_______________General Description
The MAX660 monolithic, charge-pump voltage inverterconverts a +1.5V to +5.5V input to a corresponding-1.5V to -5.5V output. Using only two low-costcapacitors, the charge pump’s 100mA output replacesswitching regulators, eliminating inductors and theirassociated cost, size, and EMI. Greater than 90?ficiency over most of its load-current range combinedwith a typical operating current of only 120μA providesideal performance for both battery-powered and board-level voltage conversion applications. The MAX660 canalso double the output voltage of an input power supplyor battery, providing +9.35V at 100mA from a +5Vinput.
A frequency control (FC) pin selects either 10kHz typ or80kHz typ (40kHz min) operation to optimize capacitorsize and quiescent current. The oscillator frequencycan also be adjusted with an external capacitor ordriven with an external clock. The MAX660 is a pin-compatible, high-current upgrade of the ICL7660.
The MAX660 is available in both 8-pin DIP and small-outline packages in commercial, extended, and militarytemperature ranges.
For 50mA applications, consider the MAX860/MAX861pin-compatible devices (also available in ultra-smallμMAX packages).
________________________Applications
Laptop ComputersMedical InstrumentsInterface Power SuppliesHand-Held Instruments
Operational-Amplifier Power Supplies
__________________Pin Configuration
TOP VIEWFC18V+CAP+27OSCGND3MAX6606LVCAP-45OUTDIP/SO___________________________Features
?Small Capacitors
?0.65V Typ Loss at 100mA Load?Low 120μA Operating Current?6.5?Typ Output Impedance
?Guaranteed ROUT< 15?for C1 = C2 = 10μF?Pin-Compatible High-Current ICL7660 Upgrade?
Inverts or Doubles Input Supply Voltage
?Selectable Oscillator Frequency: 10kHz/80kHz?88% Typ Conversion Efficiency at 100mA(ILto GND)
______________Ordering Information
PARTTEMP. RANGEPIN-PACKAGEMAX660CPA0°C to +70°C8 Plastic DIPMAX660CSA0°C to +70°C8 SOMAX660C/D0°C to +70°CDice*
MAX660EPA-40°C to +85°C8 Plastic DIPMAX660ESA-40°C to +85°C8 SO
MAX660MJA
-55°C to +125°C
8 CERDIP
*Contact factory for dice specifications.
_________Typical Operating Circuits
+VIN1.5V TO 5.5V1FCV+82CAP+MAX660OSC7C11μF to 150μF3GNDLV6INVERTEDNEGATIVE4CAP-OUT5VOLTAGEOUTPUTC2VOLTAGE INVERTER1μF to 150μFDOUBLEDPOSITIVEVOLTAGE1FCV+8OUTPUTC12C21μF to 150μFCAP+MAX660OSC71μF to 150μF+VIN3GNDLV62.5V TO 5.5V4CAP-OUT5POSITIVE VOLTAGE DOUBLERMAX660CMOS Monolithic Voltage ConverterMAX660______________Detailed Description
The MAX660 capacitive charge-pump circuit eitherinverts or doubles the input voltage (see TypicalOperating Circuits). For highest performance, loweffective series resistance (ESR) capacitors should beused. See Capacitor Selectionsection for more details.When using the inverting mode with a supply voltageless than 3V, LV must be connected to GND. Thisbypasses the internal regulator circuitry and providesbest performance in low-voltage applications. Whenusing the inverter mode with a supply voltage above3V, LV may be connected to GND or left open. The partis typically operated with LV grounded, but since LVmay be left open, the substitution of the MAX660 for theICL7660 is simplified. LV must be grounded when over-driving OSC (see Changing Oscillator Frequencysec-tion). Connect LV to OUT (for any supply voltage) whenusing the doubling mode.
one-half of the charge-pump cycle. This introduces apeak-to-peak ripple of:
VRIPPLE = IOUT+IOUT(ESRC2)
2(fPUMP) (C2)
For a nominal fPUMPof 5kHz (one-half the nominal10kHz oscillator frequency) and C2 = 150μF with anESR of 0.2?, ripple is approximately 90mV with a100mA load current. If C2 is raised to 390μF, the rippledrops to 45mV.
Positive Voltage Doubler
The MAX660 operates in the voltage-doubling mode asshown in the Typical Operating Circuit.The no-loadoutput is 2 x VIN.
Other Switched-Capacitor Converters
Please refer to Table 1, which shows Maxim’s charge-pump offerings.
__________Applications Information
Negative Voltage Converter
The most common application of the MAX660 is as acharge-pump voltage inverter. The operating circuituses only two external capacitors, C1 and C2 (seeTypical Operating Circuits).
Even though its output is not actively regulated, theMAX660 is very insensitive to load current changes. Atypical output source resistance of 6.5?means thatwith an input of +5V the output voltage is -5V underlight load, and decreases only to -4.35V with a load of100mA. Output source resistance vs. temperature andsupply voltage are shown in the Typical OperatingCharacteristicsgraphs.
Output ripple voltage is calculated by noting the outputcurrent supplied is solely from capacitor C2 during
Changing Oscillator Frequency
Four modes control the MAX660’s clock frequency, aslisted below:FCOpenFC = V+Open orFC = V+Open
OSCOpenOpenExternal CapacitorExternal Clock
Oscillator Frequency10kHz80kHz
See Typical OperatingCharacteristics
External Clock Frequency
When FC and OSC are unconnected (open), the oscil-lator runs at 10kHz typically. When FC is connected toV+, the charge and discharge current at OSC changesfrom 1.0μA to 8.0μA, thus increasing the oscillator
Table 1. Single-Output Charge Pumps
MAX828PackageOp. Current(typ, mA)Output ?(typ)Pump Rate(kHz)Input (V)SOT 23-50.0620121.25 to 5.5MAX829SOT 23-50.1520351.25 to 5.5MAX860SO-8,μMAXMAX861SO-8,μMAXMAX660SO-8MAX1044SO-8,μMAX0.036.551.5 to 10ICL7662SO-80.25125101.5 to 10ICL7660SO-8,μMAX0.0855101.5 to 100.2 at 6kHz,0.3 at 13kHz,0.12 at 5kHz,0.6 at 50kHz,1.1 at 100kHz,1 at 40kHz1.4 at 130kHz2.5 at 250kHz126, 50, 1301.5 to 5.51213, 100, 1501.5 to 5.56.55, 401.5 to 5.5
MEMORY存储芯片MAX660CSA+T中文规格书 - 图文
