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general description the max1722/max1723/max1724 compact, high-efficiency, step-up dc-dc converters are available in tiny, 5-pin tsot packages. they feature an extremely low 1.5a quiescent supply current to ensure the highest possible light-load efficiency. optimized for operation from one to two alkaline or nickel-metal-hydride (nimh) cells, or a single li+ cell, these devices are ideal for applications where extremely low quiescent current and ultra-small size are critical. built-in synchronous rectification significantly improves efficiency and reduces size and cost by eliminating the need for an external schottky diode. all three devices feature a 0.5 n-channel power switch. the max1722/ max1724 also feature proprietary noise-reduction circuitry, which suppresses electromagnetic interference (emi) caused by the inductor in many step-up applications. the family offers different combinations of fixed or adjustable outputs, shutdown, and emi reduction (see selector guide ). applications beneits and features up to 90% efficiency no external diode or fets needed 1.5a quiescent supply current 0.1a logic-controlled shutdown 1% output voltage accuracy fixed output voltage (max1724) or adjustable output voltage (max1722/max1723) up to 150ma output current 0.8v to 5.5v input voltage range 0.91v guaranteed startup (max1722/max1724) internal emi suppression (max1722/max1724) tsot package (0.9mm typ height) dfn package (2mm x 2mm x 0.75mm) 19-1735; rev 4; 5/16 ordering information and selector guide appears at end of data sheet. pagers remote controls remote wireless transmitters personal medical devices digital still cameras single-cell battery- powered devices low-power hand-held instruments mp3 players personal digital assistants (pda) lx out in 0.8v to 5.5v 3.3v atup to 150ma on off batt max1724 shdn gnd 10h out max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn typical operating circuit downloaded from: http:///
out, shdn , batt, lx to gnd ............................... -0.3v to +6v fb to gnd .............................................. -0.3v to (v out + 0.3v) out, lx current ...................................................................... 1a continuous power dissipation (t a = +70c) 5-pin thin sot (derate 2.7mw/c above +70c) ... 219.10mw operating temperature range ........................... -40c to +85c junction temperature ...................................................... +150c storage temperature range ............................ -65c to +150c soldering temperature lead(pb)-free packages .............................................. +260c packages containing lead(pb) ..................................... +240c (v batt = 1.2v, v out = 3.3v (max1722/max1723), v out = v out(nom) (max1724), shdn = out, r l = , t a = 0c to +85c , unless otherwise noted. typical values are at t a = +25c.) (note 1) parameter symbol conditions min typ max units minimum input voltage max1722/max1724 0.8 v operating input voltage v in t a = +25c max1722/max1724 0.91 5.5 v max1723 (note 2) 1.2 5.5 minimum start-up input voltage t a = +25c, r l = 3k? max1722/max1724 0.83 0.91 v max1723 (note 2) 0.87 1.2 output voltage v out max1724e__27 t a = +25c 2.673 2.7 2.727 v t a = 0c to +85c 2.633 2.767 max1724e__30 t a = +25c 2.970 3.0 3.030 t a = 0c to +85c 2.925 3.075 max1724e__33 t a = +25c 3.267 3.3 3.333 t a = 0c to +85c 3.218 3.383 max1724e__50 t a = +25c 4.950 5.0 5.050 t a = 0c to +85c 4.875 5.125 output voltage range v out max1722/max1723 2 5.5 v feedback voltage v fb max1722/max1723 t a = +25c 1.223 1.235 1.247 v t a = 0c to +85c 1.210 1.260 feedback bias current i fb max1722/max1723 t a = +25c 1.5 20 na t a = +85c 2.2 n-channel on-resistance r ds(on) v out forced to 3.3v 0.5 1.0 ? p-channel on-resistance r ds(on) v out forced to 3.3v 1.0 2.0 ? n-channel switch current limit i lim v out forced to 3.3v 400 500 600 ma switch maximum on-time t on 3.5 5 6.5 s synchronous rectiier zero-crossing current v out forced to 3.3v 5 20 35 ma quiescent current into out (notes 3, 4) 1.5 3.6 a shutdown current into out max1723/max1724(notes 3, 4) t a = +25c 0.01 0.5 a t a = +85c 0.1 quiescent current into batt max1722/max1724(note 4) t a = +25c 0.001 0.5 a t a = +85c 0.01 max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 2 absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. electrical characteristics downloaded from: http:///
(v batt = 1.2v, v out = 3.3v (max1722/max1723), v out = v out(nom) (max1724), shdn = out, r l = , t a = -40c to +85c, unless otherwise noted.) (note 1) (v batt = 1.2v, v out = 3.3v (max1722/max1723), v out = v out(nom) (max1724), shdn = out, r l = , t a = 0c to +85c , unless otherwise noted. typical values are at t a = +25c.) (note 1) note 1: limits are 100% production tested at t a = +25c. limits over the operating temperature range are guaranteed by design. note 2: guaranteed with the addition of a schottky mbr0520l external diode between lx and out when using the max1723 with only one cell, and assumes a 0.3v voltage drop across the schottky diode (see figure 3). note 3: supply current is measured with an ammeter between the output and out pin. this current correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. note 4: v out forced to the following conditions to inhibit switching: v out = 1.05 x v out(nom) (max1724), v out = 3.465v (max1722/max1723). parameter symbol conditions min typ max units shutdown current into batt max1724 (note 4) t a = +25c 0.001 0.5 a t a = +85c 0.01 shdn voltage threshold v il max1723/max1724 75 400 mv v ih max1723/max1724 500 800 shdn input bias current max1723/max1724,v shdn = 5.5v t a = +25c 2 100 na t a = +85c 7 parameter symbol conditions min typ max units output voltage v out max1724e__27 2.633 2.767 v max1724e__30 2.925 3.075 max1724e__33 3.218 3.383 max1724e__50 4.875 5.125 output voltage range v out max1722/max1723 2 5.5 v feedback voltage v fb max1722/max1723 1.200 1.270 v n-channel on-resistance r ds(on) v out forced to 3.3v 1.0 ? p-channel on-resistance r ds(on) v out forced to 3.3v 2.0 ? n-channel switch current limit i lim v out forced to 3.3v 400 620 ma switch maximum on-time t on 3.5 6.5 s synchronous rectiier zero-crossing current v out forced to 3.3v 5 35 ma quiescent current into out (notes 3,4) 3.6 a shdn voltage threshold v il max1723/max1724 75 mv v ih max1723/max1724 800 max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 3 electrical characteristics electrical characteristics (continued) downloaded from: http:///
(figure 3 (max1723), figure 7 (max1722), figure 8 (max1724), v batt = v in = 1.5v, l = 10h, c in = 10f, c out = 10f, t a = +25c, unless otherwise noted.) 100 0.01 0.1 1 10 100 1000 efficiency vs. load current (v out = 3.3v) max1722 toc02 load current (ma) efficiency (%) 60 8050 70 90 v in = 2.0v v in = 2.5v v in = 1.5v v in = 1.0v l = do1606 100 0.01 0.1 1 10 100 1000 efficiency vs. load current (v out = 2.5v) max1722 toc03 load current (ma) efficiency (%) 60 8050 70 90 v in = 1.5v v in = 2.0v v in = 1.0v l = do1606 0 40 120 80 160 200 0 2 1 3 4 5 maximum output current vs. input voltage max1722 toc04 input voltage (v) i out(max) (ma) v out = 2.5v v out = 5.0v v out = 3.3v 10 100 0.8 1.0 1.2 1.4 1.6 2.01.8 2.2 2.4 0.01 0.1 1 startup voltage vs. load current max1722 toc05 load current (ma) startup voltage (v) 0.6 resistive loadv out = 5.0v 0 0.40.2 0.80.6 1.21.0 1.4 1.81.6 2.0 1.0 2.0 2.5 3.0 1.5 3.5 4.0 4.5 5.0 5.5 max1722 toc06 quiescent current (a) output voltage (v) quiescent current into out vs. output voltage no load 0 0.40.2 0.80.6 1.0 1.2 -40 85 startup voltage vs. temperature max1722 toc07 temperature (c) startup voltage (v) 10 -15 35 60 no load 100 0.01 0.1 1 10 100 1000 efficiency vs. load current (v out = 5.0v) max1722 toc01 load current (ma) efficiency (%) 60 8050 70 90 v in = 2.0v v in = 3.3v v in = 4.0v v in = 1.5v v in = 1.0v l = do1606 1s/div i lx 500ma/divv out 50mv/div v lx 2v/div switching waveforms max1722 toc08 i out = 50ma, v out = 5.0v, v in = 3.3v max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn maxim integrated 4 www.maximintegrated.com typical operating characteristics downloaded from: http:///
(figure 3 (max1723), figure 7 (max1722), figure 8 (max1724), v batt = v in = 1.5v, l = 10h, c in = 10f, c out = 10f, t a = +25c, unless otherwise noted.) 200s/div a a: v out , 50mv/div b: i out , 20ma/div b load-transient response max1722 toc09 3.3v 50ma 0 1ms/div v shdn 1v/div 5v 00 2v shutdown response max1722 toc10 v in = 3.3v, v out = 5.0v, r out = 100 ? v out 2v/div 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 -40 -15 10 35 60 85 shutdown input threshold vs. temperature max1722 toc11 temperature (c) shutdown threshold (mv) rising edge falling edge max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn maxim integrated 5 www.maximintegrated.com typical operating characteristics (continued) downloaded from: http:///
max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 6 pin name function tsot udfn max1722 max1723 max1724 max1722 max1723 max1724 1 1 2 2 batt battery input and damping switch connection 1 3 2 1 shdn shutdown input. drive high for normal operation. drive low for shutdown. 2 2 2 3 3 3 gnd ground 3 3 1 1 fb feedback input to set output voltage. use a resistor-divider network to adjust the output voltage. see setting the output voltage section. 4 4 4 6 6 6 out power output. out also provides bootstrap power to the ic. 5 5 5 4 4 4 lx internal n-channel mosfet switch drain and p-channel synchronous rectiier drain 5 5 5 n.c. no connect. pin description pin conigurations top view gnd out 1 5 lx batt max1724 tsot 2 3 4 shdn gnd out fb 1 5 lx shdn tsot 2 3 4 max1723 gnd out fb 1 + 5 lx batt max1722 tsot 2 3 4 4 5 6 3 12 fb batt gnd outn.c. lx max1722 dfn 4 5 6 3 12 shdn batt gnd outn.c. lx max1724 dfn 4 5 6 3 12 fb shdn gnd outn.c. lx max1723 dfn downloaded from: http:///
detailed description the max1722/max1723/max1724 compact, high-effi - ciency, step-up dc-dc converters are guaranteed to start up with voltages as low as 0.91v and operate with an input voltage down to 0.8v. consuming only 1.5a of quiescent current, these devices include a built-in syn - chronous rectifier that reduces cost by eliminating the need for an external diode and improves overall efficiency by minimizing losses in the circuit (see synchronous rectification section). the max1722/max1724 feature a clamp circuit that reduces emi due to inductor ringing. the max1723/max1724 feature an active-low shutdown that reduces quiescent supply current to 0.1a. the max1722/max1723 have an adjustable output voltage, while the max1724 is available with four fixed-output voltage options (see selector guide ). figure 1 is the max1723 simplified functional diagram and figure 2 is the max1724 simplified functional diagram. pfm control scheme a forced discontinuous, current-limited, pulse-frequency - modulation (pfm) control scheme is a key feature of the max1722/max1723/max1724. this scheme provides ultra-low quiescent current and high efficiency over a wide output current range. there is no oscillator; the inductor current is limited by the 0.5a n-channel current limit or by the 5s switch maximum on-time. following each on cycle, the inductor current must ramp to zero before another cycle may start. when the error compara - tor senses that the output has fallen below the regulation threshold, another cycle begins. synchronous rectiication the internal synchronous rectifier eliminates the need for an external schottky diode, thus reducing cost and board space. while the inductor discharges, the p-channel mosfet turns on and shunts the mosfet body diode. as a result, the rectifier voltage drop is significantly reduced, improving efficiency without the addition of external components. low-voltage startup circuit the max1722/max1723/max1724 contain a low-volt - age startup circuit to control dc-dc operation until the output voltage exceeds 1.5v (typ). the minimum start- figure 1. max1723 simplified functional diagram pn control logic startup circuitry driver gnd fb out lx current limit 1.235v reference errorcomparator zero- crossing detector max1723 shdn max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 7 downloaded from: http:///
up voltage is a function of load current (see typical operating characteristics ). this circuit is powered from the batt pin for the max1722/max1724, guaranteeing startup at input voltages as low as 0.91v. the max1723 lacks a batt pin; therefore, this circuit is powered through the out pin. adding a schottky diode in parallel with the p-channel synchronous rectifier allows for startup voltages as low as 1.2v for the max1723 (figure 3). the external schottky diode is not needed for input voltages greater than 1.8v. once started, the output maintains the load as the battery voltage decreases below the startup voltage.shutdown (max1723/max1724) the max1723/max1724 enter shutdown when the shdn pin is driven low. during shutdown, the body diode of the p-channel mosfet allows current to flow from the bat - tery to the output. v out falls to approximately v in - 0.6v and lx remains high impedance. shutdown can be pulled as high as 6v, regardless of the voltage at batt or out. for normal operation, connect shdn to the input. figure 2. max1724 simplified functional diagram figure 3. max1723 single-cell operation pn control logic startup circuitry damping switch driver gnd shdn r 1 r 2 batt lx out current limit max1724 errorcomparator zero- crossing detector 1.235v reference v out = 3.6v 1.2v to v out d1 10 h 10f r22.37m ? r11.24m ? 10f lx out shdn gnd fb max1723 max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 8 downloaded from: http:///
batt/damping switch (max1722/max1724) the max1722/max1724 include an internal damping switch (figure 4) to minimize ringing at lx and reduce emi. when the energy in the inductor is insufficient to supply current to the output, the capacitance and induc - tance at lx form a resonant circuit that causes ringing. the damping switch supplies a path to quickly dissipate this energy, suppressing the ringing at lx. this does not reduce the output ripple, but does reduce emi with minimal impact on efficiency. figures 5 and 6 show the lx node voltage waveform without and with the damping switch, respectively. design procedure setting the output voltage (max1722/max1723) the output voltage can be adjusted from 2v to 5.5v using external resistors r1 and r2 (figure 7). since fb leakage is 20na (max), select feedback resistor r1 in the 100k to 1m range. calculate r2 as follows: out fb v r 2 r 1 1 v ?? = ? ?? ?? where v fb = 1.235v. figure 4. simplified diagram of damping switch figure 5. lx ringing without damping switch (max1723) figure 6. lx ringing with damping switch (max1722/max1724) max1722max1724 pdrv damp ndrv timing circuit out v out v in batt lx dampingswitch gnd p n 1s/div 1v/div 1s/div 1v/div max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 9 downloaded from: http:///
inductor selectionthe control scheme of the max1722/max1723/max1724 permits flexibility in choosing an inductor. a 10h induc - tor value performs well in most applications. smaller inductance values typically offer smaller physical size for a given series resistance, allowing the smallest overall circuit dimensions. circuits using larger inductance val - ues may start up at lower battery voltages, provide higher efficiency, and exhibit less ripple, but they may reduce the maximum output current. this occurs when the induc - tance is sufficiently large to prevent the maximum current limit (i lim ) from being reached before the maximum on- time (t on(max) ) expires. for maximum output current, choose the inductor value so that the controller reaches the current-limit before the maximum on-time is triggered: batt on(max) lim vt l i < where the maximum on-time is typically 5s, and the current limit (i lim ) is typically 500ma (see electrical characteristics table). for larger inductor values, determine the peak inductor current (i peak ) by: batt on(max) peak vt i l = the inductors incremental saturation current rating should be greater than the peak switching current. however, it is generally acceptable to bias the inductor into saturation by as much as 20%, although this will slightly reduce efficiency. table 1 lists suggested inductors and suppliers. maximum output current the maximum output current depends on the peak induc - tor current, the input voltage, the output voltage, and the overall efficiency (): ( ) batt peak out max out v 1 ii 2v ?? = ?? ?? figure 7. adjustable output circuit figure 8. max1724 standard application circuit table 1. suggested inductors and suppliers manufacturer inductor phone website coilcraft do1608 seriesdo1606 series 847-639-2361 www.coilcraft.com murata lqh4c series 770-436-1300 www.murata.com sumida cdrh4d18 series cr32 series cmd4d06 series 847-545-6700 www.sumida.com sumitomo/daidoo electronics cxld140 series +81 (06) 6355-5733 www.daidoo.co.jp toko 3df type d412f type 847-297-0070 www.toko.com max1722 gnd batt output 2v to 5.5v input 0.8v to v out 10h lx out fb r2 10f r1 10f max1724 gnd batt output v out (nom) input 0.8v to v out 10h c210f shdn lx out c1 10f off on max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 10 downloaded from: http:///
for most applications, the peak inductor current equals the current limit. however, for applications using large inductor values or low input voltages, the maximum ontime limits the peak inductor current (see inductor selection section). capacitor selection choose input and output capacitors to supply the input and output peak currents with acceptable voltage ripple. the input filter capacitor (c in ) reduces peak currents drawn from the battery and improves efficiency. low equivalent series resistance (esr) capacitors are recom - mended. ceramic capacitors have the lowest esr, but low esr tantalum or polymer capacitors offer a good bal - ance between cost and performance. output voltage ripple has two components: variations in the charge stored in the output capacitor with each lx pulse, and the voltage drop across the capacitors esr caused by the current into and out of the capacitor: ( ) ( ) ( ) ( ) ( ) ( ) ( ) 22 ripple ripple c ripple esr peak ripple esr esr cout ripple c peak out out batt out vv v v i r 1l v i -i 2 v -v c = + ?? ???? ?? where i peak is the peak inductor current (see inductor selection section). for ceramic capacitors, the output voltage ripple is typically dominated by v ripple(c) . for example, a 10f ceramic capacitor and a 10h inductor typically provide 75mv of output ripple when stepping up from 3.3v to 5v at 50ma. low input-to-output voltage differences (i.e. two cells to 3.3v) require higher output capacitor values. capacitance and esr variation of temperature should be considered for best performance in applications with wide operating temperature ranges. table 2 lists suggested capacitors and suppliers. pc board layout considerations careful pc board layout is important for minimizing ground bounce and noise. keep the ics gnd pin and the ground leads of the input and output capacitors less than 0.2in (5mm) apart using a ground plane. in addition, keep all connections to fb (max1722/max1723 only) and lx as short as possible. table 2. suggested surface-mount capacitors and manufacturers (c1 and c2) manufacturer capacitor value description phone website avx 1f to 10f x7r ceramic 843-448-9411 www.avxcorp.com 10f to 330f taj tantalum series tps tantalum series kemet 1f to 22f x5r/x7r ceramic 864-963-6300 www.kemet.com 10f to 330f t494 tantalum series 68f to 330f t520 tantalum series sanyo 33f to 330f tpc polymer series 408-749-9714 www.secc.co.jp taiyo yuden 33f to 330f x5r/x7r ceramic 800-368-2496 www.t-yuden.org tdk 1f to 10f x7r ceramic 847-803-6100 www.tdk.com vishay sprague 10f to 330f 594d tantalum series 595d tantalum series 203-452-5664 www.vishay.com max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 11 downloaded from: http:///
+ denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. part output (v) shdn lx damping max1722ezk adjustable no yes max1723ezk adjustable yes no max1724ezk27 fixed 2.7 yes yes max1724ezk30 fixed 3.0 yes yes max1724ezk33 fixed 3.3 yes yes max1724ezk50 fixed 5.0 yes yes max1722elt adjustable no yes max1723elt adjustable yes no max1724elt27 fixed 2.7 yes yes max1724elt30 fixed 3.0 yes yes max1724elt33 fixed 3.3 yes yes max1724elt50 fixed 5.0 yes yes package type package code outline no. land pattern no. tsot z5+1 21-0113 90-0241 dfn l622+1 21-0164 90-0004 part temp range pin- package top mark max1722 ezk+t -40c to +85c 5 tsot adqf max1723 ezk+t -40c to +85c 5 tsot adqg max1724 ezk27+t -40c to +85c 5 tsot adqh max1724ezk30+t -40c to +85c 5 tsot adqi max1724ezk33+t -40c to +85c 5 tsot adqj max1724ezk50+t -40c to +85c 5 tsot adqk max1722 elt+t -40c to +85c 6 dfn adh max1723 elt+t -40c to +85c 6 dfn adi max1724 elt+t -40c to +85c 6 dfn adj max1724elt27+t -40c to +85c 6 dfn adk max1724elt33+t -40c to +85c 6 dfn adl max1724elt50+t -40c to +85c 6 dfn adm max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn www.maximintegrated.com maxim integrated 12 selector guide package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. ordering information downloaded from: http:///
revision number revision date description pages changed 0 7/01 initial release 1 9/12 added lead-free and tape-and-reel designations and added soldering temperatures 1, 2 2 5/13 corrected package and thermal information in feature , ordering information , absolute maximum ratings , pin coniguration , and package information 1, 2, 11 3 12/15 added 2 x 2 dfn package 1-3, 5, 11 4 5/16 updated pin conigurations diagram and pin description table 6 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max1722/max1723/max1724 1.5a i q , step-up dc-dc converters in tsot and dfn ? 2016 maxim integrated products, inc. 13 revision history for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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