SPC8104 S-MOS Systems, SPC8104 Datasheet - Page 306

• Manufacturer Part Number: SPC8104
• Description: VGA LCD CONTROLLER
• Manufacturer: S-MOS Systems

2.0
This power save mode has an Active State and a Power Down State. When Doze Mode 1 is
enabled the chip enters the Active state which is functionally the same as the normal operation. If
there is no memory or I/O write for at least two vertical frames, the output pixels are first re-
mapped to black and white. After two more frames with no memory or I/O write, XSCL is stopped.
The SPC8104F0A ensures that 1 complete frame, where the pixels are re-mapped to black and
white, has been transferred before stopping the XSCL signal.
Various internal blocks in the SPC8104 are also shut down to conserve power. The chip is now in
the Power Down State. Upon detecting a memory or I/O write, the disabled internal blocks are re-
enabled and XSCL is reactivated at the beginning of the next frame or the second to next frame.
2.1
RAM type LCD Drivers are drivers containing internal static RAM as well as having the ability to
generate the LC drive signals. This enables them to maintain display refresh of a static image.
The intended use of RAM type LCD Drivers are in applications where the display data is static for
long periods of time. This will allow the display controller and various other logic devices to be
shut down, thus saving power.
Self-Refresh Mode is the term referring to the situation where the transmission of display data is
suspended by the display controller and the displayed image is maintained by the LCD Driver’s
internal RAM. This Self-Refresh mode is automatically enabled when the data shift clock (XSCL)
is held a logic low for a number of horizontal display periods. The actual number of lines varies
between different RAM type LCD Drivers.
2.2
The power consumption of the SPC8104F0A when in Doze Mode 1 is 50% of normal mode oper-
ation. Refer to the SPC8104F0A VGA LCD Controller Power Consumption Application Note (X15-
AN-002-01) for complete details.
Power Save Mode-Doze Mode 1 Implementation Notes
U D [3:0]
AN1-6
Example shown: 320x240 Single 4-bit LCD
XSCL
YD
LP
DOZE MODE 1 OPERATIONAL DESCRIPTION
RAM type LCD Driver - Self-Refresh Mode
Power Consumption
S-MOS Systems, Inc. • Tel: [phone] • Fax: [phone] • http://www.smos.com
LINE 1
LINE 2
Pixels are re-mapped to black and white
LINE 3
LP : 240 PULSES
LINE 4
LINE 240
2 Frames of
inactivity
Doze Mode 1
Active
412-1.0
SPC8104