Abstract

Many TFT-LCD panels require negative voltage rail and positive voltage rail to power the amplifiers from the 12-V or 5-V power supply. Generating Negative and Positive Voltage Rail With Boost Converter TLV61048, application note used TLV61048 device and referred to Design for a Discrete Charge Pump, application note to demonstrate an example to generate the negative voltage rail and positive voltage rail. For asynchronous boot converter, the forward diode can help reduce the gap between positive voltage rail and negative voltage rail and for synchronous boost converter, due to MOSFET integration, the forward voltage drop is very low, but it also can use a diode to minimize the gap. But the diode cannot effectively reduce the voltage gap through the full load current range. This application note demonstrates using the resistor to effectively reduce the gap. The application can also design a calculator to simplify the design procedure. The components based on the asynchronous boost converter using the Boost Converter± Quick Calculator available for download from the TPS61377 product folder. Last, the document shows an example using TPS61377 and shows the precaution for the schematic design and layout design.