Document
19-1240; Rev 0; 6/97
Switched-Capacitor Voltage Inverters
_______________General Description
The ultra-small MAX870/MAX871 monolithic, CMOS charge-pump inverters accept input voltages ranging from +1.4V to +5.5V. The MAX870 operates at 125kHz, and the MAX871 operates at 500kHz. Their high efficiency (90%) and low operating current (0.7mA for the MAX870) make these devices ideal for both battery-powered and board-level voltage-conversion applications. Oscillator control circuitry and four power MOSFET switches are included on-chip. A typical MAX870/ MAX871 application is generating a -5V supply from a +5V logic supply to power analog circuitry. Both parts come in a 5-pin SOT23-5 package and can deliver 25mA with a voltage drop of 500mV. For applications requiring more power, the MAX860 delivers up to 50mA with a voltage drop of 600mV, in a space-saving µMAX package.
____________________________Features
o 5-Pin SOT23-5 Package o 99% Voltage Conversion Efficiency o Invert Input Supply Voltage o 0.7mA Quiescent Current (MAX870) o +1.4V to +5.5V Input Voltage Range o Require Only Two Capacitors o 25mA Output Current o Shutdown Control
MAX870/MAX871
______________Ordering Information
PART MAX870C/D MAX870EUK MAX871C/D MAX871EUK TEMP. RANGE 0°C to +70°C -40°C to +85°C 0°C to +70°C -40°C to +85°C PINPACKAGE Dice* 5 SOT23-5 Dice* 5 SOT23-5 SOT TOP MARK — ABZN — ABZO
________________________Applications
Local -5V Supply from 5V Logic Supply Small LCD Panels Cell Phones Medical Instruments Handy-Terminals, PDAs Battery-Operated Equipment
* Dice are tested at TA = +25°C.
__________Typical Operating Circuit
__________________Pin Configuration
5
C1+
IN
2
INPUT SUPPLY VOLTAGE
TOP VIEW
MAX870 MAX871
3 C1OUT 4 1 NEGATIVE OUTPUT VOLTAGE
OUT
1
5
C1+
IN
2
MAX870 MAX871
4 GND
C1-
3
GND
SOT23-5 NEGATIVE VOLTAGE CONVERTER
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Switched-Capacitor Voltage Inverters MAX870/MAX871
ABSOLUTE MAXIMUM RATINGS
IN to GND ..............................................................+6.0V to -0.3V OUT to GND ..........................................................-6.0V to +0.3V C1+ ..............................................................(VIN + 0.3V) to -0.3V C1-............................................................(VOUT - 0.3V) to +0.3V OUT Output Current ...........................................................50mA OUT Short Circuit to GND .............................................Indefinite Continuous Power Dissipation (TA = +70°C) SOT23-5 (derate 7.1mW/°C above +70°C)...................571mW Operating Temperature Range MAX870EUK/MAX871EUK ...............................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C
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
(VIN = +5V, C1 = C2 = 1µF (MAX870), C1 = C2 = 0.33µF (MAX871), TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS Supply Current Minimum Supply Voltage Maximum Supply Voltage Oscillator Frequency Power Efficiency Voltage Conversion Efficiency TA = +25°C RLOAD = 10kΩ RLOAD = 10kΩ TA = +25°C RLOAD = 500kΩ, TA =+25°C RLOAD = ∞, TA =+25°C MAX870 MAX871 MAX870 MAX871 MAX870 MAX871 C1 = C2 = 1µF C1 = C2 = 0.47µF C1 = C2 = 0.33µF MAX871 C1 = C2 = 0.22µF C1 = C2 = 0.1µF TA = 0°C to + 85°C 98 96 81 325 125 500 90 75 99.3 99 20 25 20 25 35 65 50 Ω 50 MAX870 MAX871 TA = +25°C TA = 0°C to + 85°C 1.4 1.5 5.5 169 675 0.7 2.7 1.0 1.0 3.8 mA V V kHz % %
MAX870 Output Resistance (Note 1) IOUT = TA = +25°C 5mA
Note 1: Capacitor contribution is approximately 20% of the output impedance [ESR + 1 / (pump frequency x capacitance)].
ELECTRICAL CHARACTERISTICS
(VIN = +5V, C1 = C2 = 1µF (MAX870), C1 = C2 = 0.33µF (MAX871), TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Supply Current Minimum Supply-Voltage Range Maximum Supply-Voltage Range Oscillator Frequency Output Resistance Voltage Conversion Efficiency MAX870 MAX871 RLOAD = 10kΩ RLOAD = 10kΩ MAX870 MAX871 IOUT = 5mA RLOAD = ∞ MAX870 MAX871 97 95 56 225 1.6 5.5 194 775 65 1.3 4.4 mA V V kHz Ω %
Note 2: All -40°C to +85°C specifications are guaranteed by design. 2 _______________________________________________________________________________________
Switched-Capacitor Voltage Inverters
__________________________________________Typic.