Microcontroller chip with integrated LCD control module and switched capacitor driver circuit
US5861861A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1996 |
| Grant date | Jan 19, 1999 |
| Priority date | — |
| Expiry date | Jun 28, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/001
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for providing multiple of discrete voltage levels to drive a liquid crystal display (LCD) from an LCD module on board a microcontroller chip includes a charge pump with a switched-capacitor that develops the discrete voltages as multiples of the value of a base voltage that remains substantially without change irrespective of change in the supply voltage. A switched-capacitor charging circuit selectively charges a capacitor to produce successive additive charges individually retrievable from the capacitor. An LCD drive selectively transmits the discrete voltage levels to activate the LCD according to status of an external system under the control of the microcontroller. Voltage losses that may occur during the switched-capacitor charging are compensated to maintain the levels of the discrete voltages free of decay. Compensation is achieved by overcharging the capacitor by an amount substantially equivalent to the amount of voltage loss on the capacitor, using active feedback obtained from monitoring the charge on the capacitor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.