max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 19-4241; rev 2; 6/15 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maximintegrated.com. general description the max16945 ultra-small, monolithic, cmos charge-pump voltage inverter accepts an input voltage ranging from +1.4v to +5.5v. this device features an ultra-low 12 output resistance, permitting loads of up to 30ma at +105? with maximum efficiency. the max16945operates at a frequency of 125khz, allowing use of small external components. its small external compo- nents, micropower shutdown mode, and wide tempera- ture range make this device ideal for both automotive and industrial applications. oscillator control circuitry and four power mosfet switches are included on-chip. the max16945 comes in a 6-pin sot23 package and operates over -40? to +105?. applications automotive and industrial equipmentsmall lcd panels negative supply from +5v or +3.3v logic supplies gaasfet bias supplies handy-terminals, pdas features ? +1.4v to +5.5v input voltage range ? 30ma guaranteed output current at +105? ? slew-rate limited to reduce emi ? 0.1? logic-controlled shutdown ? low 12 output resistance ? startup current limited ? 6-pin sot23 package ? aec-q100 qualified shdn 5 top view in gnd c1- c1+ out sot23 1 6 max16945 23 4 pin configuration c1+ c1- in shdn out gnd on 1 f 1 f off input 1.5v to 5.5v negativeoutput -1 ? v in 60ma max16945 typical operating circuit # denotes an rohs-compliant device that may include lead that is exempt under rohs requirements. /v denotes an automotive qualified part. + denotes a lead(pb)-free/rohs-compliant package. note: the max16945 requires a special solder temperature profile described in the absolute maximum ratings section. ordering information part temp range pin-package max16945tgut# -40c to +105c 6 sot23 max16945tgut/v+ -40c to +105c 6 sot23 downloaded from: http:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 2 maxim integrated absolute maximum ratings electrical characteristics(circuit of figure 1, c1 = c2 =2.2?, v in = v shdn = +5v, v gnd = 0, t a = 0? to +105? , unless otherwise noted. typical values are at t a = +25?.) 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 output current............................................................90ma out short circuit to gnd..............................................indefinite continuous power dissipation (t a = +70?) 6-pin sot23 (derate 7.4mw/? above +70?) (note 1) .....595mw junction-to-case thermal resistance ( jc ) (note 1) 6-pin sot23 ................................................................39?/w junction-to-ambient thermal resistance ( ja ) (note 1) 6-pin sot23 ..............................................................134?/w operating temperature range .........................-40? to +105? junction temperature. .....................................................+150? storage temperature range ............................-65? to +150? lead temperature.......................................................... (note 2) note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . note 2: this device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board-level solder attach and rework. maxim recommends the use of the solder profiles recom-mended in the industry-standard specification, jedec 020a, paragraph 7.6, table 3 for ir/vpr and convection reflow processes. preheating, per this standard, is required. hand or wave soldering is not recommended. parameter conditions min typ max units t a = +25? 1.4 5.5 supply voltage range r l = 5k t a = 0? to +105? 1.5 5.5 v quiescent supply current t a = +25? (note 3) 950 1700 ? t a = +25? 0.002 1 shutdown supply current v shdn = 0 t a = 0? to +105? 0.03 ? short-circuit current output shorted to ground, t a = +25? 170 ma oscillator frequency t a = +25? 70 125 180 khz voltage conversion efficiency i out = 0, t a = +25? 99 99.9 % t a = +25? 12 25 output resistance i ou t = 30m a ( n ote 4) t a = 0? to +105? 36 out-to-gnd shutdown resistance v shdn = 0, out is internally pulled to gnd in shutdown 3 8.5 2.5v v in 5.5v 2.0 shdn input logic-high v in(min) v in 2.5v v in - 0.2 v 2.5v v in 5.5v 0.6 shdn input logic-low v in(min) v in 2.5v 0.2 v t a = +25? -100 +0.05 +100 shdn bias current shdn = gnd or in t a = 0? to +105? 10 na wake-up time from shutdown i out = 15ma 100 ? downloaded from: http:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 3 maxim integrated electrical characteristics (continued)(circuit of figure 1, c1 = c2 =2.2?, v in = v shdn = +5v, v gnd = 0, t a = 0? to +105? , unless otherwise noted. typical values are at t a = +25?.) note 3: the max16945 may draw high supply current during startup, up to the minimum operating supply voltage. to guaranteeproper startup, the input supply must be capable of delivering 90ma more than the maximum load current. note 4: output resistance is guaranteed with capacitor esr of 0.3 or less. note 5: all specifications from -40? to +105? are guaranteed by design, not production tested. parameter conditions min typ max units supply voltage range r l = 5k 1.6 5.5 v output current continuous, long-term 60 ma rms quiescent supply current (note 3) 1800 ? oscillator frequency 60 125 200 khz output resistance i out = 30ma (note 5) 36 out-to-gnd shutdown resistance v shdn = 0, out is internally pulled to gnd in shutdown 8.5 2.5v v in 5.5v 2.1 shdn input logic-high v in(min) v in 2.5v v in - 0.2 v 2.5v v in 5.5v 0.6 shdn input logic-low v in(min) v in 2.5v 0.2 v typical operating characteristics (circuit of figure 1, c1 = c2 = 2.2?, v in = v shdn = +5v, v gnd = 0, t a = +25?, unless otherwise noted.) -5.0 -3.5-4.0 -4.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0 02 0 10 30 40 50 output voltage vs. output current max16945 toc01 output current (ma) output voltage (v) v in = +2v v in = +3.3v v in = +5v 0 3020 10 40 50 60 70 80 90 100 02 0 10 30 40 50 efficiency vs. output current max16945 toc02 output current (ma) efficiency (%) v in = +5v v in = +3.3v v in = +2v 0 10 5 2015 25 30 35 40 1.5 2.5 3.0 2.0 3.5 4.0 4.5 5.0 5.5 output impedance vs. input voltage max16945 toc03 input voltage (v) output impedance ( ) downloaded from: http:///
30ma inverting charge pump in sot23 for emi-sensitive automotive applications max16945 4 maxim integrated 0 0.5 1.0 1.5 2.0 2.5 1.0 2.5 3.0 1.5 2.0 3.5 4.0 4.5 5.0 5.5 supply current vs. supply voltage max16945 toc04 supply voltage (v) supply current (ma) 110 112111 115114 113 116 117 119118 120 -40 -10 5 -25 203550658095110125 pump frequency vs. temperature max16945 toc07 temperature ( c) pump frequency (khz) 0 200100 400300 600500 700 -40 -10 5 20 -25 3550658095110125 shutdown supply current vs. temperature max16945 toc05 temperature ( c) supply current (na) v in = +5v v in = +3.3v v in = +2v 0 5 3515 10 20 25 30 40 -40 -10 5 20 -25 35 50 95 80 110 65 125 output impedance vs. temperature max16945 toc06 temperature ( c) output impedance ( ) v in = +2v v in = +3.3v v in = +5v 2 s/div output noise and ripple 10mv/div max16945 toc08 40 s/div startup from shutdown v out 2v/div max16945 toc09 shdn5v/div typical operating characteristics (continued) (circuit of figure 1, c1 = c2 = 2.2?, v in = v shdn = +5v, v gnd = 0, t a = +25?, unless otherwise noted.) downloaded from: http:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 5 maxim integrated detailed description the max16945 capacitive charge pump inverts thevoltage applied to its input. for highest performance, use low-esr capacitors. 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 parallel with the reservoir capacitor c2. if the voltageacross c2 is smaller than the voltage across c1, charge flows from c1 to c2 until the voltage across c2 reaches -v in . the absolute value of the inverting output voltage is always smaller than the value of the inputvoltage due to the losses of the flying capacitor c1 and the resistance of the switches s1?4. 0 50 100 150 200 250 04 5 23 1 678910 output ripple vs. capacitance max16945 toc11 capacitance ( f) output ripple (mv) v in = +4.375v, v out = -4v v in = +2.825v, v out = -2.5v v in = +1.7v, v out = -1.5v pin description typical operating characteristics (continued) (circuit of figure 1, c1 = c2 = 2.2?, v in = v shdn = +5v, v gnd = 0, t a = +25?, unless otherwise noted.) c1 c2 215 on off 3 r l 6 4 c3 c1+ c1- in shdn out gnd input 1.5v to 5.5v negativeoutput -1 ? v in max16945 figure 1. typical application circuit 0 3020 10 40 50 60 04 3 12 5678910 output current vs. capacitance max16945 toc10 capacitance ( f) output current (ma) v in = +4.375v, v out = -4v v in = +2.825v, v out = -2.5v v in = +1.7v, v out = -1.5v pin name function 1 out inverting charge-pump output 2 in power-supply voltage input. input range is 1.4v to 5.5v. 3 c1- negative terminal of the flying capacitor 4 gnd ground 5 shdn shutdown input. drive shdn high for normal operation; drive shdn low for shutdown mode. out is actively pulled to ground during shutdown. 6 c1+ positive terminal of the flying capacitor s1 in s2 s3 s4 c1 c2 v out = -(v in ) figure 2. ideal voltage inverter downloaded from: http:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 6 maxim integrated efficiency considerations the efficiency of the max16945 is dominated by its qui-escent supply current (i q ) at low output current, and by its output impedance (r out ) at higher output current. efficiency is calculated as follows: 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? internal switch resistances (typically 4 to 5 at v in = +5v). the typi- cal output impedance is more accurately determinedfrom the typical operating characteristics . current limit the max16945 limits its input current upon startup to170ma (typ). this prevents low-current or higher output impedance input supplies (such as alkaline cells) from being overloaded when power is applied or when the device awakes from shutdown. shutdown the max16945 has a logic-controlled shutdown input.driving shdn low places the device in a low-power shutdown mode. the charge-pump switching halts,supply current is reduced to 2na, and out is actively pulled to ground through a 3 resistance. driving shdn high will restart the charge pump. the switching frequency and capacitor values determinehow soon 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. flying capacitor (c1) increasing the flying capacitor? value reduces the out-put resistance. above a certain point, increasing c1? capacitance has negligible effect because the output resistance is then dominated by internal switch resis- tance and capacitor esr. output capacitor (c2) increasing the output capacitor? value reduces theoutput ripple voltage. decreasing its esr reduces both output 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: input bypass capacitor (c3) if necessary, bypass the incoming supply to reduce itsac impedance and the impact of the max16945? switching noise. an input bypass capacitor (c3) 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 an input bypass capacitor c3, if nec- essary. see the capacitor selection section for sug- gested capacitor sizes. v= i 2(f )c2 2 i esr ripple out osc out c2 + 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 ? + ? ? ? ? ? ? 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:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 7 maxim integrated cascading devices two devices can be cascaded to produce an even largernegative voltage (figure 4). the unloaded output voltage is normally -2 x v in , but this is reduced slightly by the out- put resistance of the first device when multiplied by the quiescent current of the second. when cascading more than two devices, the output resistance rises dramati- cally. the maximum load current and startup current of the nth cascaded circuit must not exceed the maximum output current capability of the (n-1)th circuit to ensure proper startup. paralleling devices paralleling multiple max16945s reduces the outputresistance. each device requires its own charge-pump capacitor (c1), but the reservoir capacitor (c2) serves all devices (figure 5). increase c2? 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. max16945 2 5 1 v out = (2v in ) - (v fd1 ) - (v fd2 ) c2 +v in c1 34 6 v out = -v in c4 d1 d1, d2 = 1n4148 c3 d2 shdn figure 6. combined doubler and inverter max16945 4 1 gnd out v+ r l figure 7. heavy load connected to a positive supply max16945 max16945 2 1 v out c2 2 +v in c1 c1 3 3 446 5 5 6 1 v out = -v in r out = r out of single device number of devices shdn figure 5. paralleling max16945s to reduce output resistance max16945 max16945 2 1 v out c2 2 +v in c1 c2 shdn c1 3344 6 55 6 1 v out = -nv in ? figure 4. cascading max16945s to increase output voltage downloaded from: http:///
max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications 8 maxim integrated package type package code document no. 6 sot23 u6f+6 21-0058 chip information process: bicmos package information for the latest package outline information and land patterns (foot-prints), 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. downloaded from: http:///
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 specifications without notice 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 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 _________________________________ 9 2015 maxim integrated products, inc. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max16945 30ma inverting charge pump in sot23 for emi-sensitive automotive applications revision history revision number revision date description pages changed 0 8/08 initial release ? 1 6/09 updated ordering information 1 2 6/15 updated package code pacage information 8 downloaded from: http:///
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