Circuit Schematic learn

How to Build a Positive input Negative output Charge pump Circuit Diagram. A simple means of generating a low-power voltage supply of opposite polarity from the main supply. Self oscillating driver produces pulses at a repetition frequency of 100 kHz. 

When the VMOS device is off, capacitor C is charged to the positive supply. When the VMOS transistor switches on, C delivers a negative voltage through the series diode to the output. The zener serves as a dissipative regulator.

There are some applications, such as double-ended sensors and audio amplifiers that require a negative voltage for operation. With limited space on today’s system boards, creating a dedicated negative supply rail would add to the cost and space of the PCB. Hence, it makes sense to generate the required negative voltage from existing positive supply rails in the system.

One such solution using a traditional synchronous step-down regulator is provided by Texas Instruments in an application note entitled “Creating an Inverting Power Supply Using a Synchronous Step-Down Regulator”1. It shows you how to generate a negative voltage from a positive input voltage to the synchronous buck regulator.