Fairchild Negative Voltage Management with FAN8303 Buck Regulator Data Manual

www.fairchildsemi.com

AN-8023 Negative Voltage Management Using a FAN8303 Buck Regulator

for linear regulators in PC monitor and TV applications. In

Abstract some cases, a non-synchronous buck regulator also can be

utilized for buck-boost circuit to generate negative voltage

FAN8303 is a 2A, 370k Hz monolithic integrated buck

with respect to ground. These applications include audio

regulator with internal power MOSFETs. It is simple to use

amplifier, timing control circuit for LCD panel, and so on.

and needs minimal external components. This application note describes how to generate negative voltage using Figure 1 shows a practical application of an LCD panel; it FAN8303. It introduces application examples and discusses needs negative voltage for contrast control. In this block optimized designs for a buck-boost circuit. diagram, a charge pump is usually adopted due to the simple

design and low cost. However, it has an amount of power Introduction dissipation and poor output voltage regulation relative to input voltage variation. FAN8303 with negative output

Buck regulators are widely used for higher voltage to lower would be a solution to overcome these problems. voltage DC conversion. Likewise, FAN8303 was originally designed for application needing regulated DC voltage, such as set-top box microcontrollers and efficient pre-regulators ow riv er

Charge pump

AV Board 2.5V, 3.3V

LDO So C

TFT LCD Panel

DC/DC (buck)

DDR2 EEPROM

DC/DC (boost)

Column Drivers

P-gamma IC

Figure 1. Example of Timing Control Block

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 7/30/09