19-0896; Aev 1; 7/96 MAXIM +5V to +10V Voltage Converters General Description The MAX68G/MAX681 are monolithic, CMOS, dual charge-pump voltage converters that provide +10V out puts from a +5 input voltage. The MAX680/MAX681 pro- vide both a positive step-up charge pump te develop +10V from +5V input and an inverting charge pump to generate the -10V output. Both parts have an on-chip, 8kHz oscillator. The MAX681 has the capacitors internal to the package, and the MAX680 requires four external capacitors to produce both positive and negative voltages from a single supply. The output source impedances are typically 150, pro- viding useful output currents up to 10mA. The low quies- cent current and high efficiency make this device suitable for a variety of applications that need beth positive and negative voltages generated from a single supply. The MAX&864/MAX865 are also recommended for new designs. The MAX864 operates at up to 2O0KHz and uses smaller capacitors. The MAX865 comes in the smaller UMAX package. Applications The MAX680/MAX681 can be used wherever a single posilive supply is available and where positive and nega- tive voltages are required. Common applications include generating +6V from a 8V battery and generating +10V from the standard +5V logic supply (for use with analog circuitry). Typical applications include: +6V from 3V Lithium Cell Hand-Held Instruments Data-Acquisition Systems Panel Meters +10 from +5V Logic Supply Battery-Operated Equipment Operational Amplifier Power Supplies Pin Configurations TOP VIEW . ee . a- [1 Ate [4 a] vec Features -*?- + + + 95% Voltage-Conversion Efficiency 85% Power-Conversion Efficiency +2V to +6V Voltage Range Only Four External Capacitors Required (MAX680) No Capacitors Required (MAX681) 500A Supply Current Monolithic CMOS Design Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX680CPA OT to +70 8 Plastic DIP MAX680CSA OC to +70 8 Narrow SO MAX680C/D OT to+70C Dice MAX680EPA -40C to +85C 8 Plastic DIP MAX680ESA -40C to +85C 8 Narrow SO MAX680MJA -55C to +125C 8 CERDIP MAX681CPD 0T to +70C 14 Plastic DIP MAX681EPD -40C to +85C 14 Plastic DIP Typical Operating Circuits +4V c14 Yee AAAXLM ct MAX6BO V+ 4,7 pF 4.7 pF r HOV Cit 47 UF -10 C2- gyp MAXIM ct- [2 Ha] ny ane . cc __________ on Maxeag 7 | cts ot ar +5 fo rev 37 MAXIMA [21 Yc Voc ay . [_ ca 8} Yeo gay [a Mf AX81 it] Veo FOUR me REQUIRED MAXI MAXB61 ONLY ve [a] rs | GND ce. [5 | io] Wa | MAXB8i , = _ _< oo 10 cz: [6 | re | eno GND BIP/SO ve GF fa | sno GND GND 45 19 10 CONVERTER DIP MA AXLAA Maxim integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 L89XVN/089XVWMAX680/MAX681 +5V to +10V Voltage Converters ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70C) 8-Pin Plastic DIP (derate 9.09mW/C above +70C) .....727mW 8-Pin Narrow SO (derate 5.88mMW/C above +70C) ....471mW 8-Pin CERDIP (derate 8.00mMW/C above +70C) ........ 640mW 14-Pin Plastic DIP (derate 10.00mW/C above +70C) ...800mW Storage Temperature Range ......... ee -65 to +160C Lead Temperature (soldering, 10sec) .....0..... cee +300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are siress ratings only, and functional operation of the device at these or any oiher conditions beyond those indicated in the operational sections of ihe specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (Vcc = +5V, test circuit Figure 1, Ta = +25C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS Voc = 3V, Ta = +25C, RL = 0.5 1 Voc = 5V, Ta = +25C, Rl = & 1 2 Supply Current Voc = 5V, OC s Tas +70, RL = 2.5 mA Voc = 5V, -40C < Tas +85, RL = 3 Voc = 5V, -55C <= Tas 4125, RL = 3 Supply-Voltage Range MIN s Tas MAX, RL = 10k 2.0 15106060 6.0 Vv IL+ = 10mA, IL- = OMA, Veco = 5YV, Ta = 425C 150 250 IL+ = 5mA, IL- = OMA, Voc = 2.8V, Posilive Charge-Pump Th = 425%C L Ce 180 300 : Q Output Source Resistance Lt = 10mA, OCs TAS +70C 325 IL- = OMA, 40 s Tas +85C 350 Voc = 5V 55C Ss Tas +125C A400 IL- = 10mA, IL+ = OmA, V+ = 10V, Ta = +25 90 150 IL- = 5mA, IL+ = OmA, V+ = 5.6, Negative Charge-Pump Ta = 425C 110 175 : = QO Output Source Resistance |= 10mA, OCs TAS +70C 200 IL+ = OmA, -40C<Tas4+85C 200 V+ = 10V 55C < TAS +125C 250 Oscillator Frequency 4 8 kHz Power Efficiency Ri = 10kQ 85 % Voltage-Conversion V+, RL = 95 99 9 Efficiency V-, RL = 90 97 2 MA AXLAA+5V to +10V Voltage Converters Typical Operating Characteristics (Ta = +25C, unless otherwise noted.) OUTPUT RESISTANCE OUTPUT VOLTAGE SUPPLY CURRENT vg. SUPPLY VOLTAGE vs. LOAD CURRENT vs. SUPPLY VOLTAGE 250 5 10 : 2.0 z \ Ci-C4=10mF Ug SS Ve v8. It i i g ZL g g g 9 Le=0 TE 5 200 z NX : i a a ea | Zz 15 5 ~~ Routt 8 7 ~~ = = 150 PS = Ve ve dit N\ 5 & = 0 & & NN =," ~ = ip _ a = = zoo ~ 100 Ss V+ v6. I, 2 ae 2 Ne 6 t= a a - out: = Ss te | 1) a 2.5 al 50 = 5 Ve ve. IL. Lt =O NA 0 4 p 2.0 3.0 4.0 5.0 6.0 0 10 15 20 2.0 3.0 4.0 5.0 6.0 QUTPUT VOLTAGE vs. OUTPUT CURRENT QUTPUT SOURCE RESISTANCE QUTPUT RIPPLE vs. (FROM V+ TO V-} vs. TEMPERATURE OUTPUT CURRENT (I,+ OR IL-} 16 TTT: BY Tege5e : Maxeeo,Maxeel [= = Yoo = 8 Z oe vfs 9 = | 7 @ 5 MAXBB1 el : MI 160 Routt 2 160 Va hss, = = Ve 8 ne E a = M 2 a | Lo 57 _ = 100 = 100 AZ 3 ve 2 Le Ror Fs ar MN 2 La 5 M AXBBD 6 a pee a "| C3, C4 = 10uF v- = 60 2 50 Ay 5 | e 7 wu ax6a0 | C1--Ca = 1 qr C3, C4 = 100pF V+ AND V- 4 Lt | p 0 0 1 2 3 4 5 6 7 8 8 16 0-25 0 28 80 75 100 128 D 5 1p 15 20 OUTPUT CURRENT (mA) TEM PERATURE ( C) OUTPUT CURRENT (maj MA AXLAA 3 L89XVN/089XVWMAX680/MAX681 +5V to +10V Voltage Converters Yoo IN C1 Al MAAXIAA AT HF La 2 ctl | 47 UF | : 4 C1- G2+ MAX880 Figure 1. Test Circuit Detailed Description The MAX681 contains all circuitry needed to implement a dual charge pump. The MAX680 needs only four capacitors. These may be inexpensive electrolytic capacitors with values in the 1uF to 100uF range. The MAX681 contains two 1.5uF capacitors as C1 and Ce, and two 2.2uUF capacitors as C3 and C4. See Typical Operating Characteristics. Figure 2a shows the idealized operation of the positive voltage converter. The on-chip oscillator generates a 50% duty-cycle clock signal. During the first half of the cycle, switches S2 and $4 are open, $1 and 88 are closed, and capacitor C1 is charged to the input volt- age Voc. During the second half-cycle, $1 and $3 are open, 32 and $4 are closed, and 1 is translated upward by Vcc volts. Assuming ideal switches and no load on C3, charge is transferred onto C3 from C1 such that the voltage on C3 will be 2Vcc, generating the positive supply. Figure 2b shows the negative converter. The switches of the negative converter are out of phase from the pos- itive converter. During the second half of the clock cycle, S6 and 38 are open and $5 and S/ are closed, charging G2 from V+ (pumped up to 2Vcc by the posi- tive charge pump) to GND. In the first half of the clock a) b) Vec Figure 2. fdealized Voltage Quadrupler: a) Positive Charge Pump; b) Negative Charge Pump MA AXLAN+5V to +10V Voltage Converters cycle, $5 and $7 are open, $6 and S8 are closed, and the charge on Ce is transferred to C4, generating the negative supply. The eight switches are CMOS power MOSFETs. $1, S2, S4, and S5 are P-channel switches, while S38, S6, S7, and S8 are N-channel switches. Efficiency Considerations Theoretically, a charge-pump voltage multiplier can approach 100% efficiency under the following con- ditions: * The charge-pump switches have virtually no offset and extremely low on-resistance * Minimal power is consumed by the drive circuitry The impedances of the reservoir and pump capaci- tors are negligible For the MAX680/MAX681, the energy loss per clock cycle is the sum of the energy loss in the positive and negative converters as below: LOSSTotT = LOSSpos + LOSSNEG = VC [ (V+)? -(V+)(Voo)] + Vy C2 [ (V+)? -(V-?] There will be a substantial voltage difference between (V+ - Voc) and Vec for the positive pump, and between V+ and V-, if the impedances of pump capaci- tors C1 and Ce are high relative to their respective out- put loads. Larger G3 and C4 reservoir capacitor values reduce output ripple. Larger values of both pump and reservoir capacitors improve efficiency. Maximum Operating Limits The MAX680/MAX681 have on-chip zener diodes that clamp Vcc to approximately 6.2V, V+ to 12.4V, and V- to -12.4V. Never exceed the maximum supply volt age: excessive current may be shunted by these diodes, potentially damaging the chip. The MAX680/ MAX681 operate over the entire operating temperature range with an input voltage of +2V to +6V. MA AXLIA Applications Positive and Negative Converter The most common application of the MAX680/MAX681 is as a dual charge-pump voltage converter that pro- vides positive and negative outputs of two times a posi- tive input voltage. For applications where PC board space is at a premium, the MAX681, with its Capacitors internal to the package, offers the smallest footprint. The simple circuit shown in Figure 3 performs the same function using the MAX680 with external capacitors C1 and C8 for the positive pump and G2 and C4 for the negative pump. In most applications, all four capacitors are low-cost, 10UF or 22uF polarized electrolytics. When using the MAX680 for low-current applications, 1HF can be used for C1 and C2 charge-pump capaci- tors, and 4.7uF for C3 and C4 reservoir capacitors. C1 and G3 must be rated at 6V or greater, and C2 and C4 must be rated at 12V or greater. C1 I MAXIM 22yF * MAX6OO Lt. uk .. OUT 2 7 + C2+ Cit C3 oth | | aa 22uF TC uw 3 C2. Yoo 8 Yoo IN 4 5 V- GND ano Figure 3. Positive and Negative Converter L89XVN/089XVWMAX680/MAX681 +5V to +10V Voltage Converters + 22uF MAXIM { MAX680 8 C1- Vt 2 C2+ C1+ u aL 22uF L_stov. Yoo 8 4 Y- GND a 2ouF 22uF J MAAXLAN { MAX680 8 C1- V+ V+ OUT 2 7 + +L Cat t+ 29uF Ts C2. Voc 8 Yoo IN 4 5 Ve GND GND Plo 1 VOUT Figure 4. Paralleling MAX680s For Lower Source Resistance The MAX680/MAX681 are not voltage regulators: the output source resistance of either charge pump is approximately 150Q at room temperature with Vcc at 5V. Under light load with an input Vcc of 5V, V+ will approach +10V and V- will be at -10V. However both, V+ and V- will droop toward GND as the current drawn from either V+ or V- increases, since the negative con- verter draws its power from the positive converters out put. To predict output voltages, treat the chips as two separate converters and analyze them separately. First, the droop of the negative supply (VDROP-) equals the current drawn from V- - (IL-) times the source resistance of the negative converter (RS-): VDROP- = IL- x RS- Likewise, the positive supply droop (VDROP+) equals the current drawn from the positive supply (IL+) times the positive converters source resistance (RS+), except that the current drawn from the positive supply is the sum of the current drawn by the load on the posi- tive supply (IL+) plus the current drawn by the negative converter (IL-}: (VDROP+) = IL+ x BS+ = (IL+ + IL-) x RS+ The positive output voltage will be: V+ = 2VCc VDROP+ The negative output voltage will be: V- = (V+ - VDROP) = - (2Vcc - VDROP + - VDROP-} The positive and negative charge pumps are tested and specified separately to provide the separate values of output source resistance for use in the above formu- las. When the positive charge pump is tested, the neg- ative charge pump is unloaded. When the negative charge pump is tested, the positive supply V+ is from an external source, isolating the negative charge pump. Calculate the ripple voltage on either output by noting that the current drawn from the output is supplied by the reservoir capacitor alone during one half-cycle of the clock. This results in a ripple of: VAIPPLE = YelOUT (1/fpumP)(1/ CR) For the nominal fPumMP of 8kHz with 10yF reservoir capacitors, the ripple will be 30mV with IouUT at 5mA. Remember that in most applications, the positive charge pumps lout is the load current plus the current taken by the negative charge pump. MA AXLAN+5V to +10V Voltage Converters Paralleling Devices Paralleling multiple MAX680/MAX681s reduces the out- put resistance of both the positive and negative con- verters. The effective output resistance is the output resistance of a single device divided by the number of devices. As Figure 4 shows, each MAX680 requires separate pump capacitors C1 and C2, but all can share a single set of reservoir capacitors. t5V Regulated Supplies from a Single 3V Battery Figure 5 shows a complete +5V power supply using cne 3V battery. The MAX680/MAX681 provide +6V at V+, which is regulated to +5V by the MAX666, and -6V, which is regulated to -5V by the MAX664. The MAX666 and MAX664 are pretrimmed at wafer sort and require no external setting resistors, minimizing part count. The combined quiescent current of the MAX680/MAX68&1, MAX668, and MAX664 is less than 500uA, while the out put current capability is 5mA. The MAX680/MAX68 1 input can vary from 3V to 6Y without affecting regulation appreciably. With higher input voltage, more current can be drawn from the MAX680/MAX681 outputs. With 5V at Vcc, 10mA can be drawn from both regulated outputs simultaneously. Assuming 1500 source resistance for both converters, with (IL+ + IL-} = 20mA, the positive charge pump will droop 8V, providing +7V for the nega- tive charge pump. The negative charge pump will droop another 1.8V due to its 10mA load, leaving -5.5V at V- sufficient to maintain regulation for the MAX664 al this current. Te LOW-BATTERY WARNING AT 3.5 LBO I 2MQ. 100puF + Veo + MAAXLAN sv T04av a3 + Cie MAX880 100uF Vt 1.2M0 LBI SENSE AAAXLIA MAX666 +12V TO +6V TT VIN VOUT 45V GND SDN YSET O.4uF * C1- + Gat 100MF Pr y. o C2. GND 100uF [ l 10pF | @No O41 pF ~ GND SDN Veer + 10uF =~ ANAXLIAA MAX6G4 Vin -12V TO -6 VOuTI sever -+}+}-> SENSE Figure 5. Reguiated +5V and -5V from a Single Battery MA AXLIA L89XVN/089XVWMAX680/MAX681 +5V to +10V Voltage Converters Chip Topography 116" (2.95mm} (183mm) Package Information pia INCHES MILLIMETERS MIN | MAX | MIN | MAX A | o.053 | oos9 | 1.35 | 1.75 _ D - At | 0.004 | aoto | o40 | 0.25 | 0-8" B | 0.014 | oo19 | 025 | 049 | ' A ' f. c | 0007 | oot0 | o19 | 025 / L \ E | 0450 | 0157 | 3.80 | 4.00 A A Cae eine te 4 e 0.050 1.27 ele mt em H | 0.228 | 0.244 | 5.80 | 6.20 B c L L | oie | 0.050 | o40 | 1.27 HB A//B AE INCHES MILLIMETERS ' Narrow SO DIM PINS Tin [MAX | MIN | MAX SMALL-OUTLINE Dp | 8 [0189 /0.197 | 4.80 | 5.00 id H PACK AGE DB 14 | 0.337 (0.344 | 8.55 | 8.75 . bp | 16 | 0.386 |0.394 | 9.80 | 10.00 (0.150 in.) 21-0041A Maxim cannot assume responsibility for use of any circuliry other than circuitry entirely embodied in a Maxim product. No circuil 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 1989 Maxim Integrated Products Printed USA AAAXLAA js a registered trademark of Maxim Integrated Products.