = 2.5 v ch1 500ma ? b w ch2 50mv b w m10s a ch1 380ma 1 2 t 10.40% t i load 1ma to 1.2a load step, 2.5a/s, 500ma/div v out 50mv/div v in = 3.6v v out = 1.5v 07722-015 figure 15 . load transient response , c in = 4.7 f, c out = 4.7 f ch1 500ma ? b w ch2 20mv b w m10s a ch1 340ma 1 2 t 10.20% t i load 1ma to 1.2a load step, 2.5a/s, 500ma/div v out 20mv/div v in = 3.6v v out = 1.5v 07722-016 figure 16 . load transient response , c in = 22 f, c out = 22 f
data sheet ADP1754/adp1755 rev. e | page 9 of 20 1 2 t ch1 500mv b w ch2 5mv b w m10s a ch4 800mv t 9.60% v in 3v to 3.5v input voltage step, 2v/s v out 5mv/div v out = 1.5v c in = c out = 4.7f 07722-017 figure 17 . line transient response, load current = 1200 ma 70 0 10 20 30 40 50 60 0.0001 0.001 0.01 0.1 1 10 noise (v rms) load current (a) 0.75v 1.5v 2.5v 07722-018 figure 18 . noise vs. load current and output voltage 10 1 0.1 0.01 10 100 1k 10k 100k noise spectral density (v/ hz) frequency (hz) 07081-019 0.75v 1.5v 2.5v figure 19 . noise spectral density vs. output voltage , i load = 10 ma 0 ?100 ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 10 100 1k 10k 100k 1m 10m psrr (db) frequency (hz) 1.2a 800ma 400ma 100ma 10ma 07722-020 figure 20 . power supply rejection ratio vs. frequency, v out = 0.75 v, v in = 1.75 v 10 100 1k 10k 100k 1m 10m psrr (db) frequency (hz) 1.2a 800ma 400ma 100ma 10ma 0 ?100 ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 07722-121 figure 21 . power supply rejection ratio vs. frequency, v out = 1.5 v, v in = 2.5 v 0 ?100 ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 10 100 1k 10k 100k 1m 10m psrr (db) frequency (hz) 1.2a 800ma 400ma 100ma 10ma 07722-122 figure 22 . power supply rejection ratio vs. frequency, v out = 2.5 v, v in = 3.5 v
ADP1754/adp1755 data sheet rev. e | page 10 of 20 0 ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 10 100 1k 10k 100k 1m 10m psrr (db) frequency (hz) 1.5v/1200ma 1.5v/10ma 2.5v/1200ma 2.5v/10ma 0.75v/1200ma 0.75v/10ma 07722-123 figure 23 . power supply rejection ratio vs. frequency and output voltage
data sheet ADP1754/adp1755 rev. e | page 11 of 20 theory of operation the ADP1754 / adp1755 are low dropout linear regulat ors that use an advanced, proprietary architecture to provide high power supply rejection ratio (psrr) and excellent line and load transien t response with only a small 4.7 f ceramic output capacitor. both devices operate from a 1.6 v to 3.6 v input rail a nd provide up to 1.2 a of output current. supply current in shut down mode is typically 2 a. uvlo vout vin sense ss short-circuit and thermal protection r1 0.5v ref r2 shutdown en pg gnd ADP1754 reverse polarity protection pg detect 0.9a 07722-021 figure 24 . ADP1754 internal block diagram uvlo vout vin adj ss short-circuit and thermal protection 0.5v ref shutdown en pg gnd adp1755 reverse polarity protection pg detect 0.9a 07722-022 figure 25 . adp1755 internal block diagram internally, the ADP1754 /a dp1755 consist of a reference, an error amplifier, a feedback voltage divider , and a pmos pass transistor. output current is delivered via the pmos pass transistor , which is controlled by the error amplifier. the error amplifier compares the reference volt age 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 an d increasing the output voltage. if the feedback voltage is higher than the reference voltage, the gate of the pmos device is pulled higher, allowing le ss current to pass and decreasing the output voltage. the ADP1754 is available in seven fixed output voltage options between 0. 75 v and 2.5 v . the ADP1754 a llows for connection of an external soft start capacitor that controls the output voltage ramp during startup. the adp1755 is the adjustable version with an output voltage that can be set to a value between 0. 75 v and 3. 3 v by an external vol tage d ivider . both devices are controlled by an enable pin (en) . soft start function ( ADP1754 / adp1755 ) for applications that require a controlled startup, the ADP1754 / adp1755 provide a programmable soft start function. the p rogrammable soft start is usef ul for reducing inrush current upon startup and for providing voltag e sequencing. to implement soft start, connect a small ceramic capacitor fro m ss to gnd. upon startup, a 0.9 a current source charges this capacitor. the ADP1754 / adp1755 start - up output v oltage is limited by the voltage at ss, providing a smooth ramp - up to the nominal output voltage. the soft start time is calculated as follows: t ss = v ref ( c ss / i ss ) (1) where : t ss is the soft start period. v ref is the 0. 5 v reference voltage . c ss is the soft start capacitance from ss to gnd . i ss is the current sourced from ss ( 0.9 a ). w hen the ADP1754 / adp1755 is disabled (using the en pin ), the soft start capacitor is discharged to gnd through an internal 100 ? resistor. 2.50 0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 0 2 4 6 8 10 voltage (v) time (ms) en 1nf 4.7nf 10nf 07722-023 figure 26 . v out ramp - up with external soft start capacitor
ADP1754/adp1755 data sheet rev. e | page 12 of 20 ch1 2.0v b w ch2 500mv b w m40s a ch1 920mv 1 2 t 9.8% t 07722-024 en v out 500mv/div v out = 1.5v c in = c out = 4.7f figure 27 . v out ramp - up with internal soft start adjust able out put voltage ( adp1755 ) the output voltage of the adp1755 can be set over a 0. 7 5 v to 3. 3 v range. the output voltage is set by connecting a resistive voltage divider from v out to adj. the output voltage i s calcu - lated using the following equation : v out = 0. 5 v (1 + r1 / r2 ) (2) where : r1 is the resistor from v out to adj . r 2 is the resistor from adj to gnd. the max imum bias current into adj is 15 0 na . t herefore, to achieve less than 0.5 % error due to the bias current, use values less than 60 k ? for r2. enable feature the ADP1754 /adp1755 use the en pin to enable and disable the v out pin s under normal operating conditions. as shown in figure 28 , w hen a rising voltage on en crosses the active threshold, v out turns on. whe n a falling voltage on en crosses the inactive threshold, v out turns off . 2 ch1 500mv b w ch2 500mv b w m2.0ms a ch1 1.05v 1 t 29.6% t 07722-025 en v out 500mv/div v out = 1.5v c in = c out = 4.7f figure 28 . typical en pin operation as shown in figure 28 , the en pin has hysteresis built in. this hysteresis prevent s on/off o scillations that can o ccur due to noise on the en pin as it passes through the threshold points. the en pin active/inactive thresholds are derived from the v in voltage. therefore , these thresholds vary with changing input voltage . figure 29 shows typical en active/inactive thresholds when the input voltage varies from 1.6 v to 3. 6 v . 1.1 0.5 0.6 0.7 0.8 0.9 1.0 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 en threshold (v) input voltage (v) en active en inactive 07722-026 figure 29 . typical en pin thresholds vs. input voltage power - g ood feature the ADP1754 / adp1755 provide a power - g ood pin , pg , to indicate the status of the output. this o pen - drain output requires an ex ternal pull - up resistor to v in. if the part is in shutdown mode , current - limit mode , thermal shutdown, or if it falls below 9 0 % of the nominal output voltage, pg imm e - diately tra nsi tions low. during soft star t, the rising threshold of the p ower - good signal is 93.5 % of t he nominal output voltage. the open - drain output is held low when the ADP1754 / adp1755 ha ve s ufficient input voltage to turn on the internal pg transistor. an option al soft start delay can be detected. the pg transistor is terminated via a pull - up resistor to v out or v in . power - good accuracy is 93 .5 % of the nominal regulator output voltage when this voltage is rising, with a 90% trip point when this voltage is fallin g. regulator input voltage brown outs or glitches trigger a p ower n o - g ood if v out falls below 90%. a n ormal power - down triggers a p ower no - g ood when v out drops below 90% .
data sheet ADP1754/adp1755 rev. e | page 13 of 20 2 2 ch1 1.0v b w ch3 1.0v b w ch2 500mv b w m40.0s a ch3 900mv 1 t 50.40% t 07722-027 v in 1v/div v out 500mv/div pg 1v/div v out = 1.5v c in = c out = 4.7f figure 30 . typical pg behavior vs. v out , v in rising (v out = 1.5 v) 2 2 ch1 1.0v b w ch3 1.0v b w ch2 500mv b w m40.0s a ch3 900mv 1 t 50.40% t 07722-028 v in 1v/div v out 500mv/div pg 1v/div v out = 1.5v c in = c out = 4.7f figure 31 . typical pg behavior vs. v out , v in falling (v out = 1.5 v) reverse current prot ection feature the ADP1754/adp1755 have additional circuitry to protect against reverse current flow from vout to vin. for a typic al ldo with a pmos pass device, there is an intrinsic bo dy diode between vin and vout. when v in is greater than v out , this diode is reverse - biased. if v out is greater than v in , the intrinsic diode becomes forw ard - biased and conduct s current from vout to vi n , potentially causing destructive power dissipation. the reverse current protection circuitry detects when v out is greater than v in and reverses the direction of the intr insic diode connec - tion, reverse - biasing the diode. the gate of the pmos pass device is also connected to vout, keeping the device off. figure 32 shows a plot of the reverse current vs. the v out to v in differential. 4000 3500 3000 2500 2000 1500 1000 500 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 reverse current (a) v out ? v in (v) 07722-132 figure 32 . reverse current vs. v out ? v in
ADP1754/adp1755 data sheet rev. e | page 14 of 20 application s information capacitor selection output capacitor the ADP1754 / adp1755 are designed for operation with small, space - saving ceramic capacitors, but they can function with most commonly used capacitors as long as care is taken with the effective series resistance ( esr ) v alue. the esr of the output capaci tor affects the stabi lity of the ldo control loop . a mini - mum of 3.3 f capacitance with an esr of 500 m ? or less is recommended to ensure the stability of the ADP1754 / adp1755 . t ransient response to changes in load current is also a ffected by output capacitance . using a larger value of output capacitance improve s the transient response of the ADP1754 / adp1755 to large changes in load current. figure 33 and figure 34 show the transient responses for o utput c apacitance values of 4.7 f and 22 f , respectively . 1 2 t ch1 500ma b w ch2 50mv b w m1s a ch1 380ma t 11.2% i load 1ma to 1.2a load step, 2.5a/s, 500ma/div v out 50mv/div v in = 3.6v, v out = 1.5v c in = c out = 4.7f 07722-133 figure 33 . output trans ient response, c out = 4.7 f 1 2 t ch1 500ma b w ch2 20mv b w m1s a ch1 340ma t 11.0% i load 1ma to 1.2a load step, 2.5a/s, 500ma/div v out 20mv/div v in = 3.6v, v out = 1.5v c in = c out = 22f 07722-134 figure 34 . output transient response, c out = 22 f input bypass capacitor connecting a 4.7 f capacitor from the v in pin to gnd reduces the circuit sensitivity to printed circuit board (pcb) layout, especially when long input traces or high source impedance are encountered. if output capacitance greater than 4.7 f is required, it is recommended that the input capacitor be increased to match it . input and output capacitor properties any good quality c eramic capacitors can be used with the ADP1754 , as long as they meet the minimum capacitance and maximum esr requirements. ceramic capacitors are manufac - tured with a variety of dielectrics, each with different behavior over temperature and applied voltage . c apacitors must have a dielectric adequate to ensure the minimum capacitance over the necessary temperature range and dc bias conditions . x5r or x7r dielectrics with a voltage rating of 6.3 v or 10 v are recom - mended . y5v and z5u dielectrics are not reco mmended , due to their poor temperature and dc bias characteristics. figure 35 shows the capacitance vs . voltage bias characteristic s of a n 0805 case, 4.7 f , 1 0 v, x5r capacitor. the voltage stability of a capacitor is strongly i nfluenced by the capacitor size and voltage rating. in general, a capacitor in a larger package or with a higher voltage rating exhibit s better stability. the temperature variation of the x5r dielectric is about 15% over the ? 40c to + 85 c temperature ran ge and is not a function of package size or voltage rating. 5 4 3 2 1 0 0 2 4 6 8 10 capacitance (f) voltage bias (v) 07722-031 murata p/n grm219r61a475ke34 figure 35 . capacitance vs . voltage bias characteristics equation 3 can be used to determine the worst - case capacitance , accounting for capacitor variation over temperatu re, component tolerance, and voltage. c eff = c out (1 ? tempco ) (1 ? tol ) ( 3 ) where: c eff is the effective capacitance at the operating voltage. tempco is the worst - case capacitor temperature coefficient. tol is the worst - case component tolerance .
data sheet ADP1754/adp1755 rev. e | page 15 of 20 in this example, the worst - case temperature coefficient (te mpco) 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 out = 4.46 f at 1.8 v, as shown in figure 35. substituting these values in equation 3 yields c e ff = 4.46 f (1 ? 0.15) (1 ? 0.1) = 3.41 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 ADP1754 / a dp1755 , it is imperative that the effects of dc bias, temperature , and toler - ances on the behavior of the capacitors be evaluated for each application. u ndervoltage l ockout the ADP1754 / adp1755 have an internal undervoltage lockout circuit that disables all inputs and the output when the input voltage is less than approximately 1.58 v. this ensures that the adp1755 / adp1755 inputs and the output behave in a predicta - ble manner during power - up. c urren t - l imit and t hermal overload protection the ADP1754 / adp1755 are protected against damage due to excessive power dissipation by current - limit and thermal overload protection circuits . the ADP1754 / adp1755 are designed to reach current limit when the output load reaches 2 a (typical). when the output load exceeds 2 a, the output voltage is reduced to maintain a constant current limit. thermal overload protection is included , which limit s the junction temperature to a maximum of 150c (typical) . under extreme conditions (that is, high ambient temperature and power diss ipation) when the junction temperature begins to rise above 150c, the output is turned off , reduc ing the output current to zero . when the junction temperature drops below 135c (typical) , t he output is turned on again and the output current is restored t o its nominal value . consider the case where a hard short from v out to ground occurs. at first , the ADP1754 / adp1755 reach current limit so that only 2 a is conducted into the short. if sel f - heating of the junction becomes great enough to cause its temperat ure to rise above 150c , thermal shutdown activ ate s , turning off the output and reducing the output current to zero. as the junction tempera ture cools and drops below 135c, the output turn s on and conduct s 2 a into the short, again caus ing the junction t emperature to rise above 150c . this thermal oscillation between 135c and 150c cause s a current oscillation between 2 a and 0 a that continue s as long as the short remains at the output. current - limit and thermal overload protections are intended to prote ct the device against accidenta l overload conditions. for reliable operation, device power dissipation should be externally limited so that junction temperatures do not exceed 125c. thermal consideratio ns to guarantee reliable operation, the junction temp erature of the ADP1754/adp1755 must not exceed 125c. to ensure that 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 tem p - erature, power dissipation in the power device, and thermal resistance between the junction and ambient air ( ja ). the ja value is dependent on the package assembly compounds used and the amount of copper to which the gnd pin and the exposed pad (ep ad ) of the package are soldered on the pcb. table 6 shows typical ja values for the 16 - lead lfcsp for various pcb copper sizes. table 7 shows typical jb value s for the 16 - lead lfcsp. table 6 . typical ja values copper size (mm 2 ) ja ( c/w), lfcsp 0 1 130 100 80 500 69 1000 54 6400 42 1 device soldered to minimum size pin traces. table 7 . typical jb values copper size (mm 2 ) jb (c/w) @ 1 w 100 32.7 500 31.5 1000 25.5 the junction temperature of the adp17 54 /adp17 55 can be calculated from the following equation: t j = t a + ( p d ja ) (4) 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 ) (5) where: v in and v out are the input and output voltages, respectively. i load is the load current. i gnd is the ground current. power dissipation due to ground current is quite small and can be ignored. therefore, the junction temperature equat ion can be simplified as follows: t j = t a + {[( v in ? v out ) i load ] ja } (6) as shown in equation 6, for a given ambient temperature, input - to - output voltage differential, and continuous load current, a minimum copper size requirement exists for the pcb to ensure that the junction temperature does not r ise above 125c. figure 36 through figure 41 show junction temperature calculations for different ambient temperatures, load currents, v in to v out differentials, and areas of pcb copper.
ADP1754/adp1755 data sheet rev. e | page 16 of 20 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-032 figure 36. 6400 mm 2 of pcb copper, t a = 25c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-033 figure 37. 500 mm 2 of pcb copper, t a = 25c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-034 figure 38. 0 mm 2 of pcb copper, t a = 25c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 200ma load = 400ma load = 800ma load = 1.2a load = 100ma 07722-035 figure 39. 6400 mm 2 of pcb copper, t a = 50c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-036 figure 40. 500 mm 2 of pcb copper, t a = 50c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-037 figure 41. 0 mm 2 of pcb copper, t a = 50c, lfcsp in cases where the board temperature is known, the thermal characterization parameter, jb , can be used to estimate the junction temperature rise. 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 ) (7)
data sheet ADP1754/adp1755 rev. e | page 17 of 20 figure 42 through figure 45 show junction temperature calcula- tions for different board temperatures, load currents, v in to v out differentials, and areas of pcb copper. 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-038 figure 42. 500 mm 2 of pcb copper, t b = 25c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 100ma load = 200ma load = 400ma load = 800ma load = 1.2a 07722-039 figure 43. 500 mm 2 of pcb copper, t b = 50c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 200ma load = 400ma load = 800ma load = 1.2a load = 100ma 07722-040 figure 44. 1000 mm 2 of pcb copper, t b = 25c, lfcsp 140 120 100 80 60 40 20 0 0.25 0.75 1.25 1.75 2.25 2.75 v in ? v out (v) junction temperature, t j (c) max junction temperature load = 10ma load = 200ma load = 400ma load = 800ma load = 1.2a load = 100ma 07722-041 figure 45. 1000 mm 2 of pcb copper, t b = 50c, lfcsp
ADP1754/adp1755 data sheet rev. e | page 18 of 20 p cb layout consideration s heat dissipation from the package can be improved by increas - ing the amount of copper attached to the pins of the ADP1754 / adp1755 . however, as shown in table 6 , a point of d iminishing ret urns is eventually reached, beyond which an increase in the copper size does not yield significant heat dissipation benefits. here are a few general tips when designing pcbs: ? place the input capacitor as close as possible to the v in and gnd pins. ? place t he output capacitor as close as possible to th e v out and gnd pins. ? p lace the soft start capacitor as c lose as possible to the ss pin. ? connect the load as close as possible to the v out and sense pins (ADP1754) or to the vout and adj pins (adp1755) . use of 0 6 0 3 or 0 8 0 5 size capacitors and resistors achieves the smallest possible footprint solution on boards where area is limited. 07722-044 figure 46 . evaluation board 07722-045 figure 47 . typical board layout top side 07722-046 figure 48 . typical board layout bottom side
data sheet ADP1754/adp1755 rev. e | page 19 of 20 outline dimensions 2 . 2 5 2 . 1 0 s q 1 . 9 5 compliant to jedec standards mo-220-vggc 02-26-2013-b 1 0.65 bsc p i n 1 i n d i c a t o r 1.95 ref 0.75 0.60 0.50 top view 12 max 0.80 max 0.65 typ seating plane coplanarity 0.08 1.00 0.85 0.80 0.35 0.30 0.25 0.05 max 0.02 nom 0.20 ref 16 5 13 8 9 12 4 0.60 max 0.60 max pin 1 indicator 4.10 4.00 sq 3.90 exposed pad for proper connection of the exposed pad, refer to the pin configuration and function descriptions section of this data sheet. 0.25 min bottom view 3.75 bsc sq figure 49. 16-lead lead frame chip scale package [lfcsp_vq] 4 mm 4 mm body, very thin quad (cp-16-4) dimensions shown in millimeters ordering guide model 1 temperature range output voltage (v ) package description package option ADP1754acpz-0.75r7 ?40c to +125c 0.75 16-lead lfcsp_vq cp-16-4 ADP1754acpz-1.0-r7 ?40c to +125c 1.0 16-lead lfcsp_vq cp-16-4 ADP1754acpz-1.1-r7 ?40c to +125c 1.1 16-lead lfcsp_vq cp-16-4 ADP1754acpz-1.2-r7 ?40c to +125c 1.2 16-lead lfcsp_vq cp-16-4 ADP1754acpz-1.5-r7 ?40c to +125c 1.5 16-lead lfcsp_vq cp-16-4 ADP1754acpz-1.8-r7 ?40c to +125c 1.8 16-lead lfcsp_vq cp-16-4 ADP1754acpz-2.5-r7 ?40c to +125c 2.5 16-lead lfcsp_vq cp-16-4 adp1755acpz-r7 ?40c to +125c adjustable from 0.75 to 3.3 16-lead lfcsp_vq cp-16-4 ADP1754-1.5-evalz 1.5 evaluation board adp1755-evalz adjustable evaluation board 1 z = rohs compliant part.
ADP1754/adp1755 data sheet r ev. e | page 20 of 20 ? 2008 C 2013 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d07722 - 0 - 6/13( e) notes

▲Up To Search▲

Price & Availability of ADP1754

	To Download ADP1754 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .