| LIN AR LTC1044/7660 TECHNOLOGY FEATURES = Plug-In Compatible with 7660 with These Additional Features: Guaranteed Operation to 9V, with No External Diode, Over Full Temperature Range Boost Pin (Pin 1) for Higher Switching Frequency e Lower Quiescent Power e Efficient Voltage Doubler 200A Max. No Load Supply Current at 5V = 97% Min. Open Circuit Voltage Conversion Efficiency = 95% Min. Power Conversion Efficiency = Wide Operating Supply Voltage Range, 1.5V to 9V = Easy to Use a Commercial Device Guaranteed Over 40C to 85C Temperature Range APPLICATIONS Conversion of +5V to +5V Supplies = Precise Voltage Division, VouT =Vin/2 + 20ppm Voltage Multiplication, Vout = +nVin @ Supply Splitter, Vout = +Vs/2 Switched Capacitor Voltage Converter DESCRIPTION The LTC1044 is a monolithic CMOS switched capacitor voltage converter which is manufactured using Linear Technologys enhanced LTCMOS silicon gate process. The LTC 1044 provides several voltage conversion func- tions: the input voltage can be inverted (Vout = Vin), doubled (Vout = 2Vin ), divided (Vout = Vin /2) or multi- plied (Vout = + nVin). Designed to be pin-for-pin and functionally compatible with the popular 7660, the LTC1044 provides significant features and improvements over earlier 7660 designs. These improvements include: full 1.5V to 9V supply op- eration over the entire operating temperature range, with- out the need for external protection diodes; 2% times lower quiescent current for greater power conversion effi- ciency; and a boost function which is available to raise the internal oscillator frequency to optimize performance in specific applications. Although the LTC 1044 provides significant design and . performance advantages over the earlier 7660 device, it still maintains its compatibility with existing 7660 designs. LTCMOS is a trademark of Linear Technology Corp. Generating CMOS Logic Supply from 2 Mercury Batteries Supply Current vs Supply Voltage 400 2 Ry = 00 ww ~ o 280 240 ae n Oo GUARANTEED SUPPLY CURRENT ig = 3pA = rR oO POINT TYPICAL NO LOAD INPUT CURRENT, Is (yA) 3 o & 8 Oo 012 3 4 5 6 7 8 9 10 SUPPLY VOLTAGE, V+ (V) LI WNLTC1044/7660 ABSOLUTE MAXIMUM RATINGS (Notes 1 and 2) Supply Voltage ..... 0.0.0.0... ce eee eae 9.5V Input Voltage on Pins 1, 6 and 7 (Note2)............. 0.3V<Vin <VT +0.3V CurrentintoPin6 ................ 0.0.0, 20pA Output Short Circuit Duration (Vt <5.5V) 0... Continuous Operating Temperature Range LTC1044C ............... 40C <Ta <85C LTC1044M .............. 55C <Ta =125C Storage Temperature Range...... 65C to + 150C Lead Temperature (Soldering, 10sec.) ........ 300C PACKAGE/ORDER INFORMATION ror View ORDER PART NUMBER (Case) LTC1044CH LTC1044MH CAP METAL CAN H PACKAGE TOP VIEW 7 + mons Lt = LTC1044CJ8 re ose LTC1044CN8 GROUND |3 6] W on 5 he LTC1044MJ8 HERMETIC DIP J8 PACKAGE PLASTIC DIP NB PACKAGE ELECTRICAL CHARACTERISTICS V+ =5V, T,=25C, Test Circuit Figure 1, unless otherwise specified. LTC1044M LTC1044C SYMBOL | PARAMETER CONDITIONS MIN TYP MAX | MIN TYP MAX UNITS Is Supply Current R, = , Pins 1 and 7 No Connection 60 200 60 200 pA R, = 00, Pins 1 and 7 V* =3V 20 20 pA ver Minimum Supply Voltage | Ry = 10k e| 1.5 1.5 V vty Maximum Supply Voltage | R, = 10k (Note 3) e ce) 9 v Rout Output Resistance 1, =20mA, fosc = 5kHz 100 100 Q e 150 130 Q V+ =2V, 1, =3mA, fog = 1kHz e 400 325 a fosc Oscillator Frequency Cosc = 1pF (Note 4) V+ =5V @|5 kHz V+=a2v @)1 1 kHz Pere Power Efficiency Ry =5kQ, tosc = 5kHz 95 98 95 98 % Vouterr | Voltage Conversion RL =o 97 99.9 97 99.9 % Efficiency lasc Oscillator Sink or Source | Vos. =OV or Vt Current Pin 1=0V e 3 3 pA Pind =vt e 20 20 pA The @ denotes the specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Connecting any input terminal to voltages greater than V* or less than ground may cause destructive latch-up. it is recommended that no inputs from sources operating from external supplies be applied prior to power-up of the LTC 1044. 9-10 Note 3: The LTC1044 is guaranteed to operate with alkaline, mercury or NiCad 9V batteries, even though the initial battery voltage may be slightly higher than 9.0V. Note 4: fcc is tested with Cosc = 100pF to minimize the effects of test fixture capacitance loading. The 1pF frequency is correlated to this 100pF test point, and is.intended to simulate the capacitance at pin 7 when the device is plugged into a test socket and no external capacitor is used. WeeLTC1044/7660 TYPICAL PERFORMANCE CHARACTERISTICS (using test circuit shown in Figure 1) Operating Voltage Range vs Temperature Qa SUPPLY VOLTAGE, V+ (V) 1Oo nu yO hm @ NN wo w 55 -25 0 2 68075 100 AMBIENT TEMPERATURE, Ta (C) 125 Power Conversion Efficiency vs Load Current for Vt =2V Vt=2V Ty= 25C C1=C2=10pF fosgo= 1kHz 100 Perr sea8s8e& 8848 POWER CONVERSION, EFFICIENCY, Perr (%) Q 0 1 2 3 4 5 6 7 LOAD CURRENT, |, (mA) Output Voltage vs Load Current for V+ =2V 2.5 2 Ta=25C Vt=2V 15 fosc = 1kHz S 1 8 0.5 3 0 > 5-05 ~ > 5 SLOPE = 2500 | = ot on = | t mon wn Oo 0 1 2 3 4 6 7 LOAD CURRENT, i, (mA) 8 3 10 SUPPLY CURRENT (mA) Power Efficiency vs Oscillator Frequency 100 = Ty=25 ww 01=C2 wo eo 100.F & 10yF TaF wo + {p= imA Coron oo wo oOo O&O POWER EFFICIENCY, Perr (%) @ fe uF a N a aP 2 oO ik 10k OSCILLATOR FREQUENCY, fogc (Hz) 100k Power Conversion Efficiency vs Load Current for V+ =5V 100 100 = Vt+=5V = 90 Ta=25C 90 + C1=C2=10pF a 80 fogc = SkHz 80 _ & 70 70 = a = S sos 2 a 50 50 5 Oo oO am 40 > a & 2 30 305 8 ex 20 20 = 5 10 10 0 0 0 2 30 40 50 60 70 LOAD CURRENT, 1, (mA) Output Voltage vs Load Current for V+ =5V Ta=25C Vt=5V fosc =5kHz = uu oo 5 o => ee a 5 Oo 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT, |, (mA) Output Resistance vs Oscillator Frequency 500 Ta=25C V+=5V 1, =10mA @ 100 Oo oc 300 =z 5 wn = = 900 C1=C2=tpF eK > & > 100 C1= 0 100 1k 10k 100k OSCILLATOR FREQUENCY, foge (Hz) Output Resistance vs Supply Voltage 1000 1, =3mA Ta= 25C s 2 oc g = & 100 g ac e > & 2 oO 10 012 3 4 5 6 7 8 9 10 SUPPLY VOLTAGE, V+ (V) Output Resistance vs Temperature 400 C1=C2= 10pF 360 Se 320 280 z fm 240 OUTPUT RES! B V+=5V fosc=5kHz a -55 -25 0 2 86600)0= 75 AMBIENT TEMPERATURE (C) 100-125 7 wee 9-11LTC1044/7660 TYPICAL PERFORMANCE CHARACTERISTICS (Using Test Circuit Shown in Figure 1) Oscillator Frequency as a Function of Cosc Voltage = 00k 100k 10k 10k 1k OSCILLATOR FREQUENCY, fgg (Hz) x OSCILLATOR FREQUENCY, fase (Hz) 10 ~~ = 1 10 100 1k 10k 0 1 EXTERNAL CAPACITOR (PIN 7 TO GROUND), Cosc (pF) Oscillator Frequency vs Supply 2 3 4 5 6 7 8 9 10 SUPPLY VOLTAGE, V+ (V) Oscillator Frequency vs Temperature Cosc = OnF Ta=25C OSCILLATOR FREQUENCY, fgg (kHz) 100 125 55 -25 0 25 50 75 AMBIENT TEMPERATURE (C) TEST CIRCUIT VY V+ (5V) c C1 10pF i3} woe FR < EXTERNAL oe LT61044 OSCILLATOR A, $ |. A vvv < Ei] =LELLE Ee th | > Vout Cosc be TT Ty 10uF i 4 t Figure 1 APPLICATIONS INFORMATION Theory of Operation To understand the theory of operation of the LTC1044, a review of a basic switched capacitor building block is helpful. In Figure 2, when the switch is in the left position, capacitor C1 will charge to voltage V1. The total charge on C1 willbe qi =C1V1. The switch then moves to the right, discharging C1 to voltage V2. After this discharge time, the charge on C1 is q2=C1V2. Note that charge has been transferred from the source, V1, to the output, V2. The amount of charge transferred is: Aq=q1 q2=C1(V1 V2). lf the switch is cycled f times per second, the charge transfer per unit time (i.e., current) is: | =fx Ag=txC1(V1V2). v1 v2 f RL Figure 2. Switched Capacitor Building Block 9-12 LI WeeLTC1044/7660 APPLICATIONS INFORMATION Rewriting in terms of voltage and impedance equivalence, ;v1-V2 _ Vi-V2. (1/fC1) ~~ Requiv A new variable, Requiv, has been defined such that Requiv =1/fC1. Thus, the equivalent circuit for the switched capacitor network is as shown in Figure 3. Reauiv v1 v2 2 Ru 1 Requ=az~ Figure 3. Switched Capacitor Equivalent Circuit Examination of Figure 4 shows that the LTC 1044 has the same switching action as the basic switched capacitor building block. With the addition of finite switch on- resistance and output voltage ripple, the simple theory, although not exact, provides an intuitive feel for how the device works. V+ (8} BOOST Osc mp +2 OSC (7) ( i | L 7x ! + (i) jot C1 For example, if you examine power conversion efficiency as a function of frequency (see typical curve), this simple theory will explain how the LTC 1044 behaves. The loss, and hence the efficiency, is set by the output impedance. As frequency is decreased, the output impedance will eventually be dominated by the 1/fC1 term and power efficiency will drop. The typical curves for power effi- ciency versus frequency show this effect for various capacitor values. Note also that power efficiency decreases as frequency goes up. This is caused by internal switching losses which occur due to some finite charge being lost on each switching cycle. This charge loss per unit cycle, when muitiplied by the switching frequency, becomes a current loss. At high frequency this loss becomes significant and the power efficiency starts to decrease. LV (Pin 6) The internal logic of the LTC1044 runs between V+ and LV (pin 6). For V* greater than or equal to 3V, an internal switch shorts LV to GND (pin 3). For V+ less than 3V, the LV pin should be tied to GND. For V* greater than or equal to 3V, the LV pin can be tied to GND or left floating. " j WwW j (6) CLOSED WHEN V+>3.0V Figure 4. LTC1044 Switched Capacitor Voltage Converter Block Diagram LY Witne 9-13LTC1044/7660 APPLICATIONS INFORMATION OSC (Pin 7) and Boost (Pin 1) The switching frequency can be raised, lowered or driven from an external source. Figure 5 shows a functional diagram of the oscillator circuit. By connecting the boost pin (pin 1) to V+ , the charge and discharge current is increased and, hence, the frequency is increased by approximately 7 times. Increasing the fre- quency will decrease output impedance and ripple for higher load currents. Loading pin 7 with more capacitance will lower the fre- quency. Using the boost (pin 1) in conjunction with ex- ternal capacitance on pin 7 allows user selection of the frequency over a wide range. Driving the LTC 1044 from an external frequency source can be easily achieved by driving pin 7 and leaving the boost pin open, as shown in Figure 6. The output current from pin 7 is small, typically 0.5A, so a logic gate is capable of driving this current. The choice of using a CMOS logic gate is best because it can operate over a wide supply voltage range (3V to 15V) and has enough voltage swing to drive the internal Schmitt trigger shown 5G ' BOOST \ (1) > y+ o 9 Osc SCHMITT 6 TT (7) | TRIGGER l == ~ 14pF | LV (6) na Figure 5. Oscillator 5-14 in Figure 5. For 5V applications, a TTL logic gate can be used by simply adding an external pull-up resistor (see Figure 6). External Diode (Dx ) Previous circuits of this type have required a diode be- tween Vout (pin 5) and the external capacitor, C2, for voltages above 6.5V (5V for military temperature range). Because of improvements which have been made in the LTC1044 circuit design and Linear Technology's silicon gate CMOS process, this diode is no longer required. The LTC1044 will operate from 1.5V to 9V, without the protec- tion diode, over all temperature ranges. It should, however, be noted that the LTC1044 will operate without any problems in existing 7660 designs which use the protection diode, as long as the maximum operating voltage (V* ) of SV is not exceeded. Capacitor Selection External capacitors C1 and C2 are not critical. Matching is not required, nor do they have to be high quality or tight tolerance. Aluminum or tantalum electrolytics are excellent choices, with cost and size being the only consideration. REQUIRED FOR TTL LOGIC EY rotons. Figure 6. External Clocking LI WieLTC1044/7660 a TYPICAL APPLICATIONS Negative Voltage Converter Figure 7 shows a typical connection which will provide a negative supply from an available positive supply. This cir- cuit operates over full temperature and power supply ranges without the need of any external diodes. The LV pin (pin 6) is shown grounded, but for Vt = 3V it may be floated, since LV is internally switched to ground (pin 3) for Vt >3V. The output voltage (pin 5) characteristics of the circuit are those of a nearly ideal voltage source in series with an 800 resistor. The 802 output impedance is composed of two terms: 1) the equivalent switched capacitor resist- ance (see Theory of Operation) and 2) a term related to the on-resistance of the MOS switches. At an oscillator frequency of 10kKHz and C1 =10yF, the first term is: R = iO EQUIV (fosc/2) x1 1 C= 000. 5x 10 x10 10 Notice that the above equation for Requiv is not a capacitive reactance equation (Xc = 1/@C) and does not contain a 27 term. The exact expression for output impedance is extremely complex, but the dominant effect of the capacitor is clearly shown on the typical curves of output impedance and power efficiency versus frequency. For C1 =C2=10,F, the out- put impedance goes from 600 at fosc =10kHz to 2002 at fosc = 1kHz. As the 1/fC term becomes large compared to the switch on-resistance term, the output resistance is de- termined by 1/fC only. Voltage Doubling Figure 8 shows two methods of voltage doubling. In Figure 8a doubling is achieved by simply rearranging the connection of the two external capacitors. When the input voltage is less than 3V, an external 1MQ resistor is required to ensure the oscillator will start. It is not re- quired for higher input voltages. In this application the ground input (pin 3) is taken above V+ (pin 8) during turn-on, making it prone to latch-up. The latch-up is not destructive but simply prevents the circuit from doubling. Resistor R1 is added to eliminate the problem. In most cases 2000 is suffi- cient. It may be necessary in a particular application to increase this value to guarantee start-up. The voltage drop across R1 is : Vay =2 Xloyt XR71. If this voltage exceeds two diode drops (1.4V for silicon, 0.8V for Schottky), the circuit in Figure 8a is recom- mended. This circuit will never have a start-up problem. V+ (1.5V TO 9.0V) 10,F Th ves Twin Tas Tmax [6 }- a REQUIRED FOR V+ <3V aE + Vour= * Vin (1.5V TO 9V) Figure 7. Negative Voltage Converter 1N914 Vin >}\ lw. 7 (1.5V TO 9.0V) Ri > fy ag ooas T] [ae 2Viy (3.0 TO 18V) rt ta ia EIEIO 5 C1 wekt Lois c2 3 ee Pa 6k yRequinco FOR Voaur=2(Vin1 10pF -{3] ee - 3 =e ios fy ey Wt <3.0v oureewe | a] 5 3; : 4 10yF 10pF sc1M@}_ pequIRED FOR = = 7 T Li Lv <sov = (a) Figure 8. Voltage Doubler (b) LY We 9-15LTC1044/7660 TYPICAL APPLICATIONS Ultra Precision Voltage Divider An ultra precision voltage divider is shown in Figure 9. To achieve the 0.0002% accuracy indicated, the load cur- rent should be kept below 100nA. However, with a slight loss in accuracy, the load current can be increased. Battery Splitter A common need in many systems is to obtain (+) and () supplies from a single battery or single power supply system. Where current requirements are smail, the cir- cuit shown in Figure 10 is a simple solution. \t provides symmetrical + output voltages, both equal to one half the input voltage. The output voltages are both refer- enced to pin 3 (output common). If the input voltage be- tween pin 8 and pin 5 is less than 6V, pin 6 should also be connected to pin 3, as shown by the dashed line. Paralleling for Lower Output Resistance Additional flexibility of the LTC 1044 is shown in Figures 11, 12 and 13. V+ (3V TO 18V) qo. 2] eT 01 { =e ters 19 _| * we 1 4 . . 5 Xe + 0.002% dpe ma ea 4 th. c2 \ = TwinSTasT i a I= 1000A T REQUIRED FOR V+ <6V Figure 9. Ultra Precision Voltage Divider Figure 11 shows two LTC1044s connected in parallel to provide a lower effective output resistance. If, however, the output resistance is dominated by 1/fC1, increasing the capacitor size (C1) or increasing the frequency will be of more benefit than the paralleling circuit shown. Figures 12 and 13 make use of stacking two LTC 1044s to provide even higher voltages. In Figure 12, a negative voltage doubler or tripler can be achieved, depending upon how pin 8 of the second LTC 1044 is con- nected, as shown schematically by the switch. Figure 13 indicates a similar circuit which can be used to obtain positive tripling, or even quadrupling (the doubler circuit appears in Figure 8a. In both of these circuits, the available output current will be dictated/decreased by the product of the individual power conversion efficien- cies and the voltage step-up ratio. Epp + 09/2 (4.50) [7] FE y= REOUIRED FOR Va<6v [Ss }-L4 Vp/2 (4.5V) ty ' (2 + 10uF OUTPUT COMMON 3VsVg< 18V Figure 10. Battery Splitter 9-16 LY WILTC1044/7660 TYPICAL APPLICATIONS (V+) pM oJ Gy Be 2 7 2b. 7 oi T= LTC1044 a ct [. re itc1044 oa 10uF : : 10uF : : . i 4 Hs *] . TLE 5} > Vour= (V*) 4/4 CD4077 Lice im al THE EXCLUSIVE NOR GATE SYNCHRONIZES BOTH LTC 1044s TO MINIMIZE RIPPLE Figure 11. Paralleling for Lower Output Resistance Vt FOR Vaut= 3V +> FOR Voyt = 2Vt a PIEPIEI 10pnF Figure 12. Stacking for Higher Voltage iNg14 V+ (+5V) PI 1N914 tor De 8 p> Vour +2 ay 7 2002 WT Bh, | iw 4 * fee a + 7 fi fal v 3 Bos Oye wet 2000 & 2] urctoss [7] 4). <M Our { Ts oa tour i " = wt ike f FOR Vgyt = 3V * FOR Voy =4V + 15V) ~__ J (4 20V (+ oO (+20V) *REQUIRED FOR V+ <3.0V Figure 13. Voltage Tripler /Quadrupler LI We 5-17 TECHNOLOGYLTC1044/7660 TYPICAL APPLICATIONS 200k Ny 8.2k 2 Vin" Z Jv 3], 50k ant 6 LM10 ? bOUTPUT 3k 1 a coe > 10yF 8 - 4 Nr 50k 200k | - 39k 2 94 Vin= | Vout| +0.5V LOAD REGULATION +0.02%, OmA TO 15mA b+ 5V > 32200 a 0.33 pF | | OUTPUT OV TO 3.5V 1.2V REFERENCE TO = 2k ' A/D CONVERTER FOR $ +00K al | vf GAIN Ops! TO 350s RATIOMETRIC OPERATION (1mA MAX) yy > | | 3 TRIM hm gue LT1004 mY 10k 301k" 4 4@ LTI013 Ie Jy 1.2V ZERO $V ~ | : TRIM 3500 PRESSURE | $ so00* | TRANSDUCER { | i = _ ov r r 5 | = = 7 KX al "1 8 = ~1yfO I | . | 0.1yF *4% FILM RESISTOR " ne PRESSURE TRANSDUCER BLH/DHF-350 (CIRCLED LETTER IS PIN NUMBER) Figure 15. Single 5V Strain Gauge Bridge Signal Conditioner 5-18 LIT WeLTC1044/7660 TYPICAL APPLICATIONS 01 2009 : ' TT tr +5V OUTPUT ; me vm > = sOnF 4 24.8 on 2 4 I, | - ANA 1 REF | + Ww AMP EVEREADY EXP-30 <== | +, | ~ | | 1 mio I l | I 2 330k I, t 1k | Ann 6 op I I | --- 1N914 150k o Wm iF a 100k Figure 16. Regulated Output +3V to +5V Converter 2N2219 Vour=5V Ms +12V > ron SB 120k 7 3 SHORT CIRCUIT E 8 , PROTECTION 5 FEEDBACK AMP ms [TH TTT TIO OOF ae 4 EVEREADY -91 CELLS a al | Loan l, Vv | LT1013 al | | | 111004 re 1.2V + , 30k 1.2k ouTPUuT o.019 ADJUST 9 Voropout AT 1mA = 1mv ~ ~ Voropout AT 10mA = 15mv = Voropout AT 100mA = 95mV Figure 17. Low Dropout 5V Regulator LY WB 5-19LTC1044/7660 PACKAGE DESCRIPTION H Package J8 Package Metal Can 8 Lead Hermetic DIP 0.355 0,370 (9.017 9.398) 7 cm i DIA ae. 9:305 = 0.335 0.220-0.310 0.040 rr 8) (5.588 7.874) (1.016) 0.050 A et 4 MAX 01.270) 0.165 0.185 ao. { MAX (4.151 4.699) ! t ET TING TUNE tHE PANE 0.500 0.750 MAX 4 (12.70 19.05) @. A ' 148) | a 0.016 0.021 0.405 (0.406 0.533) (10.29) TP 0.200 MAX (5.080) 0,015 ~0.060_ 0.005 Max (0.3811.524) 1G Zo 0.027 - 0.045 MIN 0.027-9.0394 AN (0-688 1.143) } | (0.686 0.954) t ] GLASS q h 0.150 i : e 0,125 0.200 (3.810) u Ms (3.175 5.080) mae T a oosoo070 F 0.070 o_qge 0,008 0.015 9.100 ! 0.100 (0762-778 1.778) wet fears oI (e208 0381 (2.540) ee 0.014-0.973. ouno.ges 0.290 -0.320 a fan TYP (0.356 0.584) sso 0. 534) (7.366 8.128) INSULATING STANDOFF NOTE: DIMENSIONS IN INCHES (MILLIMETERS) UNLESS OTHERWISE NOTED NOTE: DIMENSIONS IN INCHES (MILLIMETERS) LEADS WITHIN 0.007 OF TRUE POSITION (TP) AT GAUGE PLANE Tjmax Op Oe Tmax Of 180C 150C/W | 45C/W N8 Package 150C 100C/W 8 Lead Plastic om 4 1 qt 0,240 0.280 (6.096 7.112} 5 8 f TTT | 0.040 0.060 (1.016 MAX (1.524) sa 0.370-0.400 0.020, (9.400 10.16) (0.508) ay ae 2.005, T?+5 watt (0.127) MIN A 0.155 0.175 (3.937 4.445) 0.125 0.130 0.150.145 ' \ (3.175 3.362) (2.921 3.683) i ht u 0,030 0.060 o_4ge 0.008 0.015 t 100 {0.7621.524) wet beams (0.203 0.381) ee mend Tye TP we 0.0140.023 0.290-0.310 TYP (0.356 0.584) (7.366 7.874) TYP 9-20 NOTE: DIMENSIONS IN INCHES (MILLIMETERS) UNLESS OTHERWISE NOTED LEADS WITHIN 0.007 OF TRUE POSITION (TP) AT GAUGE PLANE Tymax 100C Oa 130C /W LY Wee