Display driver circuits are described for driving organic light emitting diode displays, particularly passive matrix displays with greater efficiency. Display driver control circuitry (506) comprises a frame memory interface (505) for reading data from a frame memory (504) for presentation on a passive matrix OLED display. A blank line identifier (507) identifies one or more substantially blank rows of pixels defined by the data in the frame memory and the control circuitry (506) skips past these rows when the passive matrix display is addressed. When blank lines are skipped the apparent brightness of the remaining lines increases and thus preferably the control circuitry includes a power controller (505) for reducing a power supply to the display in proportion to the number of skipped lines. The invention is particularly suited to a display driver providing a controlled current drive.