Input and output polarity reversal circuit composed of MAX660

The input and output voltage reversal circuit of X660 is shown in the figure. The input voltage is 1.5~5.5 V, and the voltage can be outputted as -1.5~-5.5 V after voltage reversal. When the load current increases, the output voltage will drop. For example, when the load current is 100 mA and the input voltage is 5 V, the output voltage is about -4.35 V. The ripple of the output voltage is related to the load current, the oscillation frequency, the capacity of C2 and the ESR. When the oscillation frequency is 10 kHz, C2 is 150 μF, and the ESR is 0.2 Ω, the ripple voltage is about 90 mV (100 mA current); if C2 is 390 μF, the ripple voltage can be reduced to 45 mV. (a) Positive input and negative output; (b) Negative input and positive output.