View MAX8561_4717397.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

general description the max8560/MAX8561/max8562 step-down dc-dc converters are optimized for applications that prioritize small size and high efficiency. they utilize a proprietary hysteretic-pwm control scheme that switches with fixed frequency and is adjustable up to 4mhz, allowing cus- tomers to trade efficiency for smaller external compo- nents. output current is guaranteed up to 500ma, while quiescent current is only 40? (typ). internal synchronous rectification greatly improves effi- ciency and eliminates the external schottky diode required in conventional step-down converters. built-in soft-start eliminates inrush current to reduce input capacitor requirements. the MAX8561 features logic- controlled output voltage, while the max8562 drives an external bypass fet. the max8560 is available in a 5-pin thin sot23 pack- age. the MAX8561/max8562 are available in space- saving 8-pin 3mm x 3mm thin dfn packages. applications microprocessor/dsp core supplies cellular and smart phones cdma/rf power-amplifier supplies pdas, dsc, and mp3 players features ? up to 4mhz pwm switching frequency ? 500ma guaranteed output current ? 40a (typ) quiescent current ? adjustable output voltage from 0.6v to 2.5v ? logic-controlled output voltage (MAX8561) ? drives external bypass fet (max8562) ? 1.5% initial accuracy ? soft-start eliminates inrush current ? fast voltage-positioning transient response ? internal synchronous rectifier ? 2.7v to 5.5v input ? 0.1a logic-controlled shutdown ? thermal shutdown ? thin sot23 or space-saving 3mm x 3mm x 0.8mm tdfn packages max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn ________________________________________________________________ maxim integrated products 1 ordering information gnd in lx fb shdn on/off output 0.6v to 2.5v up to 500ma input 2.7v to 5.5v l 1 h c out 2.2 f c in 2.2 f c ff r1 r2 max8560 t ypical operating circuit 19-2954; rev 1; 1/04 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. evaluation kit available part temp range pin-package top mark max8560 ezk-t -40? to +85? 5 thin sot23-5 adrx MAX8561 eta -40? to +85? 8 tdfn ahd max8562 eta -40? to +85? 8 tdfn ahe gnd fb shdn 15lx in max8560 thin sot23-5 top view 2 34 tdfn 3mm 3mm 0.8mm fb odo odi 1 2 shdn gnd pgnd lx in 3 4 MAX8561/ max8562 8 76 5 pin configurations
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn 2 _______________________________________________________________________________________ absolute maximum ratings stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in, fb, shdn , odi, odo to gnd ............................-0.3v to +6v lx to gnd (note 1)......................................-0.3v to (v in + 0.3v) pgnd to gnd .......................................................-0.3v to +0.3v lx current ...........................................................................1.27a output short circuit to gnd (typical operating circuit)....................................................10s continuous power dissipation (t a = +70?) 5-pin thin sot23 (derate 9.1mw/? above +70?) ....727mw 8-pin tdfn (derate 24.4mw/? above +70?) .........1951mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? electrical characteristics (v in = 3.6v, shdn = in, t a = -40? to +85?, typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units supply voltage range v in 2.7 5.5 v uvlo threshold uvlo v in rising, 60mv hysteresis 2.4 2.5 2.6 v i load = 0ma, no switching 40 80 t a = +25? 0.01 0.1 supply current i in shdn = gnd t a = +85? 0.1 ? output voltage range v out 0.6 2.5 v fb threshold voltage v fb v fb falling 0.6 v fb threshold line regulation v in = 2.7v to 5.5v 0.3 % / v fb threshold load regulation i out = 0 to 500ma -0.001 %/ma t a = +25? -1.5 +1.5 fb threshold voltage accuracy (falling) (% of v fb ) i load = 0ma t a = -40? to +85? -2.5 +2.5 % fb threshold voltage hysteresis (% of v fb ) v hys 1.0 % shdn = gnd, t a = +25?, v in = 5.5v 0.01 0.1 shdn = gnd, t a = +85?, v in = 5.5v 0.1 v fb = 0.5v, t a = +25?, v in = 5.5v 0.01 0.1 fb bias current i fb v fb = 0.5v, t a = +85?, v in = 5.5v 0.1 ? logic input high voltage ( shdn , odi) v ih v in = 2.7v to 5.5v 1.41 logic input low voltage ( shdn , odi) v il v in = 2.7v to 5.5v 0.4 v v in = 5.5v, shdn = odi = gnd or in, t a = +25? 0.001 0.1 logic input bias current i ih , i il v in = 5.5v, shdn = odi = gnd or in, t a = +85? 0.01 ? odo output low voltage (max8562 only) v ol 1ma sink current, v in = 2.7v 0.02 0.1 v note 1: lx has internal clamp diodes to pgnd (gnd for max8560) and in. applications that forward bias these diodes should take care not to exceed the ic? package power-dissipation limits.
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn _______________________________________________________________________________________ 3 electrical characteristics (continued) (v in = 3.6v, shdn = in, t a = -40? to +85?, typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units odo pullup to in (max8562 only) 51020k ? v in = 5.5v, odo = in, t a = +25? 0.01 0.1 open-drain output leakage i ohleak v in = 5.5v, odo = in, t a = +85? 0.1 ? i limp pfet switch 600 990 1500 current limit i limn nfet rectifier 490 680 900 ma r onp pfet switch, i lx = -40ma 0.8 1.5 on-resistance r onn nfet rectifier, i lx = +40ma 0.4 0.82 ? rectifier-off current threshold i lxoff 03060ma v in = 5.5v, lx = gnd to in, odo = in, t a = +25 c, shdn = gnd 0.1 1 lx leakage current i lxlkg v in = 5.5v, lx = gnd to in, odo = in, t a = +85 c, shdn = gnd 1 ? t on ( min ) 107 minimum on- and off-times t off ( min ) 95 ns thermal shutdown +160 c thermal-shutdown hysteresis 20 c t ypical operating characteristics (v in = 3.6v, v out = 1.2v, l = 1? (lqh32cn1r0m53), c out = 2.2?, t a = +25?, unless otherwise noted.) efficiency vs. load current (v out = 2.5v) max8560 toc01 load current (ma) efficiency (%) 100 10 1 50 60 70 80 90 100 40 0.1 1000 4.7 h 2.2 h 1 h efficiency vs. load current (v out = 1.8v) max8560 toc02 load current (ma) efficiency (%) 100 10 1 50 60 70 80 90 100 40 0.1 1000 4.7 h 2.2 h 1 h efficiency vs. load current (v out = 1.5v) max8560 toc03 load current (ma) efficiency (%) 100 10 1 50 60 70 80 90 100 40 0.1 1000 4.7 h 2.2 h 1 h
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn 4 _______________________________________________________________________________________ efficiency vs. load current (v out = 1.2v) max8560 toc04 load current (ma) efficiency (%) 100 10 1 50 60 70 80 90 100 40 0.1 1000 4.7 h 2.2 h 1 h efficiency vs. load current (v out = 0.9v) max8560 toc05 load current (ma) efficiency (%) 100 10 1 50 60 70 80 90 100 40 0.1 1000 4.7 h 2.2 h 1 h efficiency vs. load current (load = 7.5 ? ) max8560 toc06 output voltage (v) efficiency (%) 2.0 1.5 1.0 50 60 70 80 90 100 40 0.5 2.5 4.7 h 2.2 h 1 h no-load supply current vs. supply voltage max8560 toc07 supply voltage (v) supply current ( a) 5.0 4.5 2.5 3.0 3.5 4.0 40 41 42 43 44 45 46 47 39 2.0 5.5 r1 = r2 = 100k ? switching frequency vs. load current max8560 toc08 load current (ma) frequency (mhz) 100 200 300 400 1 10 0.1 0 500 4.7 h 2.2 h 1 h output voltage vs. load current (voltage positioning) max8560 toc09 load current (ma) output voltage (v) 400 300 100 200 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.16 0 500 r1 = r2 = 100k ? light-load switching waveforms max8560 toc10 200ns/div i l 200ma/div v lx 2v/div v out 20mv/div 0 50ma load heavy-load switching waveforms max8560 toc11 200ns/div i l 200ma/div v lx 2v/div v out 20mv/div 0 200ma load t ypical operating characteristics (continued) (v in = 3.6v, v out = 1.2v, l = 1? (lqh32cn1r0m53), c out = 2.2?, t a = +25?, unless otherwise noted.)
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn _______________________________________________________________________________________ 5 heavy-load soft-start waveforms max8560 toc13 20 s/div i l 200ma/div i in 200ma/div v shdn 2v/div v out 1v/div 0 3 ? load line-transient response max8560 toc14 2 s/div i l 200ma/div v in 500mv/div v out 20mv/div 0 5 ? load v in = 4.0v v in = 3.5v load-transient response max8560 toc15 2 s/div i l 500ma/div i load 500ma/div v out 50mv/div 0 20ma load 500ma load 20ma load output-voltage transient response (MAX8561) max8560 toc16 40 s/div i l 200ma/div v odi 2v/div v out 500mv/div 0 7.5 ? load, l = 2.2 h v out = 1.0v v out = 1.5v bypass-fet transient response (max8562) max8560 toc17 20 s/div i l 500ma/div v odi 2v/div v out 2v/div 0 0 7.5 ? load v out = 1.2v v out = v in light-load soft-start waveforms max8560 toc12 20 s/div i l 200ma/div i in 200ma/div v shdn 2v/div v out 1v/div 0 100 ? load t ypical operating characteristics (continued) (v in = 3.6v, v out = 1.2v, l = 1? (lqh32cn1r0m53), c out = 2.2?, t a = +25?, unless otherwise noted.)
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn 6 _______________________________________________________________________________________ detailed description the max8560/MAX8561/max8562 step-down converters deliver a guaranteed 500ma at output levels from 0.6v to 2.5v. they use a proprietary hysteretic-pwm control scheme that switches up to 4mhz, allowing a trade-off between efficiency and tiny external components. at light loads below 100ma, the max8560/MAX8561/max8562 automatically switch to pulse-skipping mode to keep qui- escent supply current as low as 40? (typ). control scheme a proprietary hysteretic-pwm control scheme ensures high efficiency, fast switching, fast transient response, low output ripple, and physically tiny external compo- nents. this control scheme is simple: when the output voltage falls below the regulation threshold, the error comparator begins a switching cycle by turning on the high-side switch. this switch remains on until the mini- mum on-time expires and the output voltage is in regu- lation or the current-limit threshold is exceeded. once off, the high-side switch remains off until the minimum off-time expires and the output voltage falls again, below the regulation threshold. during this period, the low-side synchronous rectifier turns on and remains on until either the high-side switch turns on again or the inductor current approaches zero. the internal syn- chronous rectifier eliminates the need for an external schottky diode. voltage-positioning load regulation as seen in the typical operating circuit , the max8560/MAX8561/max8562 use a unique feedback network. by taking feedback from the lx node through r1, the usual phase lag due to the output capacitor is removed, making the loop exceedingly stable and allowing the use of a very small ceramic output capaci- tor. this configuration causes the output voltage to shift by the inductor series resistance multiplied by the load current. this voltage-positioning load regulation greatly reduces overshoot during load transients, which effec- tively halves the peak-to-peak output-voltage excur- sions compared to traditional step-down converters. see the load transient response graph in the typical operating characteristics section. pin description pin max8560 MAX8561 max8562 name function 11in supply voltage input. 2.7v to 5.5v. bypass with a 2.2? ceramic capacitor as close as possible to the in and gnd pins. 27 gnd ground 38 shdn active-low shutdown input. connect to in or logic high for normal operation. connect to gnd or logic low for shutdown mode. 46fb voltage feedback input. fb regulates to 0.6v nominal. connect fb to the center of an external resistive divider (see the setting the output voltage section). ? pgnd power ground. must connect to gnd. 53 lx inductor connection to the drains of the internal p-channel and n-channel mosfets. ? odo auxiliary open-drain output ? odi digital input for open-drain mosfet. connect to in or logic high to internally pull odo low (and force the max8562 into 100% duty cycle). connect to gnd or logic low to force odo to high impedance (MAX8561) or 10k ? pullup from odo to in (max8562). ? pe p exposed pad. connect to gnd.
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn _______________________________________________________________________________________ 7 shutdown mode connecting shdn to gnd or logic low places the max8560/MAX8561/max8562 in shutdown mode and reduces supply current to 0.1?. in shutdown, the con- trol circuitry, internal-switching p-channel mosfet, and synchronous rectifier (n-channel mosfet) turn off and lx becomes high impedance. connect shdn to in or logic high for normal operation. soft-start the max8560/MAX8561/max8562 have internal soft- start circuitry that eliminates inrush current at startup, reducing transients on the input source. soft-start is par- ticularly useful for higher impedance input sources, such as li+ and alkaline cells. see the soft-start and shutdown response graphs in the typical operating characteristics section. open-drain output the 8-pin tdfn versions, the MAX8561 and max8562, include an extra, internal, open-drain n-channel mosfet switch that can save an additional package in space-con- strained applications. the open drain is connected to odo, while the gate is controlled by a digital input at odi. for the MAX8561, this circuit can be used to toggle between two regulated output voltages, as in figure 2. for the max8562, a 10k ? resistor pulls odo up to in when odi is low, and the buck converter is forced into 100% duty cycle when odi is high. this makes the max8562 ideal for driving an external bypass pfet for high-power mode in cdma cell phones, as in figure 3. applications information the max8560/MAX8561/max8562 are optimized for use with tiny inductors and small ceramic capacitors. the correct selection of external components, especial- ly c ff , ensures high efficiency, low output ripple, and fast transient response. setting the output voltage select an output voltage between 0.6v and 2.5v by connecting fb to a resistive voltage-divider between lx and gnd (see the typical operating circuit ). choose r2 for a reasonable bias current in the resistive divider. a wide range of resistor values is acceptable, but a good starting point is to choose r2 as 100k ? . then, r1 is given by: where v fb = 0.6v. inductor selection the max8560/MAX8561/max8562 operate with inductors of 1? to 4.7?. low inductance values are smaller but require faster switching, which results in some efficiency loss. see the typical operating characteristics section for efficiency and switching frequency vs. inductor value. the inductor? dc current rating only needs to match the maximum load current of the application + 50ma because the max8560/MAX8561/ max8562 feature zero current overshoot during startup and load transients. for output voltages above 2.0v, when light-load efficien- cy is important, the minimum recommended inductor is 2.2?. for optimum voltage-positioning load transients, choose an inductor with dc series resistance in the 50m ? to 150m ? range. for higher efficiency at heavy loads (above 200ma) or minimal load regulation (but some transient overshoot), the resistance should be kept below 100m ? . for light-load applications up to 200ma, much higher resistance is acceptable with very little impact on performance. rr v v out fb 12 1 =? ? ? ? ? ? ? fb lx in 0.6v max8560 MAX8561* max8562* odo *note: odi/odo available in the MAX8561/max8562 only. the MAX8561 odo is an open-drain output. the max8562 has an internal 10k ? pullup to in. **gnd for max8560. odi 10k ? gnd pgnd (gnd)** shdn pwm logic pfet nfet figure 1. simplified functional diagram
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn 8 _______________________________________________________________________________________ capacitor selection output capacitor the output capacitor, c out , is required to keep the output voltage ripple small and to ensure regulation loop stability. c out must have low impedance at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are highly recommended due to their small size, low esr, and small temperature coefficients. due to the unique feedback network, the output capac- itance can be very low. for most applications, a 2.2? capacitor is sufficient. for optimum load-transient per- formance and very low output ripple, the output capaci- tor value in ?s should be equal to or larger than the inductor value in ?s. input capacitor the input capacitor, c in , reduces the current peaks drawn from the battery or input power source and reduces switching noise in the ic. the impedance of c in at the switching frequency should be kept very low. ceramic capacitors with x5r or x7r dielectrics are highly recommended due to their small size, low esr, and small temperature coefficients. due to the max8560/MAX8561/max8562s?soft-start, the input capacitance can be very low. for most applications, a 2.2? capacitor is sufficient. feed-forward capacitor the feed-forward capacitor, c ff , sets the feedback loop response, controls the switching frequency, and is criti- cal in obtaining the best efficiency possible. choose a small ceramic x7r capacitor with a value given by: select the closest standard value to c ff as possible. pc board layout and routing high switching frequencies and relatively large peak cur- rents make the pc board layout a very important part of design. good design minimizes excessive emi on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. connect c in close to in and gnd. connect the inductor and output capacitor as close to the ic as pos- sible and keep their traces short, direct, and wide. connect gnd and pgnd separately to the ground plane. the external feedback network should be very close to the fb pin, within 0.2in (5mm). keep noisy traces, such as the lx node, as short as possible. for the 8-pin tdfn package, connect gnd to the exposed paddle directly under the ic. figure 4 illustrates an example pc board layout and routing scheme. c l r siemens ff = 1 10 gnd in lx fb odo pgnd odi shdn on/off output 1.5v or 1.0v at 500ma input li+ battery 2.2 h 2.2 f 2.2 f 220pf 100k ? 120k ? 150k ? MAX8561 1.5/1.0 figure 2. using odi/odo to obtain two output voltages from the MAX8561 gnd pfet in lx fb odo odi shdn on/off output 1.2v or v batt 1.5 h 2.2 f 2.2 f 150pf 100k ? 100k ? hp = high-power mode lp = low-power mode max8562 input li+ battery hp/lp pgnd figure 3. using the max8562 to control an external bypass pfet for a two-step v cc in cdma-pa applications
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn _______________________________________________________________________________________ 9 manufacturer series inductance (h) esr ( ? ) current rating (ma) dimensions lb2012 1.0 2.2 0.15 0.23 300 240 2.0 x 1.25 x 1.45 = 3.6mm 3 lb2016 1.0 1.5 2.2 3.3 0.09 0.11 0.13 0.20 455 350 315 280 2.0 x 1.6 x 1.8 = 5.8mm 3 lb2518 1.0 1.5 2.2 3.3 0.06 0.07 0.09 0.11 500 400 340 270 2.5 x 1.8 x 2.0 = 9mm 3 taiyo yuden lbc2518 1.0 1.5 2.2 3.3 4.7 0.08 0.11 0.13 0.16 0.20 775 660 600 500 430 2.5 x 1.8 x 2.0 = 9mm 3 lqh31c_03 1.0 0.28 510 3.2 x 1.6 x 2.0 = 10mm 3 lqh32c_53 1.0 2.2 4.7 0.06 0.10 0.15 1000 790 650 3.2 x 2.5 x 1.7 = 14mm 3 murata lqm43fn 2.2 4.7 0.10 0.17 400 300 4.5 x 3.2 x 0.9 = 13mm 3 d310f 1.5 2.2 3.3 0.13 0.17 0.19 1230 1080 1010 3.6 x 3.6 x 1.0 = 13mm 3 toko d312c 1.5 2.2 2.7 3.3 0.10 0.12 0.15 0.17 1290 1140 980 900 3.6 x 3.6 x 1.2 = 16mm 3 sumida cdrh2d11 1.5 2.2 3.3 4.7 0.05 0.08 0.10 0.14 900 780 600 500 3.2 x 3.2 x 1.2 = 12mm 3 table 1. suggested inductors
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn 10 ______________________________________________________________________________________ (b) MAX8561 (c) max8562 (a) max8560 figure 4. recommended pc board layout chip information transistor count: 1271 process: bicmos
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn ______________________________________________________________________________________ 11 package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) thin sot23.eps
max8560/MAX8561/max8562 4mhz, 500ma synchronous step-down dc-dc converters in thin sot and tdfn maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 12 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2004 maxim integrated products printed usa is a registered trademark of maxim integrated products. 6, 8, &10l, dfn thin.eps proprietary information title: approval document control no. rev. 2 1 package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm 21-0137 d l c l c semiconductor dallas a2 a pin 1 index area d e a1 d2 b e2 [(n/2)-1] x e ref. e k 1 n 1 l e l a l pin 1 id c0.35 detail a e number of leads shown are for reference only document control no. approval title: proprietary information rev. 2 2 common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code 6 n t633-1 1.500.10 d2 2.300.10 e2 0.95 bsc e mo229 / weea jedec spec 0.400.05 b 1.90 ref [(n/2)-1] x e 1.500.10 mo229 / weec 1.95 ref 0.300.05 0.65 bsc 2.300.10 t833-1 8 package variations 21-0137 0.250.05 2.00 ref mo229 / weed-3 0.50 bsc 1.500.10 2.300.10 10 t1033-1 0.25 min. k a2 0.20 ref. d semiconductor dallas package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .)

▲Up To Search▲

Price & Availability of MAX8561

	To Download MAX8561 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .