MC141539 View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC141539

LCD Segment / Common Driver with Controller

Motorola => Freescale 

Display Timing Generator

This module is an on chip low power RC oscillator circuitry (Figure

6). The oscillator frequency can be selected in the range of 15 kHz to

50 kHz by external resistor. One can enable the circuitry by software

command. For external clock provided, feed the clock to OSC2 and

leave OSC1 open.

Annunciator Control Circuit

The LCD waveform of the 4 annunciators and BP are generated

by this module. The 4 independent annunciators are enabled by soft-

ware command. Annunciator is also controlled by oscillator circuit

too. the annunciators pins output 0V when oscillator is disabled.

Annunciator output waveform shown in Figure 7.

Internal Oscillator Selected

enable1 enable2

Oscillation Circuit

OSC1

OSC2

Oscillator enable

enable

Buffer

MC141539

External component

Feedback for internal oscillator

For external CLK input

Figure 6. Oscillator Circuitry

BP

ANNUN1

ANNUN2

DVDD

DVSS

DVDD

DVSS

DVDD

DVSS

ANNUN1

ANNUN2

OFF

ON

ON

ON

OFF

OFF

ON

ON

ON

OFF

OFF

OFF

Figure 7. Annunciators and BP Display Waveform

LCD Driving Voltage Generator

This module generates the LCD voltage needed for display output.

It takes a single supply input and generate necessary bias voltages.

It consists of :

1. Voltage Doubler and Voltage Tripler

To generate the Vcc voltage. Either Doubler or Tripler can be

enabled.

2. Voltage Regulator

Feedback gain control for initial LCD voltage. It can also be used

with external contrast control.

3. Voltage Divider

Divide the LCD display voltage (VLL2-VLL6) from the regulator out-

put. This is a low power consumption circuit which can save the

most display current compare with traditional resistor ladder

method.

4. Self adjust temperature compensation circuitry

Provide 4 different compensation grade selections to satisfy the

various liquid crystal temperature grades. The grading can be

selected by software control.

5. Contrast Control Block

Software control of 16 voltage levels of LCD voltage.

6. Bias Ratio Selection circuitry

Software control of 1/5 and 1/7 bias ratio to match the characteris-

tic of LCD panel.

All blocks can be individually turned off if external voltage genera-

tor is employed

32 Bit Latch / 120 Bit Latch

A 152 bit long register which carries the display signal information.

First 32 bits are Common driving signals and other 120 bits are Seg-

ment driving signals. Data will be input to the HV-buffer Cell for

bumping up to the required level.

Level Selector

Level Selector is a control of the display synchronization. Display

voltage can be separated into two sets and used with different

cycles. Synchronization is important since it selects the required LCD

voltage level to the HV Buffer Cell for output signal voltage pump.

HV Buffer Cell (Level Shift-er)

HV Buffer Cell works as a level shift-er which translates the low

voltage output signal to the required driving voltage. The output is

shifted out with an internal FRM clock which comes from the Display

Timing Generator. The voltage levels are given by the level selector

which is synchronized with the internal M signal.

Reference Generator

Two reference generators on chip to provide reference voltage to the

regulator circuitry. The VR (LCD driving voltage) stability is affected

by the performance of the reference voltage. For details on it's perfor-

mance, please refer to electrical characteristic.

MOTOROLA

MC141539

3–133

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