tc1240-1 7/7/00 tc1240 ? 2001 microchip technology inc. ds21516a positive doubling charge pump with shutdown in a sot-23 package general description the tc1240a is a doubling cmos charge-pump volt- age converter in a small 6-pin sot-23a package. tc1240a doubles an input voltage which can range from +2.5v to +5.5v. conversion efficiency is typically >99%. internal oscillator frequency is 160khz for the tc1240a. the tc1240a has an active high shutdown which limits the current consumption of the device to less than 1 a. external component requirement is only two capacitors for standard voltage doubler applications. all other circuitry, including control, oscillator, power mosfets are integrated on-chip. typical supply current is 180 a and the device is available in a 6-pin sot-23a surface mount package. features charge pump in 6-pin sot-23a package >99% typical voltage conversion efficiency voltage doubling operates from +2.5v to +5.5v low output resistance (12 ? typical) only two external capacitors required consumes 550 a (typical) in active mode power-saving shutdown mode (1 a maximum) shutdown input fully compatible with 1.8v logic sytems applications cellular phones pagers pdas, portable data loggers battery-powered devices handheld instruments ordering information part number package temp. range tc1240aech 6-pin sot-23a ?0 c to +85 c tc1240a typical operating circuit pin configuration positive voltage doubler tc1240a v in 2 x input c + c c 1 c 2 input gnd out shdn off on 6-pin sot-23a c + c gnd tc1240aech 1 2 3 6 v in out 4 5 shdn note: *6-pin sot-23a is equivalent to eiaj sc-74
tc1240a 2 tc1240a-2 11/27/00 positive doubling charge pump with shutdown in a sot-23 package ? 2001 microchip technology inc. ds21516a absolute maximum ratings* input voltage (v in to gnd) .......................... +5.8v, ?.3v output voltage (out to gnd) ............ +11.6v, v in ?0.3v current at out pin ................................................. 50 ma short-circuit duration ?ut to gnd ................ indefinite operating temperature range ...............?0 c to +85 c thermal resistance.............................................210 c/w power dissipation (t a = +25 c) ........................... 600mw storage temperature (unbiased) ......... ?5 c to +150 c lead temperature (soldering, 10 sec) ................. +300 c *static-sensitive device. unused devices must be stored in conductive material. protect devices from static discharge and static fields. stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. these are stress ratings only and functional operation of the device at these or any other conditions above 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: t a = ?0 to +85 c, v in = +5.0v, c1 = c2 = 3.3 f , shdn = gnd, unless otherwise noted. typical values are at t a = +25 c. symbol parameter test conditions min typ max units i dd supply current r load = 550 900 a i shdn shutdown supply current shdn = v in 0.01 1.0 a v min minimum supply voltage 2.5 v v max maximum supply voltage 5.5 v i load output current 20 ma r sw sum of the r ds(on) of the i load = 20ma 4 8 ? internal mosfet switches f osc oscillator frequency t a = ?0 c to +85 c 160 khz f sw switching frequency t a = ?0 c to +85 c 40 80 125 khz v ih shutdown input logic high v in = v min to v max 1.4 v v il shutdown input logic low v in = v min to v max 0.4 v p eff power efficiency i load = 5ma 86 94 % v eff voltage conversion r load = 99 99.96 % efficiency r out output resistance i load = 20ma 12 ? (note 1) t a = ?0 c to +85 c 25 note: 1. capacitor contribution is approximately 26% of the output impedance [esr = 1 / pump frequency x capacitance)]. 2. switching frequency is one-half internal oscillator frequency. pin description pin no. (6-pin sot-23a) symbol description 1 v in power supply input. 2 gnd ground. 3 c commutation capacitor negative terminal. 4 shdn shutdown input (active high). 5 out doubled output voltage. 6 c+ commutation capacitor positive terminal.
2 tc1240a positive doubling charge pump with shutdown in a sot-23 package tc1240a-2 11/27/00 ? 2001 microchip technology inc. ds21516a detailed description the tc1240a charge pump converter doubles the voltage applied to the v in pin. conversion consists of a two- phase operation (figure 1). during the first phase, switches s2 and s4 are open and s1 and s3 are closed. during this time, c1 charges to the voltage on v in and load current is supplied from c2. during the second phase, s2 and s4 are closed, and s1 and s3 are open. during this second phase, c1 is level shifted upward by v in volts. this connects c1 to the reservoir capacitor c2, allowing energy to be delivered to the output as needed. the actual voltage is slightly lower than 2 x v in since the four switches (s1 - s4) have an on-resistance and the load drains charge from reservoir capacitor c2. applications information output voltage considerations thetc1240a performs voltage doubling but does not provide regulation. the output voltage will droop in a linear manner with respect to load current. the value of this equivalent output resistance is approximately 12 ? nominal at +25 c and v in = +5.0v. v out is approximately +10.0v at light loads, and droops according to the equation below: v droop = i out x r out v out = 2 x v in ?v droop charge pump efficiency the overall power efficiency of the charge pump is affected by four factors: (1) losses from power consumed by the internal oscil- lator, switch drive, etc. (which vary with input voltage, temperature and oscillator frequency). figure 1. ideal swiched capacitor charge pump doubler (2) i 2 r losses due to the on-resistance of the mosfet switches on-board the charge pump. (3) charge pump capacitor losses due to effective series resistance (esr). (4) losses that occur during charge transfer (from commutation capacitor to the output capacitor) when a voltage difference between the two capacitors exists. most of the conversion losses are due to factors (2) and (3) above. these losses are given by equation 1(b). (a) p loss (2, 3) = i out 2 x r out (b) ? i out 2 x [ 1 +8r switch + 4esr c1 + esr c2 ] (f pump ) c1 equation 1. the pump frequency in equation 1(b) is defined as one- half the oscillator frequency (i.e. f pump = f osc /2). the 1/(f pump )(c1) term in equation 1(b) is the effective output resistance of an ideal switched capacitor circuit (figures 2a, 2b). the remaining losses in the circuit are due to factor (4) above, and are shown in equation 2. the output voltage ripple is given by equation 3. p loss(4) = [(0.5)(c1) (4v in 2 ?v out 2 ) + (0.5)(c2)(2v out v ripple ?v ripple 2 )] x f osc equation 2. v ripple = i out +2(i out )(esr c2 ) (f osc )(c2) equation 3. figure 2a. ideal swiched capacitor model v + v out r l c1 c2 f figure 2b. equivalent output resistance c1 c2 tc1240a s1 s3 s4 s2 osc v in out = 2 x v in v in v + v out r equiv r equiv = r l c2 f x c1 1
tc1240a 4 tc1240a-2 11/27/00 positive doubling charge pump with shutdown in a sot-23 package ? 2001 microchip technology inc. ds21516a figure 3. test circuit 3 1 2 6 5 c3 c1 c2 v in v out r l tc1240 c1 vin out c1 + gnd voltage doubler device c1 c2 c3 tc1240 shdn 4 3 1 2 6 5 c3 c1 c2 v in v out r l tc1240a c vin out c + gnd device c1 c2 c3 tc1240a shdn 4 3.3 f 3.3 f 3.3 f voltage doubler the most common application for charge pump devices is the doubler (figure 3). this application uses two external capacitors - c1 and c2 (plus a power supply bypass capacitor, if necessary). the output is equal to 2 x v in minus any voltage drops due to loading. refer to table 1 and table 2 for capacitor selection. cascading devices two or more tc1240as can be cascaded to increase output voltage (figure 4). if the output is lightly loaded, it will be close to ((n + 1) x v in ) but will droop at least by r out of the first device multiplied by the i q of the second. it can be seen that the output resistance rises rapidly for multiple cascaded devices. for the case of the two-stage tripler output resistance can be approximated as r out = 2 x r out1 + r out2, where r out1 is the output resistance of the first stage, and r out2 is the output resistance of the second stage. figure 4. cascading multiple devies to increase output voltage c1a c1b c2a 3 4 2 6 2 5 1 1 5 6 c2b v in v out v out = (n + 1) v in tc1240a "1" tc1240a "n" shdn shdn c+ gnd c out v in v in out c gnd c+ 3 4 capacitor selection in order to maintain the lowest output resistance and output ripple voltage, it is recommended that low esr capacitors be used. additionally, larger values of c1 will lower the output resistance and larger values of c2 will reduce output ripple. (see equation 1(b)). table 1 shows various values of c1 and the correspond- ing output resistance values @ +25 c. it assumes a 0.1 ? esr c1 and 0.9 ? r sw . table 2 shows the output voltage ripple for various values of c2. the v ripple values assume 5 ma output load current and 0.1 ? esr c2 . table 1. output resistance vs. c1 (esr = 0.1 ? ) tc1240a c1 ( f) r out ( ? ) 0.47 35 1 20.5 2.2 14 3.3 12 4.7 10.5 10 9.3 47 8.3 100 8.1 table 2. output voltage ripple vs. c2 (esr = 0.1 ? ) i out 5ma tc1240a c1 ( f) v ripple (mv) 0.47 142 167 2.2 30 3.3 20 4.7 14 10 6.7 47 2.5 100 1.6 input supply bypassing the v in input should be capacitively bypassed to reduce ac impedance and minimize noise effects due to the switch- ing internal to the device. the recommended capacitor should be a large value (at least equal to c1) connected from the input to gnd. shutdown input thetc1240a is disabled when shdn is high, and enabled when shdn is low. this input cannot be allowed to float.
4 tc1240a positive doubling charge pump with shutdown in a sot-23 package tc1240a-2 11/27/00 ? 2001 microchip technology inc. ds21516a figure 5. paralleling multiple devices to reduce output resistance c1a c1b 6 6 2 3 2 5 1 1 5 3 c2 v out v out = 2 x v in r out = r out of single device v in number of devices tc1240a "1" tc1240a "n" . . . . . . shdn shdn shutdown control 4 4 v in paralleling devices to reduce the value of r out , multiple tc1240as can be connected in parallel (figure 5). the output resistance will be reduced by a factor of n where n is the number of tc1240as. each device will require its own pump capacitor (c1x), but all devices may share one resevoir capacitor (c2). however, to preserve ripple performance the value of c2 should be scaled according to the number of paralleled tc1240as. layout considerations as with any switching power supply circuit good layout practice is recommended. mount components as close together as possible to minimize stray inductance and capacitance. also use a large ground plane to minimize noise leakage into other circuitry. tc1240 demo card the tc1240a demo card is a 1.25 x 1.0 card contain- ing a tc1240a and all of the necessary external compo- nents that allow the user to evaluate the device s ability to generate a 2x non-regulated output voltage. the demo card is fully assembled with the required external capacitors along with a variable load resistor that allows the user to vary the output load current of the output stage. for conve- nience, several test points and jumpers are available for measuring various voltages and currents on the circuit board. figure 6. tc1240a demo card schematic
tc1240a 6 tc1240a-2 11/27/00 positive doubling charge pump with shutdown in a sot-23 package ? 2001 microchip technology inc. ds21516a figure 6 is a schematic of the tc1240a demo card, and figure 7 shows the assembly drawing and artwork for the board. table 3 lists the voltages that are monitored by the test points and table 4 lists the currents that can be measured using the jumpers or the specific jumper function. figure 7. tc1240a demo card assembly drawing and artwork table 3. tc1240a demo card test points test point voltage measurement tp1 demo card power supply input[+2.5v to +5.5v] tp2 ground tp3 ground tp4 tc1240a output (2 x vin) tp5 tc1240a shdn input tp6 tc1240a vin supply voltage tp7 external shdn input table 4. tc1240a demo card jumpers jumper current measurement / jumper function j1 tc1240a quiescent current j2 tc1240a load current j3 tc1240a shdn input current j4 connect external shdn input to vin (i.e. shdn enable)
6 tc1240a positive doubling charge pump with shutdown in a sot-23 package tc1240a-2 11/27/00 ? 2001 microchip technology inc. ds21516a typical characteristics supply current vs. supply voltage (no load) 0 100 200 300 400 500 600 700 2.00 3.00 4.00 5.00 6.00 supply voltage (v) supply current vs. temperature (no load) 0 50 100 150 200 250 300 350 400 450 -50 -25 0 25 50 75 100 125 temperature (?c) output source resistance vs. supply voltage (with rload = 1k) 0 5 10 15 20 2.00 3.00 4.00 5.00 6.00 supply voltage (v) output source resistance vs. temperature (with rload = 1k) 0 5 10 15 20 25 -50 -25 0 25 50 75 100 125 temperature (?c) output voltage drop vs load current 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 5 10 15 20 25 30 35 40 45 50 load current (ma) power efficiency vs load current 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 5 10 15 20 25 30 35 40 45 50 load current (ma) \ v in = 4.0v v in = 2.8v v in = 2.8v v in = 4.0v v in = 2.8v v in = 4.0v v in = 2.5v v in = 4.5v v in = 3.5v
tc1240a 8 tc1240a-2 11/27/00 positive doubling charge pump with shutdown in a sot-23 package ? 2001 microchip technology inc. ds21516a taping form user direction of feed user direction of feed device marking component taping orientation for 6-pin sot-23a (eiaj sc-74) devices device marking pin 1 pin 1 standard reel component orientation for tr suffix device (mark right side up) reverse reel component orientation for rt suffix device (mark upside down) w p package carrier width (w) pitch (p) part per full reel reel size 6-pin sot-23a 8 mm 4 mm 3000 7 in carrier tape, number of components per reel and reel size & represent part number code + temperature range and (two-digit code) tc1240a code 1240aech en ex: 1240aech = represents year and 2-month code represents lot id number marking 6-pin sot-23a 3 switching frequency vs. temperature 0 20 40 60 80 100 -50 -25 0 25 50 75 100 125 temperature (?c) v in = 2.8v v in = 4.0v switching frequency (khz) typical characteristics (cont.) e n
8 tc1240a positive doubling charge pump with shutdown in a sot-23 package tc1240a-2 11/27/00 ? 2001 microchip technology inc. ds21516a package dimensions dimensions: inches (mm) 6-pin sot-23a (eiaj sc-74) .069 (1.75) .059 (1.50) .122 (3.10) .098 (2.50) .075 (1.90) ref. .020 (0.50) .014 (0.35) .037 (0.95) ref. .118 (3.00) .110 (2.80) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00) .024 (0.60) .004 (0.10) 10 max. .008 (0.20) .004 (0.09)
tc1240a 10 tc1240a-2 11/27/00 positive doubling charge pump with shutdown in a sot-23 package ? 2001 microchip technology inc. ds21516a information contained in this publication regarding device applications and the like is intended through suggestion only and ma y be superseded by updates. it is your responsibility to ensure that your application meets with your specifications. no representation or warrant y is given and no liability is assumed by microchip technology incorporated with respect to the accuracy or use of such information, or infringement of patent s or other intellectual property rights arising from such use or otherwise. use of microchip ? s products as critical components in life support systems is not authorized except with express written approval by microchip. no licenses are conveyed, implicitly or otherwise, except as maybe explicitly expressed herein, under any intellec- tual property rights. the microchip logo and name are registered trademarks of microchip technology inc. in the u.s.a. and othe r countries. all rights reserved. all other trademarks mentioned herein are the property of their respective companies. all rights reserved. ? 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