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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 (S—H —D —N – ) 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

Features

♦ 8-Pin, 1.11mm High µMAX Package

♦ Invert or Double the Input Supply Voltage

♦ Three Selectable Switching Frequencies

♦ High Frequency Reduces Capacitor Size

♦ 87% Efficiency at 50mA

♦ 200µA Quiescent Current (MAX860)

♦ 1µA Shutdown Supply Current

♦ 600mV Voltage Drop at 50mA Load

♦ 12Ω Output Resistance

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VDD to GND or GND to OUT)...................+6.0V

Input Voltage Range (LV, FC, SHDN ) ...................(OUT - 0.3V) to (VDD + 0.3V)

Continuous Output Current (OUT, VDD) .............................60mA

Output Short-Circuit to GND (Note 1)...................................1sec

Continuous Power Dissipation (TA = +70°C)

SO (derate 5.88mW/°C above +70°C).........................471mW

µMAX (derate 4.10mW/°C above +70°C) ....................330mW

CERDIP (derate 8.00mW/°C above +70°C).................640mW

Operating Temperature Ranges

MAX86_I_A ......................................................-25°C to +85°C

MAX86_ESA.....................................................-40°C to +85°C

MAX86_MJA ..................................................-55°C to +125°C

Storage Temperature Range .............................-65°C to +160°C

Lead Temperature (soldering, 10sec) .............................+300°C

Note 1: 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.

Typical Operating Circuit

Pin Configuration