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News Release

April 21, 1998

Two Graphic Liquid Crystal Controller/Drivers, Providing Single-Chip Implementation of Graphic Display and Character Display for Mobile Communication Products

- Switchable between 96 x 42-dot Graphic Display and 5-Line x 16-digit Character Display in a single chip -

Hitachi, Ltd.(NYSE:HIT) today announced the release of two graphic liquid crystal controller/drivers for LCD displays in mobile communication products such as digital portable phones and PHS phones. The HD66726 supports both a 96 x 42-dot graphic display*1 and a 5-Line x 16-digit character display*2 in a single chip and the HD66725 supports both a 96 x 26-dot graphic display and a 3-Line x 16-digit character display, also in a single chip. Sample shipments of both products will begin in May 1998 in Japan.

These new products enhance Hitachi's lineup of graphic liquid crystal controller/driver series with the ability to provide a simple character display with the flexibility of a graphic display. The graphic liquid crystal controller/drivers will enable more sophisticated information services to be offered, while built-in key-scan functions will make it possible to create systems that are smaller, lighter, and lower- priced. These two products will be available in chip- with-bump*3 or TCP*4 mountings.

With the rapid growth of the market for mobile communication products such as portable and PHS phones, there are constant demands for lower power consumption, greater multifunctionality, reduced size and weight, and lower costs. With the increasing multifunctionality and higher added value of the small LCD displays used in these products, it has become necessary to provide not only a character display, based on kana and alphanumeric characters, but also a graphic display to implement such additional functions as kanji message communication, games, and schedulers. With existing graphic display systems, however, the character display is laborious and imposes a heavy software processing load on the microcomputer, leading to correspondingly long system development times.

In response to this problem, Hitachi has developed the new concept graphic liquid crystal controller/driver series capable of switching between graphic display and character display according to the display requirements of the system. The HD66724, switchable between a 72 x 26-dot graphic display and a 3-Line x 12-digit character display, was already in volume production as the industry's first graphic liquid crystal controller/driver.

The controller/drivers of new products have an on-chip low-power-consumption type liquid crystal drive power supply circuit, and include circuits for 4 x 8 key matrix control and control of three LEDs or back lights. Also included is a synchronous serial interface for interfacing to a microcomputer, and 68/80-type 8-bit and 4-bit interface functions.

Access to on-chip registers and RAM can be performed by continuous high-speed writing, independently of the internal operating clock frequency, enabling fast data transfer to be achieved. In addition, the built-in key-scan and port control functions make it possible to control the entire operating display, including the liquid crystal display and key matrix, via three serial interfaces. This makes it possible to use fewer parts and to cut the number of microcomputer I/O ports by more than 20, for example, resulting in lower system size, weight, power consumption, and costs.

Regarding display function, in graphic display the display data is written directly to the 96 x 42-dot (HD 66726) or 96 x 26-dot (HD66725) bit-mapped display RAM. Kanji message display, games, etc., can be supported by writing a kanji font or patterns to the display RAM. In character display, the display automatically generates character font pattern from 8-bit kanji. There are 432 fixed and 64 user-programmable 6 x 8-dot fonts, enabling a wide variety of characters to be displayed, including characters in boldface fonts and numerous national fonts. In addition, blink control can be performed for displaying marks such as pictograms and icons.

To achieve a further reduction in power consumption, the internal operating clock frequency has been lowered to 32 kHz from the previous 120 kHz, and event-driven operation, in which unnecessary operating clocks are stopped on an individual function block basis, is employed in the driver unit.

A newly supported feature is a partial display-on function that reduces power consumption to approximately 50% compared to previous Hitachi products, by minimizing the liquid crystal drive duty and drive bias, and the liquid crystal drive voltage, when displaying a "standby" or similar mark, or during time and similar displays which use only part of the display screen. Combined use of the internal oscillation clock stop function (standby function) and the liquid crystal drive power supply-off function provides power management that is finely tuned to synchronize the operation.

This power management system enables new products a drastic reduction in the total power consumption of the liquid crystal display system, including the liquid crystal drive power supply system. The power consumption figure is approximately 210 microwatt (HD66726) or 150 microwatt (HD 66725) during full-screen display and approximately 60 microwatt during pictogram display in standby mode, and approximately 3 microwatt with no display (stand by mode).

Supported mounting methods are COG*5 mounting, in which the device is directly mounted face-down on the LCD glass, COF*6 mounting, in which the device is mounted face-down on a flexible film substrate, and TCP mounting, in which the device is connected to the LCD glass via a heat seal. To minimize the mounting glass area in COG mounting, a slim chip shape is used, with a width of only 2.51 mm. In addition, the HD 66726 supports COB*7 mounting. Hitachi plans to expand the product lineup in the future, based on the present technology, to provide support for larger display sizes.

Notes:

  1. Graphic display: On-chip bit-mapped display RAM is provided, and the microcomputer can display arbitrary patterns such as kanji and game patterns by storing display data for individual dots.
  2. Character display: An on-chip character generator that generates font patterns is provided, and kana, alphanumeric, and similar character fonts in the character generator can easily be displayed simply by specifying one-byte character codes with a microcomputer.
  3. Chip-with-bump: A bare chip with a projecting gold electrode ("bump") on the aluminum pad section.
  4. TCP (Tape Carrier Package): A package in which the chip is mounted on a thin-film tape. Extremely thin type mounting (less than 1 mm) is possible.
  5. COG (Chip On Glass): A mounting method in which a chip with a gold bump is directly mounted face-down on the LCD glass. The thickness of the LCD module can be made as thin as the LCD glass.
  6. COF (Chip On Film): A mounting method in which a chip with a gold bump is directly mounted face-down on a flexible film substrate.
  7. COB: Chip On Board

Application Product Examples

  • Digital cellular phones (PDC, GSM, CDMA, etc.), PHS, Pagers
  • Digital cordless phones, Multifunctional business phones,
  • Portable MD players, simple portable terminals (electronic wallets, POS, etc.)

Pricing in Japan
Product
Name
Graphic
Display Size
Shipment
Form
Mounting
Form
SamplePrice
(Yen)
HCD66725BP 96 x 26 dots Chip with
gold bump
COG, COF 300
HD66725TA0 96 x 42 dots Straight TCP TCP 500
HCD66726BP 96 x 42 dots Chip with
gold bump
COG, COF 400
HCD66726 96 x 42 dots die COB 380
HD66726TB0 96 x 42 dots TCP
(bend type)
TCP 600

Specifications
ItemSpecifications
Product Name HD66725 HD66726
Graphic display size 96 x 42 dots 96 x 26 dots
Number of character display characters 3 lines x 16 digits (6 x 8-dot font) 5 lines x16 digits (6 x 8-dot font)
Number of mark displays 192 192
Key-scan functions
  • 4 x 8 (32-key) matrix control
  • Key-scan interrupt generation
Number of fonts (6 x 8 dots)
  • Built-in fixed fonts: 432
  • User-programmable fonts: 64
Display functions
  • Graphic/ Character display switching
  • Horizontal smooth scroll display
  • Vertical smooth scroll display
  • Vertical double-size display
  • (perpendicular enlarged display function)
  • Cursor display per display line
  • Blink mark display support
Liquid crystal drive duty 1/2, 1/10, 1/18, 1/26 duty
(programmable)
1/2, 1/10, 1/18,1/26,1/34, 1/42 duty
(programmable)
Liquid crystal
drive bias
1/4 to 1/6.5 bias
(programmable)
1/2 to 1/8 bias
(programmable)
Power consumption
control functions
  • Sleep mode, standby mode
  • Variable liquid crystal drive duty/bias/voltage
  • Liquid crystal drive power supply on/off function
System interfaces
  • Synchronous serial interface
  • 68/80-type 4-bit bus interface
  • 68/80-type 8-bit bus interface
Liquid crystal
step-up circuit
On-chip step-up
circuit with x1/x2/x3
On-chip step-up
circuit with x1/x2/x3/x4
Liquid crystal drive
power supply circuit
  • On-chip liquid crystal drive level power supply operational amplifier
  • On-chip liquid crystal drive level bleeder resistance
  • On-chip electronic control for contrast adjustment
Number of general
output ports
3 3
Operating power
supply voltage
1.8 V to 5.5 V (liquid crystal drive voltage: 3 V to 6 V) 1.8 V to 5.5 V (liquid crystal drive voltage: 3 V to 11 V)
Power consumption
(Internal logic
block + liquid
crystal drive
power supply block)
VCC = 3 V
  • Full-display mode: 150 microwatt typ.
  • Mark display only: 60 microwatt typ.
  • No display (stand by mode): 3 microwatt typ.
  • Full-display mode: 210
  • microwatt typ.
  • Mark display 60 microwatt typ.
  • No display (stand by mode): 3 microwatt typ.
Mounting forms
  • Chip with gold bump (for COG or COF
    mounting)
  • Straight TCP
  • Chip with gold
    bump (for COG or COF mounting) only: 60
  • die(for COB
    mounting)
  • TCP(bend type)


WRITTEN BY Secretary's Office
All Rights Reserved, Copyright (C) 1998, Hitachi, Ltd.