general description the max1852/max1853 monolithic, cmos charge-pump voltage inverters in the ultra-small sc70 package feature a low 15 output resistance, permitting loads up to 30ma with maximum efficiency. the max1852/max1853 are available with operating frequencies of 50khz and 200khz, respectively, allowing optimization of supply current or external component size. small external components and micropower shutdown mode make these devices ideal for both battery-powered and board-level voltage conversion applications. oscillator control circuitry and four power-mosfet switches are included on-chip. applications include generating a negative supply from a +5v or +3.3v logic supply to power analog circuitry. both versions come in a 6-pin sc70 package that is 40% smaller than a sot23. applications negative supply from +5v or +3.3v logic suppliessmall lcd panels gaasfet bias supplies handy-terminals, pdas battery-operated equipment features ? 30ma output current ? low 15 output resistance ? 68a supply current (max1852) ? requires only two 0.68f capacitors (max1853) ? +2.5v to +5.5v input voltage range ? 0.1a logic-controlled shutdown ? two switching frequencies 50khz (max1852)200khz (max1853) ? slew-rate limited to reduce emi ? ultra-small 6-pin sc70 package max1852/max1853 sc70 inverting charge pumps with shutdown ________________________________________________________________ maxim integrated products 1 5 top view gnd c1- in c1+ out sc70-6 1 6 max1852max1853 23 4 shdn pin configuration c1+ c1- in shdn out gnd on 0.68 f 0.68 f off input 2.5v to 5.5v negativeoutput -1 ? v in 30ma max1853 typical operating circuit 19-1792; rev 0; 9/00 ordering information for free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.for small orders, phone 1-800-835-8769. part temp. range pin - pa c k a g e top mark max1852 ext - 40 c to + 85 c 6 sc70 aal max1853 ext - 40 c to + 85 c 6 sc70 aam downloaded from: http:///
max1852/max1853 sc70 inverting charge pumps with shutdown 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics(circuit of figure 1, capacitors from table 2, v in = +5v, shdn = in, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) stresses beyond those listed under ?bsolute 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. in to gnd .................................................................-0.3v to +6v c1+, shdn to gnd .....................................-0.3v to (v in + 0.3v) c1- to gnd...............................................(v out - 0.3v) to +0.3v out to gnd .............................................................+0.3v to -6v out short-circuit to gnd ..............................................1 minute continuous power dissipation (t a = +70?) 6-pin sc70 (derate 3.1mw/? above +70?) .............245mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? note 1: all devices are 100% production tested at t a = +25 c. all temperature limits are guaranteed by design. note 2: output resistance is guaranteed with capacitor esr of 0.3 or less. parameter conditions min typ max units supply voltage range 2.5 5.5 v t a = +25 c 75 130 max1852 t a = -40 c to +85 c 150 t a = +25 c 165 320 quiescent supply current max1853 t a = -40 c to +85 c 350 ? t a = +25 c 0.002 0.5 shutdown supply current shdn = gnd t a = +85 c 0.01 ? t a = +25 c 3 25 06 8 max1852 t a = -40 c to +85 c2 57 8 t a = +25 c 130 200 270 oscillator frequency max1853 t a = -40 c to +85 c 110 310 khz voltage conversion efficiency i out = 0 99 99.9 % t a = +25 c1 5 3 0 output resistance (note 2) i out = 10ma t a = -40 c to +85 c4 0 output current continuous, long-term 30 ma rms shdn input logic high +2.5v v in +5.5v 0.7 v in v shdn input logic low +2.5v v in +5.5v 0.3 v in v t a = +25 c -100 1 100 shdn bias current shdn = gnd or in t a = +85 c1 0 na max1852 260 wake-up time from shutdown i out = 5ma max1853 112 ? downloaded from: http:///
max1852/max1853 sc70 inverting charge pumps with shutdown _______________________________________________________________________________________ 3 12 14 16 18 20 22 24 26 28 -40 -15 10 35 60 85 max1853 output resistance vs. temperature max1852/3 toc09 temperature ( c) output resistance ( ) v in = +3.3v v in = +5v v in = +2.5v 12 14 16 18 20 22 24 26 28 -40 -15 10 35 60 85 max1852 output resistance vs. temperature max1852/3 toc08 temperature ( c) output resistance ( ) v in = +2.5v v in = +5v v in = +3.3v 0 1 2 3 4 5 6 7 8 -40 -15 10 35 60 85 shutdown supply current vs. temperature max1852/3 toc07 temperature ( c) supply current (na) -5.5 -4.5-5.0 -3.5-4.0 -2.5-3.0 -2.0 01 0 1 5 5 202530 max1852 output voltage vs. load current max1852/3 toc01 load current (ma) output voltage (v) v in = +3.3v v in = +5v 0 3020 10 40 50 60 70 80 90 100 01 0 5 15202530 max1853 efficiency vs. load current max1852/3 toc04 load current (ma) efficiency (%) v in = +3.3v v in = +2.5v v in = +5v -5.5 -4.5-5.0 -3.5-4.0 -2.5-3.0 -2.0 01 0 1 5 5 202530 max1853 output voltage vs. load current max1852/3 toc02 load current (ma) output voltage (v) v in = +3.3v v in = +5v 0 3020 10 40 50 60 70 80 90 100 01 0 5 15202530 max1852 efficiency vs. load current max1852/3 toc03 load current (ma) efficiency (%) v in = +5v v in = +2.5v v in = +3.3v 13 1615 14 17 18 19 20 21 22 23 2.5 3.5 3.0 4.0 4.5 5.0 5.5 output resistance vs. input voltage max1852/3 toc05 input voltage (v) output resistance ( ) max1852 max1853 0 4020 100 8060 120 140 180160 200 012345 no-load supply current vs. supply voltage max1852/3 toc06 supply voltage (v) supply current ( a) max1853 max1852 typical operating characteristics (circuit of figure 1, capacitors from table 2, v in = +5v, shdn = in, t a = +25 c, unless otherwise noted.) downloaded from: http:///
max1852/max1853 4 _______________________________________________________________________________________ sc70 inverting charge pumps with shutdown 50 5352 51 5554 5958 57 56 60 -40 -20 0 20 40 60 80 max1852 charge-pump frequency vs. temperature max1852/3 toc10 temperature ( c) frequency (khz) 200 210 205 215 225 220 230 -40 -20 0 20 40 60 80 max1853 charge-pump frequency vs. temperature max1852/3 toc11 temperature ( c) frequency (khz) 20 120 70 170 220 270 2.0 3.5 4.0 2.5 3.0 4.5 5.0 5.5 charge-pump frequency vs. input voltage max1852/3 toc12 input voltage (v) frequency (khz) max1853 max1852 -5.5 -4.5-5.0 -3.5-4.0 -2.5-3.0 -2.0 2.0 3.0 3.5 2.5 4.0 4.5 5.0 5.5 max1852 and max1853 output voltage vs. input voltage max1852/3 toc13 input voltage (v) output voltage (v) i load = 10ma 2 s/div i load = 10ma, ac-coupled max1853 output noise and ripple max1852/3 toc16 v out 20mv/div c1 = c2 = 1 f 0 100 50 200150 300250 350 0.2 2.2 1.2 3.2 4.2 0.7 2.7 1.7 3.7 4.7 output voltage ripple vs. capacitance max1852/3 toc14 capacitance ( f) output voltage ripple (mv) max1853 c1 = c2i load = 10ma max1852 10 s/div i load = 10ma, ac-coupled max1852 output noise and ripple max1852/3 toc15 v out 20mv/div c1 = c2 = 4.7 f 100 s/div max1852 startup from shutdown max1852/3 toc17 shdn 0 0 v out 2v/div 40 s/div max1853 startup from shutdown max1852/3 toc18 shdn 0 0 v out 2v/div typical operating characteristics (continued) (circuit of figure 1, capacitors from table 2, v in = +5v, shdn = in, t a = +25 c, unless otherwise noted.) downloaded from: http:///
detailed description the max1852/max1853 charge pumps invert the volt-age applied to their input. for highest performance use low equivalent series resistance (esr) capacitors (e.g., ceramic). during the first half-cycle, switches s2 and s4 open, switches s1 and s3 close, and capacitor c1 charges to the voltage at in (figure 2). during the second half- cycle, s1 and s3 open, s2 and s4 close, and c1 is level shifted downward by v in volts. this connects c1 in par- allel with the reservoir capacitor c2. if the voltage acrossc2 is smaller than the voltage across c1, charge flows from c1 to c2 until the voltage across c2 reaches -v in . the actual voltage at the output is more positive than -v in since switches s1 s4 have resistance and the load drains charge from c2. efficiency considerations the efficiency of the max1852/max1853 is dominated by their quiescent supply current (i q ) at low output cur- rent and by their output impedance (r out ) at higher output current; it is given by:where the output impedance is roughly approximated by: the first term is the effective resistance of an ideal switched-capacitor circuit (figures 3a and 3b), and r sw is the sum of the charge pump s internal switch resistances (typically 6 at v in = +5v). the typical out- put impedance is more accurately determined from the typical operating characteristics . shutdown the max1852/max1853 have a logic-controlled shut- down input. driving shdn low places the devices in a low-power shutdown mode. the charge-pump switch-ing halts, supply current is reduced to 2na. driving shdn high will restart the charge pump. the switching frequency and capacitor values determine howsoon the device will reach 90% of the input voltage. applications information capacitor selection the charge-pump output resistance is a function of theesr of c1 and c2. to maintain the lowest output resis- tance, use capacitors with low esr. (see table 1 for a list of recommended manufacturers.) tables 2 and 3 suggest capacitor values for minimizing output resis- tance or capacitor size. flying capacitor (c1) increasing the flying capacitor s value reduces the out- put resistance. above a certain point, increasing c1 s capacitance has negligible effect because the outputresistance is then dominated by internal switch resis- tance and capacitor esr. output capacitor (c2) increasing the output capacitor s value reduces the output ripple voltage. decreasing its esr reduces bothoutput resistance and ripple. lower capacitance values can be used with light loads if higher output ripple can be tolerated. use the following equation to calculate the peak-to-peak ripple: r 1 f x c1 2r 4esr esr out osc sw c1 c2 ? () ++ + i ii 1 i x r v out out q out out in ? + ? ?? ? ?? ? max1852/max1853 sc70 inverting charge pumps with shutdown _______________________________________________________________________________________ 5 pin description 6 positive terminal of the flyingcapacitor 1 inverting charge-pump output 2 ground 3 shutdown input. drive this pin highfor normal operation; drive it low for shutdown mode. 4 power-supply voltage input. inputrange is +2.5v to +5.5v. 5 negative terminal of the flyingcapacitor pin function name c1+ out gnd shdn in c1- t e: ( c1 c2 413 on off 5 r l 6 2 c3 c1+ c1- in shdn out gnd input 2.5v to 5.5v negativeoutput -1 ? v in max1852max1853 figure 1. typical application circuit downloaded from: http:///
max1852/max1853 sc70 inverting charge pumps with shutdown 6 _______________________________________________________________________________________ input bypass capacitor (c3) if necessary, bypass the incoming supply to reduce itsac impedance and the impact of the max1852/ max1853s switching noise. a bypass capacitor with a value equal to that of c1 is recommended. voltage inverter the most common application for these devices is acharge-pump voltage inverter (figure 1). this applica- tion requires only two external components capacitors c1 and c2 plus a bypass capacitor, if necessary. refer to the capacitor selection section for suggested capacitor types. cascading devices two devices can be cascaded to produce an evenlarger negative voltage (figure 4). the unloaded output voltage is normally -2 ? v in , but this is reduced slightly by the output resistance of the first device multiplied bythe quiescent current of the second. when cascading more than two devices, the output resistance rises sig- nificantly. for applications requiring larger negative voltages, see the max865 and max868 data sheets. paralleling devices paralleling multiple max1852/max1853s reduces theoutput resistance. each device requires its own pump capacitor (c1), but the reservoir capacitor (c2) serves all devices (figure 5). increase c2 s value by a factor of n , where n is the number of parallel devices. figure 5 shows the equation for calculating output resistance. combined doubler/inverter in the circuit of figure 6, capacitors c1 and c2 form theinverter, while c3 and c4 form the doubler. c1 and c3 are the pump capacitors; c2 and c4 are the reservoir capacitors. because both the inverter and doubler use part of the charge-pump circuit, loading either output causes both outputs to decline toward gnd. make sure the sum of the currents drawn from the two outputs does not exceed 30ma. heavy load connected to a positive supply under heavy loads, where a higher supply is sourcingcurrent into out, the out supply must not be pulled above ground. applications that sink heavy current into out require a schottky diode (1n5817) between gnd and out, with the anode connected to out (figure 7). layout and grounding good layout is important, primarily for good noise per-formance. to ensure good layout, mount all compo- nents as close together as possible, keep traces short to minimize parasitic inductance and capacitance, and use a ground plane. v= i 2(f )c2 2 i esr ripple out osc out c2 + s1 in s2 s3 s4 c1 c2 v out = -(v in ) figure 2. ideal voltage inverter v+ c1 f osc c2 r l v out figure 3a. switched-capacitor model r equiv = r equiv v out r l 1 v+ f osc ? c1 c2 figure 3b. equivalent circuit downloaded from: http:///
max1852/max1853 sc70 inverting charge pumps with shutdown _______________________________________________________________________________________ 7 table 2. capacitor selection to minimize output resistance table 3. capacitor selection to minimize capacitor size table 1. low-esr capacitor manufacturers part frequency (khz) capacitor (f) typical r out ( ) max1852 50 4.7 15 max1853 200 1 15 part frequency (khz) capacitor (f) typical r out ( ) max1852 50 3.3 20 max1853 200 0.68 20 714-960-6492 803-626-3123 603-224-1430 714-960-6492 803-626-3123 fax phone 803-946-0690 714-969-2491 603-224-1961 803-946-0690 714-969-2491 x7r x7r 593d, 595d series 267 series tps series series matsuo avx sprague matsuo avx manufacturer production method surface-mounttantalum surface-mountceramic max1852max1853 4 3 1 v out = (2v in ) - (v fd1 ) - (v fd2 ) c2 +v in c1 52 6 v out = -v in c4 d1 d1, d2 = 1n4148 c3 d2 shdn figure 6. combined doubler and inverter max1852max1853 2 1 gnd out v+ r l figure 7. heavy load connected to a positive supply transistor count: 252 max1852max1853 max1852max1853 4 1 v out c2 4 +v in c1 c1 5 5 226 3 3 6 1 v out = -v in r out = r out of single device number of devices shdn figure 5. paralleling max1852/max1853s to reduce outputresistance chip information max1852max1853 max1852max1853 4 1 v out c2 4 +v in c1 c2 shdn c1 5522 6 33 6 1 v out = -nv in figure 4. cascading max1852/max1853s to increase outputvoltage downloaded from: http:///
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 8 ___________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 (408) 737-7600 2000 maxim integrated products printed usa is a registered trademark of maxim integrated products. max1852/max1853 sc70 inverting charge pumps with shutdown ________________________________________________________package information sc70, 6l.eps downloaded from: http:///
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