ST7577 Sitronix Technology, ST7577 Datasheet - Page 33

• Manufacturer Part Number: ST7577
• Description: Dot Matrix LCD Controller/Driver
• Manufacturer: Sitronix Technology

ST7577
Power OFF flow with built-in power circuits
USING PD BIT
By setting PD=”H”, ST7577 will go into power save mode. The LCD driving outputs are all fixed to V
circuits are turned OFF. After the built-in power circuits are turned OFF, the power (V
Note:
1.
2.
3.
4.
5.
6.
7.
8.
Ver 1.0a
t
t
It is NOT recommended to turn VDD OFF before VDD2. Without VDD, the internal status cannot be guaranteed and
internal discharge-process maybe stopped. The un-discharged power maybe polarizes the liquid crystal in panel.
IC will NOT be damaged if either VDD or VDD2 is OFF while another is ON.
The timing is dependent on panel loading and the external capacitor(s).
The timing in these figures is base on the condition that: LCD Panel Size = 1.5” with C1=1uF, C2=1uF.
Reset Low time after VDD2 is stable.
When turning VDD2 OFF, the falling time should follow the specification:
300ms ≤ t
IPOFF
V2OFF
: Internal Power discharge time. => 250ms (max).
: Period between VDD and VDD2 OFF time. => 50 ms (max).
PFall
Instruction Flow
≤ 1sec
33/48
DD
and V
DD2
) can be removed.
SS
and the built-in power
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2008/02/14