ST7735
9.12 Power ON/OFF Sequence
VDD must be powered on before the VDDI.
VDDI must be powered off before the VDD.
During power off, if LCD is in the Sleep Out mode, VDD and VDDI must be powered down minimum 120msec after RESX
has been released.
During power off, if LCD is in the Sleep In mode, VDDI or VDD can be powered down minimum 0msec after RESX has
been released.
CSX can be applied at any timing or can be permanently grounded. RESX has priority over CSX.
Note 1: There will be no damage to the display module if the power sequences are not met.
Note 2: There will be no abnormal visible effects on the display panel during the Power On/Off Sequences.
Note 3: There will be no abnormal visible effects on the display between end of Power On Sequence and before receiving Sleep Out
command. Also between receiving Sleep In command and Power Off Sequence.
Note 4: If RESX line is not held stable by host during Power On Sequence as defined in the sequence below, then it will be necessary to
apply a Hardware Reset (RESX) after Host Power On Sequence is complete to ensure correct operation. Otherwise function is not
guaranteed.
The power on/off sequence is illustrated below
TrPW ≧ 0ns
TfPW ≧ 0ns
VDD
VDDI
Timing when the latter signal rises up to 90% of its typical value.
e.g. When VDD comes later, this timing is defined at the cross point of
90% of 2.75V, not 90% of 2.6V.
Timing when the latter signal falls up to 90% of its typical value.
e.g. When VDD comes later, this timing is defined at the cross point of
90% of 2.75V, not 90% of 2.6V.
TfPW-CSX = +/- no limit
TrPW-CSX = +/- no limit
CSX
H or L
TrPW-RESX = + no limit
RESX
(Power down in
sleep-out mode)
TfPW-RESX1 = min 120ms
30%
TrPW-RESX = + no limit
TfPW-RESX2 = min 0ms
RESX
(Power down in
sleep-in mode)
30%
TfPW-RESx1 is applied to RESX falling in the Sleep Out Mode.
TfPW-RESx2 is applied to RESX falling in the Sleep In Mode.
9.12.1 Uncontrolled Power Off
The uncontrolled power-off means a situation which removed a battery without the controlled power off sequence. It will
neither damage the module or the host interface.
If uncontrolled power-off happened, the display will go blank and there will not any visible effect on the display (blank
display) and remains blank until “Power On Sequence” powers it up.
V1.7
65
2009-12-04
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
