MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters _______________General Description The MAX860/MAX861 charge-pump voltage converters invert input voltages ranging from +1.5V to +5.5V, or double input voltages ranging from +2.5V to +5.5V. Because of their high switching frequencies, these devices use only two small, low-cost capacitors. Their 50mA output makes switching regulators unnecessary, eliminating inductors and their associated cost, size, and EMI. Greater than 90% efficiency over most of the load-current range, combined with a typical operating current of only 200µA (MAX860), provides ideal performance for both battery-powered and board-level voltage-conversion applications. A frequency-control (FC) pin provides three switchingfrequencies to optimize capacitor size and quiescent current and to prevent interference with sensitive circuitry. Each device has a unique ———– set of three available frequencies. A shutdown (SHDN) pin reduces current consumption to less than 1µA. The MAX860/MAX861 are suitable for use in applications where the ICL7660 and MAX660's switching frequencies are too low. The MAX860/MAX861 are available in 8-pin µMAX® and SO packages. ________________________Applications Portable Computers Medical Instruments Interface Power Supplies Hand-Held Instruments Operational-Amplifier Power Supplies __________Typical Operating Circuit 1 2 3 C1 10μF 4 FC INPUT VOLTAGE +1.5V TO +5.5V 8 MAX860 MAX861 VDD C1+ SHDN GND LV C1- OUT 7 6 5 INVERTED NEGATIVE OUTPUT 10μF C2 ____________________________Features o 8-Pin, 1.11mm High µMAX Package o Invert or Double the Input Supply Voltage o Three Selectable Switching Frequencies o High Frequency Reduces Capacitor Size o 87% Efficiency at 50mA o 200µA Quiescent Current (MAX860) o 1µA Shutdown Supply Current o 600mV Voltage Drop at 50mA Load o 12Ω Output Resistance ______________Ordering Information PART TEMP RANGE PIN-PACKAGE MAX860ISA -25°C to +85°C 8 SO MAX860IUA -25°C to +85°C 8 µMAX MAX860C/D 0°C to +70°C Dice* MAX860ESA -40°C to +85°C 8 SO MAX860MJA -55°C to +125°C 8 CERDIP† MAX860MSA/PR3 -55°C to +125°C 8 SO MAX861ISA -25°C to +85°C 8 SO MAX861IUA -25°C to +85°C 8 µMAX MAX861C/D 0°C to +70°C Dice* MAX861ESA -40°C to +85°C 8 SO MAX861MJA -55°C to +125°C 8 CERDIP† *Dice are tested at TA = +25°C, DC parameters only. †Contact factory for availability. __________________Pin Configuration TOP VIEW VOLTAGE INVERTER INPUT VOLTAGE +2.5V TO +5.5V + 1 2 3 C1 10μF 4 FC MAX860 VDD MAX861 C1+ SHDN GND LV C1- OUT 8 7 6 DOUBLED POSITIVE OUTPUT 10μF C2 8 VDD 7 SHDN GND 3 6 LV C1- 4 5 OUT FC 1 C1+ 2 MAX860 MAX861 5 POSITIVE VOLTAGE DOUBLER SO/μMAX µMAX is a registered trademark of Maxim Integrated Products, Inc. For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-0239; Rev 3; 8/13 MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters ABSOLUTE MAXIMUM RATINGS Supply Voltage (VDD to GND or GND to OUT) ...................+6.0V –———– Input Voltage Range (LV, FC, S H D N ) ...................(OUT - 0.3V) to (VDD + 0.3V) Continuous Output Current (OUT, VDD) .............................60mA Output Short-Circuit to GND (Note 1).......................................1s Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) .........................471mW µMAX (derate 4.2mW/°C above +70°C) ......................362mW CERDIP (derate 8.00mW/°C above +70°C) .................640mW Note 1: Operating Temperature Ranges MAX86_I_A ......................................................-25°C to +85°C MAX86_ESA.....................................................-40°C to +85°C MAX86_M_A ..................................................-55°C to +125°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10s) .................................+300°C Soldering Temperature (reflow) .......................................+240°C OUT may be shorted to GND for 1sec without damage, but shorting OUT to VDD may damage the device and should be avoided. Also, for temperatures above +85°C, OUT must not be shorted to GND or VDD, even instantaneously, or device damage may result. Stresses beyond those listed under “Absolute 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. ELECTRICAL CHARACTERISTICS –———– (Typical Operating Circuit (Inverter), VDD = +5V, SHDN = VDD, FC = LV = GND, C1 = C2 = 10µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Supply Voltage SYMBOL VDD CONDITIONS RL = 1kΩ MAX860I/E MAX860M No-Load Supply Current (Note 3) IDD MAX861M Doubler, LV = OUT 2.5 5.5 FC = VDD = 5V 0.2 FC = VDD = 3V 0.07 FC = GND 0.6 1.0 FC = OUT 1.4 2.5 0.4 FC = GND 1.3 3.3 FC = VDD 0.3 0.4 FC = GND 1.1 2.0 FC = OUT 2.5 5.0 FC = VDD 0.5 FC = GND 2.6 FC = OUT 6.5 50 V mA 100 IOUT ROUT UNITS 0.3 FC = VDD mA VDD = 3V, VOUT more negative than -2.5V 2 MAX 5.5 VDD = 5V, VOUT more negative than -3.75V Output Resistance (Note 4) TYP 1.5 FC = OUT MAX861I/E Output Current MIN Inverter, LV = GND 10 30 IL = 50mA 12 25 IL = 10mA, VDD = 2V 20 35 Ω Maxim Integrated MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters ELECTRICAL CHARACTERISTICS (continued) –———– (Typical Operating Circuit (Inverter), VDD = +5V, SHDN = VDD, FC = LV = GND, C1 = C2 = 10µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MAX860 Switching Frequency (Note 5) fS MAX861 FC Current (from VDD) IFC MIN FC = VDD 3 6 FC = GND 30 50 FC = OUT 80 130 FC = VDD 8 13 FC = GND 60 100 FC = OUT 160 250 FC < 4V MAX860, FC = VDD Power Efficiency (Note 6) MAX861, FC = VDD -2 RL = 2kΩ from VDD to OUT 93 96 RL = 1kΩ from OUT to GND 90 93 RL = 2kΩ from VDD to OUT 93 96 RL = 1kΩ from OUT to GND 88 92 MAX860/MAX861, FC = VDD, IL = 50mA to GND, C1 = C2 = 68µF Voltage-Conversion Efficiency –———– SHDN Threshold VIH 99 LV = GND 1.2 No load, VOUT = -4V Note 4: Note 5: Note 6: -4 µA % % 0.3 Time to Exit Shutdown UNITS kHz 99.9 VIL –———– S H D N < 0.3V Note 3: MAX 87 No load Shutdown Supply Current Note 2: TYP MAX86_I/E 1 MAX86_M 10 500 V µA µs C1 and C2 are low-ESR (<0.2Ω) aluminum electrolytics. Capacitor ESR adds to the circuit’s output resistance. Using capacitors with higher ESR may reduce output voltage and efficiency. MAX860/MAX861 may draw high supply current during startup, up to the minimum operating supply voltage. To guarantee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current. Specified output resistance includes the effect of the 0.2Ω ESR of the test circuit’s capacitors. The switches are driven directly at the oscillator frequency, without any division. At lowest frequencies, using 10µF capacitors gives worse efficiency figures than using the recommended capacitor values in Table 3, due to larger 1 ⁄ (fs x C1) term in ROUT. Maxim Integrated 3 MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters __________________________________________Typical Operating Characteristics (All curves generated using the inverter circuit shown in the Typical Operating Circuits with LV = GND and TA = +25°C, unless otherwise noted. Test results also valid for doubler mode with LV = OUT and TA = +25°C. All capacitor values used are those recommended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is RO in the equation for ROUT shown in the Capacitor Selection section.) 0.4 0.3 VDD = +3.5V 0.2 VDD = +4.5V, +5.0V VDD = +5.5V 0.1 0 10 20 30 -10 ALL FREQUENCIES, LV CONNECTED TO GND (INVERTER) OR OUT (DOUBLER) -12 -14 OUTPUT SOURCE RESISTANCE (RO) vs. TEMPERATURE MAX860 EFFICIENCY vs. LOAD CURRENT MAX860-04 VDD = +3V 12 90 VDD = +1.5V 60 VDD = +3V 50 VDD = +5V 40 0 0 MAX860-03 INVERTER, LV = GND (VDD > 3V) 200 1 0.1 100 10 0 1 2 3 4 5 6 LOAD CURRENT (mA) SUPPLY VOLTAGE (V) MAX861 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX860 OUTPUT CURRENT vs. CAPACITANCE HIGH-FREQUENCY MODE MAX860 OUTPUT CURRENT vs. CAPACITANC MEDIUM-FREQUENCY MODE 400 OUTPUT CURRENT (mA) DOUBLER, LV = OUT 60 300 INVERTER, LV = GND 200 100 fOSC = 130kHz FC = OUT LV = GND INVERTER MODE 50 VIN = +4.5V, VOUT = -3.5V VIN = +4.5V, VOUT = -4V 40 30 VIN = +3V, VOUT = -2.4V 20 VIN = +3V, VOUT = -2.7V 10 1 2 3 4 SUPPLY VOLTAGE (V) 5 6 70 60 fOSC = 50kHz FC = GND LV = GND INVERTER MODE VIN = +4.5V, VOUT = -3.5V 50 40 VIN = +3V, VOUT = -2.4V 30 VIN = +4.5V, VOUT = -4V 20 VIN = +3V, VOUT = -2.7V 10 0 0 0 80 OUTPUT CURRENT (mA) 70 MAX860-07 FC = VDD MAX860-09 TEMPERATURE (°C) 500 0 300 0 0.01 20 40 60 80 100 120 140 DOUBLER, LV = OUT 100 INVERTER FC = VDD 10 5 4 FC = VDD 400 70 3 2 500 20 4 ALL FREQUENCIES 1 MAX860 SUPPLY CURRENT vs. SUPPLY VOLTAGE 30 VDD = +5V -60 -40 -20 0 6 4 0 SUPPLY CURRENT (μA) VDD = +1.5V 8 8 2 80 16 10 SUPPLY VOLTAGE (V) 100 24 20 12 0 SUPPLY VOLTAGE (V) 28 14 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 EFFICIENCY (%) OUTPUT SOURCE RESISTANCE (Ω) -8 LOAD CURRENT (mA) ALL FREQUENCIES SUPPLY CURRENT (μA) -6 50 40 32 4 -4 MAX860-05 0 -2 18 16 MAX860-06 0.5 20 MAX860-08 VOUT DROP (V) 0.6 VDD = +2.5V 0 OUTPUT SOURCE RESISTANCE (Ω) VDD = +1.5V 2 OUTPUT SOURCE RESISTANCE (RO) vs. SUPPLY VOLTAGE MAX860-02 ALL FREQUENCIES 0.7 PERCENTAGE FREQUENCY CHANGE (%) (FROM FREQUENCY MEASURED WITH VDD = +5V) 0.8 OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE MAX860-01 OUTPUT VOLTAGE DROP FROM SUPPLY VOLTAGE vs. LOAD CURRENT 0.33 1 2.2 4.7 CAPACITANCE (μF) 10 22 0.33 1 2.2 4.7 10 22 CAPACITANCE (μF) Maxim Integrated MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters ____________________________Typical Operating Characteristics (continued) (All curves generated using the inverter circuit shown in the Typical Operating Circuits with LV = GND and TA = +25°C, unless otherwise noted. Test results also valid for doubler mode with LV = OUT and TA = +25°C. All capacitor values used are those recommended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is RO in the equation for ROUT shown in the Capacitor Selection section.) 70 fOSC = 250kHz FC = OUT LV = GND INVERTER MODE 60 80 VIN = +4.5V, VOUT = -3.5V 50 VIN = +4.5V, VOUT = -4V 40 30 VIN = +3V, VOUT = -2.4V 20 60 0 VIN = +4.5V, VOUT = -3.5V 50 VIN = +3V, VOUT = -2.4V 40 VIN = +4.5V, VOUT = -4V 30 20 VIN = +3V, VOUT = -2.7V 10 VIN = +3V, VOUT = -2.7V 10 fOSC = 100kHz FC = GND LV = GND INVERTER MODE 70 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 80 MAX860-10 90 MAX861 OUTPUT CURRENT vs. CAPACITANCE MEDIUM-FREQUENCY MODE MAX860-11 MAX861 OUTPUT CURRENT vs. CAPACITANCE HIGH-FREQUENCY MODE 0 0.33 1 2.2 4.7 10 0.33 22 CAPACITANCE (μF) 1 2.2 4.7 10 22 CAPACITANCE (μF) ______________________________________________________________Pin Description FUNCTION PIN NAME INVERTER DOUBLER Frequency Control, see Table 1 Frequency Control, see Table 1 1 FC 2 C1+ Flying-Capacitor Positive Terminal Flying-Capacitor Positive Terminal 3 GND Ground Positive Input Supply 4 C1- Flying-Capacitor Negative Terminal Flying-Capacitor Negative Terminal 5 OUT Negative Output Ground 6 LV Low-Voltage-Operation Input. Connect to GND. Low-Voltage-Operation Input. Connect to OUT. 7 –———– SHDN Active-Low Shutdown Input. Connect to VDD if not used. Connect to GND to disable the charge pump. Active-Low Shutdown Input. Connect to GND pin if not used. Connect to OUT to disable the charge pump. 8 VDD Positive Input Supply Doubled Positive Output Maxim Integrated 5 MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters _______________Detailed Description The MAX860/MAX861 capacitive charge pumps either invert or double the voltage applied to their inputs. For highest performance, use low equivalent series resistance (ESR) capacitors. See the Capacitor Selection section for more details. The frequency-control (FC) pin allows you to choose one of three switching frequencies; these three selectable frequencies are different for each device. When shut down, MAX860/MAX861 current consumption reduces to less than 1µA. Common Applications Voltage Inverter The most common application for these devices is a charge-pump voltage inverter (see Typical Operating Circuits). This application requires only two external components—capacitors C1 and C2—plus a bypass capacitor if necessary (see Bypass Capacitor section). Refer to the Capacitor Selection section for suggested capacitor types and values. Even though the MAX860/MAX861’s output is not actively regulated, it is fairly insensitive to load-current changes. A circuit output source resistance of 12Ω (calculated using the formula given in the Capacitor Selection section) means that, with a +5V input, the output voltage is -5V under no load and decreases to -4.4V with a 50mA load. The MAX860/MAX861 output source resistance (used to calculate the circuit output source resistance) vs. temperature and supply voltage are shown in the Typical Operating Characteristics graphs. Calculate the output ripple voltage using the formula given in the Capacitor Selection section. Positive Voltage Doubler The MAX860/MAX861 can also operate as positive voltage doublers (see Typical Operating Circuits ). This application requires only two external components, capacitors C1 and C2. The no-load output is twice the input voltage. The electrical specifications in the doubler mode are very similar to those of the inverter mode except for the Supply Voltage Range (see Electrical Characteristics table) and No-Load Supply Current (see graph in Typical Operating Characteristics). The circuit output source resistance and output ripple voltage are calculated using the formulas in the Capacitor Selection section. Active-Low Shutdown Input –———– When driven low, the SHDN input shuts down the –——— – device. In inverter mode, connect SH–— D— N—–to VDD if it is not used. In doubler mode, connect SHDN to GND if it 6 is not used. When the device is shut down, all active circuitry is turned off. In the inverting configuration, loads connected from OUT to GND are not powered in shutdown mode. However, a reverse-current path exists through two diodes between OUT and GND; therefore, loads connected from VDD to OUT draw current from the input supply. In the doubling configuration, loads connected from the VDD pin to the GND pin are not powered in shutdown mode. Loads connected from the VDD pin to the OUT pin draw current from the input supply through a path similar to that of the inverting configuration (described above). Frequency Control Charge-pump frequency for both devices can be set to one of three values. Each device has a unique set of three available frequencies, as indicated in Table 1. The oscillator and charge-pump frequencies are the same (i.e., the charge-pump frequency is not half the oscillator frequency, as it is on the MAX660, MAX665, and ICL7660). Table 1. Nominal Switching Frequencies* FREQUENCY (kHz) FC CONNECTION MAX860 MAX861 FC = VDD or open 6 13 FC = GND 50 100 FC = OUT 130 250 *See the Electrical Characteristics for detailed switchingfrequency specifications. A higher switching frequency minimizes capacitor size for the same performance and increases the supply current (Table 2). The lowest fundamental frequency of the switching noise is equal to the minimum specified switching frequency (e.g., 3kHz for the MAX860 with FC open). The spectrum of noise frequencies extends above this value because of harmonics in the switching waveform. To get best noise performance, choose the device and FC connection to select a minimum switching frequency that lies above your sensitive bandwidth. Low-Voltage-Operation Input LV should be connected to GND for inverting operation. To enhance compatibility with the MAX660, MAX665, and ICL7660, you may float LV if the input voltage exceeds 3V. In doubling mode, LV must be connected to OUT for all input voltages. Maxim Integrated MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters Table 2. Switching-Frequency Trade-Offs LOWER FREQUENCY Larger HIGHER FREQUENCY Smaller C1, C2 Values Larger Smaller Supply Current Smaller Larger ATTRIBUTE Output Ripple __________Applications Information Capacitor Selection The MAX860/MAX861 are tested using 10µF capacitors for both C1 and C2, although smaller or larger values can be used (Table 3). Smaller C1 values increase the output resistance; larger values reduce the output resistance. Above a certain point, increasing the capacitance of C1 has a negligible effect (because the output resistance becomes dominated by the internal switch resistance and the capacitor ESR). Low-ESR capacitors provide the lowest output resistance and ripple voltage. The output resistance of the entire circuit (inverter or doubler) is approximately: ROUT = RO + 4 x ESRC1 + ESRC2 + 1 / (fS x C1) where R O (the effective resistance of the MAX860/ MAX861’s internal switches) is approximately 8Ω and fS is the switching frequency. ROUT is typically 12Ω when using capacitors with 0.2Ω ESR and fS, C1, and C2 values suggested in Table 3. When C1 and C2 are so large (or the switching frequency is so high) that the internal switch resistance dominates the output resistance, estimate the output resistance as follows: ROUT = RO + 4 x ESRC1 + ESRC2 A typical design procedure is as follows: 1) Choose C1 and C2 to be the same, for convenience. 2) Select fS: a) If you want to avoid a specific noise frequency, choose fS appropriately. b) If you want to minimize capacitor cost and size, choose a high fS. c) If you want to minimize current consumption, choose a low fS. 3) Choose a capacitor based on Table 3, although higher or lower values can be used to optimize performance. Table 4 lists manufacturers who provide low-ESR capacitors. Table 3. Suggested Capacitor Values* NOMINAL FREQUENCY (kHz) C1, C2 (μF) 6 68 13 47 50 10 100 4.7 130 4.7 250 2.2 *In addition to Table 3, four graphs in the Typical Operating Characteristics section show typical output current for C1 and C2 capacitances ranging from 0.33µF to 22µF. Output current is plotted for inputs of 4.5V (5V - 10%) and 3.0V (3.3V - 10%), and also for 10% and 20% output droop from the ideal -VIN value. Table 4. Low-ESR Capacitor Manufacturers MANUFACTURER–Series PHONE FAX COMMENTS AVX TPS Series (803) 946-0629 (803) 626-3123 Low-ESR tantalum, SMT AVX TAG Series (803) 946-0629 (803) 626-3123 Low-cost tantalum, SMT Matsuo 267 Series (714) 969-2491 (714) 960-6492 Low-cost tantalum, SMT Sprague 595 Series (603) 224-1961 (613) 224-1430 Low-ESR tantalum, SMT Sanyo MV-GX Series (619) 661-6835 (619) 661-1055 Aluminum electrolytic, through hole Sanyo CV-GX Series (619) 661-6835 (619) 661-1055 Aluminum electrolytic, SMT Nichicon PL Series (847) 843-7500 (847) 843-2798 Aluminum electrolytic, through hole United Chemicon (Marcon) (847) 696-2000 (847) 696-9278 Ceramic SMT TDK (847) 390-4461 (847) 390-4405 Ceramic SMT Maxim Integrated 7 MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters Flying Capacitor, C1 Increasing the size of the flying capacitor reduces the output resistance. Output Capacitor, C2 Increasing the size of the output capacitor reduces the output ripple voltage. Decreasing its ESR reduces both output resistance and ripple. Smaller capacitance values can be used if one of the higher switching frequencies is selected, if less than the maximum rated output current (50mA) is required, or if higher ripple can be tolerated. The following equation for peak-to-peak ripple applies to both the inverter and doubler circuits. IOUT VRIPPLE = ———————— + 2 x IOUT x ESRC2 2 x fS x C2 Bypass Capacitor Bypass the incoming supply to reduce its AC impedance and the impact of the MAX860/MAX861’s switching noise. The recommended bypassing depends on the circuit configuration and where the load is connected. When the inverter is loaded from OUT to GND or the doubler is loaded from VDD to GND, current from the supply switches between 2 x IOUT and zero. Therefore, use a large bypass capacitor (e.g., equal to the value of C1) if the supply has a high AC impedance. When the inverter and doubler are loaded from VDD to OUT, the circuit draws 2 x IOUT constantly, except for short switching spikes. A 0.1µF bypass capacitor is sufficient. Cascading Devices Two devices can be cascaded to produce an even larger negative voltage, as shown in Figure 1. The unloaded output voltage is nominally -2 x VIN, but this is reduced slightly by the output resistance of the first device multiplied by the quiescent current of the second. The output resistance of the complete circuit is approximately five times the output resistance of a single MAX860/MAX861. Three or more devices can be cascaded in this way, but output resistance rises dramatically, and a better solution is offered by inductive switching regulators (such as the MAX755, MAX759, MAX764, or MAX774). Connect LV as with a standard inverter circuit (see Pin Description). The maximum load current and startup current of nth cascaded circuit must not exceed the maximum output current capability of (n-1)th circuit to ensure proper startup. Paralleling Devices Paralleling multiple MAX860s or MAX861s reduces the output resistance. As illustrated in Figure 2, each device requires its own pump capacitor (C1), but the reservoir capacitor (C2) serves all devices. C2’s value should be increased by a factor of n, where n is the number of devices. Figure 2 shows the equation for calculating output resistance. An alternative solution is to use the MAX660 or MAX665, which are capable of supplying up to 100mA of load current. Connect LV as with a standard inverter circuit (see Pin Description). Combined Doubler/Inverter In the circuit of Figure 3, capacitors C1 and C2 form the inverter, 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 towards GND. Make ROUT OF SINGLE DEVICE ROUT = NUMBER OF DEVICES … 8 2 C1 3 4 MAX860 MAX861 “1” +VIN +VIN 8 2 7 3 C1 5 MAX860 MAX861 “n” 8 7 5 4 … 2 VOUT C1 3 4 C2 C2 … MAX860 MAX861 “1” 8 2 7 3 C1 5 7 MAX860 MAX861 “n” 5 4 VOUT … VOUT = -VIN C2 VOUT = -nVIN Figure 1. Cascading MAX860s or MAX861s to Increase Output Voltage 8 Figure 2. Paralleling MAX860s or MAX861s to Reduce Output Resistance Maxim Integrated MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters Table 5. Product Selection Guide +VIN 8 2 C1 3 MAX860 MAX861 4 7 PART NUMBER OUTPUT CURRENT (mA) MAX660 100 6.5 5/40 MAX665 100 6.5 5/40 MAX860 50 12 6/50/130 MAX861 50 12 13/100/250 ICL7660 10 55 5 D1, D2 = 1N4148 D1 5 OUTPUT SWITCHING RESISTANCE FREQUENCY (Ω) (kHz) VOUT = -VIN C2 D2 C3 C4 VOUT = (2VIN) (VFD1) - (VFD2) Figure 3. Combined Doubler and Inverter sure the sum of the currents drawn from the two outputs does not exceed 60mA. Connect LV as with a standard inverter circuit (see Pin Description). Compatibility with MAX660/MAX665/ICL7660 The MAX860/MAX861 can be used in sockets designed for the MAX660, MAX665, and ICL7660 with a minimum of one wiring change. This section gives advice on installing a MAX860/MAX861 into a socket designed for one of the earlier devices. The MAX660, MAX665, and ICL7660 have an OSC pin –——— – instead of SHDN. MAX660, MAX665, and ICL7660 normal operation is with OSC floating (although –———–OSC can be overdriven). If OSC is floating, pin 7 (SHDN ) should the be jumpered to VDD to enable –—— —– MAX860/MAX861 permanently. Do not leave SHDN on the MAX860/ MAX861 floating. The MAX860/MAX861 operate with FC either floating or connected to V DD , OUT, or GND; each connection defines the oscillator frequency. Thus, any of the normal MAX660, MAX665, or ICL7660 connections to pin 1 will work with the MAX860/MAX861, without modifications. Changes to the FC connection are only required if you want to adjust the operating frequency. Maxim Integrated ___________________Chip Topography V DD FC 0.084" (2.13mm) C1+ GND SHDN C1- LV OUT 0.058" (1.47mm) PROCESS: BiCMOS SUBSTRATE CONNECTED TO VDD 9 MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters Package Information For the latest package outline information and land patterns (footprints), 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. 10 PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 SO S8-4 21-0041 90-0096 8 CDIP J8-2 21-0045 — 8 µMAX U8-1 21-0036 90-0092 Maxim Integrated MAX860/MAX861 50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters Revision History PAGES CHANGED REVISION NUMBER REVISION DATE 0 7/94 Initial release 2 4/03 Updated Electrical Characteristics and Cascading Devices section. 3, 8 3 8/13 Added MAX860MSA/PR3 to data sheet and revised Absolute Maximum Ratings. 1, 2 DESCRIPTION — 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. 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