The 7660 is a negative voltage converter IC that converts positive voltage to negative voltage. Generating negative output from positive voltage is very easy using this chip. The circuit shown will convert a positive voltage in the range of +1.5 V to +10 V, into a corresponding negative voltage in the same range -1.5 V to -10 V.
The application for this chip is very simple and requires just two electrolytic capacitors of 10-µF value. The circuit is ideal if you need a negative DC voltage.
For example, if the supply voltage Vcc at Pin 8 was +5 V, then the corresponding output on Pin 5 will be -5 V.
The boost function enables a higher switching frequency of the internal oscillator. It is optional and used on applications where noise is a major consideration of the design feature.
Many different manufacturers make this 7660 chip; however, the Intersil brand has a wider input voltage range +1.5 V to +12 V, whilst the rest operate between +1.5 V to +10 V. The Holtek and Intersil brands have a “BOOST” function on Pin 1 whilst on the rest this pin is not used.
Here is an example positive to negative converter circuit. It will work for any voltages between +1.5 V and +10 V, to produce a corresponding negative voltage.
These chips drive low current digital and analogue circuits that require a negative voltage rail.
The IC consumes a very low supply current of around 200 µA, and the power dissipation is typically around 1.4 W. The voltage conversion efficiency is around 97 %. As well as the standard DIP package, it is available in an SO-8 package.
|LMC7660||Switched Capacitor Voltage Converter|
|TC7660H||High Frequency DC-DC Voltage Converter|
|HT7660||CMOS Switched-Capacitor Voltage Converter|
|ICL7660S||Super Voltage Converter|