The 7660 is a negative voltage converter IC that converts positive voltage to negative voltage, and generating a negative rail 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 circuit for this chip is very simple and requires just two electrolytic capacitors of 10 µF value, making it ideal when a negative DC voltage is required.
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 of +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, however on the rest, this pin is not usually used.
Here is an example positive to negative converter circuit that will work for any voltage between +1.5 V and +10 V, to produce a corresponding negative voltage. These chips are usually used to 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, whilst the voltage conversion efficiency is approximately 97 %. As well as the standard DIP package, it is available in an SO-8 package.
|Switched Capacitor Voltage Converter
|High Frequency DC-DC Voltage Converter
|CMOS Switched-Capacitor Voltage Converter
|Super Voltage Converter