PT6547 Datasheet, PDF (14/35 Pages) Princeton Technology Corp – LCD Driver IC with Key Input Function

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LCD Driver IC with Key Input Function
PT6547
VOLTAGE DETECTION TYPE RESET (VDET)
The Voltage Detection Type reset Circuit (VDET) generates an output signal and resets the systems
under the following conditions:
1. When power is initiated or first applied.
2. When the voltage drops (i.e. the Power Supply Voltages is less than or equal to the Power Down
Detection Voltage, VDET).
To insure that this function will operate properly, then a capacitor must be connected to the power
supply line so that the Power Supply Voltage VDD Rise Time when the power is first applied as well as
the Power Supply Voltage VDD fall time when the voltage drops are both at least 1ms.
RESET OF OUTPUT PINS STATE
The states of the output pins during the reset period are given in the table below.
Output Pin
SG1/P1 to SG8/P8
SG75/KS1, SG76/KS2
SG9 to SG73
COM4/SG74
COM1 to COM3
KS3 to KS5
KS6
DOUT
Note: x=Not Relevant
State during the
Reset Period
L
L
L
L
x
(see Note)
H
H
Remarks
These output pins are forcibly set to the
segment output function and held low.
-
This output pin is forcibly set to the common
output function and held low.
However, when the Command 1’s b0 control bit
is transferred, either the common output or the
segment output function is selected.
-
When the power is first applied, the states of
these output pins are undefined until the
command 4’s b2 and b1 control bits have been
transferred.
-
This output pin is an open-drain output, thus a
1k to 10kΩ pull-up resistor is needed. This pin is
kept at "HIGH" level during the reset period
even if the key data read operation is
performed.
PT6547 V1.2
- 14 -
January, 2006