MAX1044 Maxim Integrated Products, MAX1044 Datasheet
MAX1044
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MAX1044 Summary of contents
Page 1
... ICL7660 and LTC1044. Operation is guaranteed from 1.5V to 10V with no external diode over the full temperature range. They deliver 10mA with a 0.5V output drop. The MAX1044 has a BOOST pin that raises the oscillator frequency above the audio band and reduces external capacitor size requirements ...
Page 2
... A Note 1: The Maxim ICL7660 and MAX1044 can operate without an external output diode over the full temperature and voltage ranges. The Maxim ICL7660 can also be used with an external output diode in series with pin 5 (cathode at V replacing the Intersil ICL7660. Tests are performed without diode in circuit. ...
Page 3
... BOOST = OPEN 40 SUPPLY CURRENT 10V OPEN LOAD CURRENT (mA) OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE 100,000 10,000 FROM TOP TO BOTTOM AT 5V MAX1044, BOOST = V GND 1000 MAX1044, BOOST = V OPEN ICL7660 GND ICL7660 OPEN MAX1044, BOOST = OPEN GND MAX1044, BOOST = OPEN OPEN 100 SUPPLY VOLTAGE (V) 3 ...
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... TEMPERATURE (°C) QUIESCENT CURRENT vs. SUPPLY VOLTAGE 2000 1000 A B 100 MAX1044, BOOST = V GND B: MAX1044, BOOST = V OPEN C: ICL7660 and MAX1044 with 1 BOOST = OPEN GND; ABOVE 5V, MAX1044 ONLY D: ICL7660 and MAX1044 with BOOST = OPEN OPEN 0 SUPPLY VOLTAGE (V) OUTPUT RESISTANCE vs. OSCILLATOR FREQUENCY 1000 ...
Page 5
... V than - (V+) since the switches S1–S4 have resistance OUT and the load drains charge from C2. Additional qualities of the MAX1044/ICL7660 can be understood by using a switched-capacitor circuit model. Switching the bucket capacitor, C1, between the input and output of the circuit synthesizes a resis- tance (Figures 3a and 3b.) When the switch in Figure the left position, capacitor C1 charges to V+ ...
Page 6
... For many applications, only two external capacitors are needed. The type of capacitor used is not critical. Proper Use of the Low-Voltage (LV) Pin R LOAD Figure 4 shows an internal voltage regulator inside the MAX1044/ICL7660. Use the LV pin to bypass this regulator, in order to improve low-voltage performance 1M V BOOST OUT pin 1 ...
Page 7
... MAX1044 and a typical value of 10kHz for the ICL7660 are specified specific oscillator frequency is required, use an external oscillator to drive the OSC pin. Increasing Oscillator Frequency Using the BOOST Pin For the MAX1044, connecting the BOOST pin to the V+ pin raises the oscillator frequency by a factor of about 6. _______________________________________________________________________________________ V+ V -(V+) ...
Page 8
... The output ripple and output drop increase under heavy loads. If necessary, the MAX1044/ICL7660 out- put impedance can be reduced by paralleling devices, increasing the capacitance of C1 and C2, or connect- ing the MAX1044’s BOOST pin increase the oscillator frequency. Inrush Current and EMI Considerations During start-up, pump capacitors C1 and C2 must be charged ...
Page 9
... GND (pin 3). Adding a diode in parallel with C2, with the anode connected LV, will prevent this condition. ________________Application Circuits Figure 8 shows a negative voltage converter, the most popular application of the MAX1044/ICL7660. Only two external capacitors are needed. A third power-supply bypass capacitor is recommended (0.1µF to 10µ ...
Page 10
... Three or more devices can be cascaded in this way, but output impedance rises dramatically. For example, the output resistance of two cascaded MAX1044s is approximately five times the output resis- tance of a single voltage converter. A better solution may be an inductive switching regulator, such as the MAX755, MAX759, MAX764, or MAX774 ...
Page 11
... The equation for calculating output resistance is: R OUT R OUT Figures 14a–14c illustrate three ways of adding shut- down capability to the MAX1044/ICL7660. When using these circuits, be aware that the additional capacitive loading on the OSC pin will reduce the oscillator fre- V -(V+) OUT quency ...
Page 12
... Switched-Capacitor Voltage Converters __________________________________________________________Chip Topographies MAX1044 GND CAP+ BOOST CAP- V OUT LV OSC 0.076" (1.930mm) TRANSISTOR COUNT: 72 SUBSTRATE CONNECTED TO V+ ________________________________________________________Package Information 0.127mm 0.004 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied ...