RA8835A
Version 1.0
6-2-2 SLEEP IN
Dot Matrix LCD Controller
Place the system in standby mode. This command has no parameter bytes. At least one blank
frame after receiving this command, the RA8835A halts all internal operations, including the
oscillator, and enters the sleep state.
Blank data is sent to the X-drivers, and the Y-drivers have their bias supplies turned off by the
YDIS signal. Using the YDIS signal to disable the Y-drivers guards against any spurious displays.
The internal registers of the RA8835A series maintain their values during the sleep state. The
display memory control pins maintain their logic levels to ensure that the display memory is not
corrupted. The RA8835A series can be removed from the sleep state by sending the SYSTEM
SET command with only the P1 parameter. The DISP ON command should be sent next to enable
the display.
Figure 6-9: SLEEP IN Instruction
1. The YDIS signal goes LOW between one and two frames after the SLEEP IN command is
received. Since YDIS forces all display driver outputs to go to the deselected output voltage,
YDIS can be used as a power-down signal for the LCD unit. This can be done by having YDIS
turn off the relatively high power LCD drive supplies at the same time as it blanks the display.
2. Since all internal clocks in the RA8835A series are halted while in the sleep state, a DC voltage
will be applied to the LCD panel if the LCD drive supplies remain on. If reliability is a prime
consideration, turn off the LCD drive supplies before issuing the SLEEP IN command.
3. Note that, although the bus lines become high impedance in the sleep state, pull-up or pull-
down resistors on the bus will force these lines to a known state.
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