DISPLAY DRIVER

Display drivers are used to send and receive data from different interfaces. There are two types of display drivers: software display drivers that use software applications to display outputs of graphic cards and other computer hardware cards, and analog display drivers that are used to display outputs of electrical devices.

Computer hardware graphic card manufacturers offer display drivers for their cards. The software is supplied along with the card and needs to be installed in the computer. These drivers are device-specific and need to be configured to get the best results that the computer hardware configuration allows. They can be downloaded from the manufacturer’s website. In addition, devices like printers, digital cameras, PDAs, keyboards, computer mouse, etc. need a device driver to be installed first before they can be used. Again, these are device-specific.

Analog display drivers are used to display the output of analog devices. They use a circuit of adjustable voltage reference, a comparator and a stepped voltage divider.

Types of analog display drivers are:

§ Dot/bar display driver: Gives a display in dot mode and bar mode and is used to drive LEDs, LCD and VFD.

§ LCD drivers: They are used to drive LCD display units.

§ LED drivers: They are used to drive LCD display units.

§ Vacuum-fluorescent display drivers: They are used to display fluorescent displays.

§ Other types of display drivers are white LED display drivers, transformer-less EL display drivers, and SPI-compatible display drivers.

Factors for selection are:

§ Absolute accuracy: Difference of ideal and actual threshold voltage in dB.

§ Adjust pin current: Current from the reference pin with the voltage amplifier in the linear state.

§ Comparator gain: Change in output current divided by the change in input current.

§ Input bias current: Input current when the input buffer is linear.

§ Other factors are: offset voltage, input voltage/current rating, threshold voltage, etc.

Applications:

Analog display drivers are used to drive optocouplers, logic, relays, PNP transistors, extended range VU meters, vibration meters, 60 dB dot mode display, vacuum fluorescent display, liquid crystal display, LED display driver, bar display with alarm flasher, precision null meter, audio power meter, RF signal meter, etc.

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