PCF2119AU NXP [NXP Semiconductors], PCF2119AU Datasheet - Page 8

• Manufacturer Part Number: PCF2119AU
• Description: LCD controllers/drivers Single-chip LCD controller and driver
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
8. Functional description
PCF2119X
Product data sheet
8.1.1 Timing generator
8.1.2 Internal clock
8.1.3 External clock
8.1 Oscillator and timing generator
8.2 Reset function and Power-On Reset (POR)
The internal logic and the LCD drive signals of the PCF2119x are timed by the frequency
f
f
The timing generator produces the various signals required to drive the internal circuitry.
Internal chip operation is not disturbed by operations on the data buses.
To use the on-chip oscillator, pin OSC must be connected to V
provides the clock signal for the display system. No external components are required.
If an external clock will be used, the input is at pin OSC. The resulting display frame
frequency is given by:
Remark: Only in the power-down mode the clock is allowed to be stopped (pin OSC
connected to V
liquid crystals.
The PCF2119x must be reset externally when power is turned on. If no external reset is
performed, the chip might start-up in an unwanted state.
For the external reset, pin POR has to be active HIGH. The reset has to be active for at
least 3 oscillator periods in order for the reset to be executed. If the internal oscillator is
used, the minimum reset activity time follows from the lowest possible oscillator frequency
(f
200 μs (typ) up to 300 μs (max) after power-on. In case that an external oscillator is used,
T
Afterwards the chip executes the Clear_display instruction, which requires 165 oscillator
cycles. After the reset the chip has the state shown in
clk
clk(ext)
osc
osc
f
which equals either the built in oscillator frequency f
fr
= 140 kHz, T
is dependent from f
.
=
----------- -
3072
f
osc
SS
All information provided in this document is subject to legal disclaimers.
), otherwise the LCD is frozen in a DC state, which is not suitable for the
osc
~ 71 μs, 3 × T
Rev. 7 — 15 November 2010
osc(ext)
.
osc
~ 215 μs). The internal oscillator start-up time is
Table 4
osc
or an external clock frequency
and is then ready for use.
DD1
LCD controllers/drivers
. The on-chip oscillator
PCF2119x
© NXP B.V. 2010. All rights reserved.
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