Design Alternatives to the TC682 for Perfoming Inverting Voltage Doubler Functions (TC682, TCM828/9, TC1219/20, TC1142)
Creating a negative DC bias voltage from a positive DC supply often isrequiredinbattery-poweredportablehandheldinstruments that use a Liquid Crystal Display (LCD). Many LCDs require a relatively large negative bias on the order of ?10V; and since many portable systems (such as cellular subscriber units) often have a regulated +5V DC bias available, the critical design task involves converting this supply voltage to a negative DC bias for the LCD. This application note discusses the advantages and disadvan-tages of several alternatives for implementing the ?10V bias required by the LCD.
Liquid Crystal Display (LCD), regulated +5V DC bias, TCM828. TC682, a regulating DC/DC boost converter, single-cell Li-Ion battery.