HOLTEK
HT1647
4-Level Gray Scale 64x16 LCD Controller for I/O uC
 Features

Operating voltage: 2.7V~5.2V

Time base or WDT overflow output
Built-in 32kHz RC oscillator Two selectable LCD frame frequencies: 89Hz or ---
External 32.768kHz crystal oscillator or 32kHz ---170Hz
---frequency source input Built-in buzzer driver (2kHz/4kHz)
Standby current: <1uA at 3V, <2uA at 5V Power down command reduces power consumption
Three data accessing modes Data mode and Command mode instructions
R/W address auto increment Internal resistor type: 1/5 bias or 1/4 bias, 1/16 duty
Max. 64x16 patterns, 64 segments and 16 commons Provides VLCD pin to adjust LCD operating voltage
Software configuration feature Provides three kinds of bias current programming
Built-in bit-map display RAM:2048 bits (=64x16x2 bits) Control of TN-type, STN-type LCDs and ECB--type
Built-in internal resistor type bias generator ---LCDs
Six-wire interface (four data wires) Four-level gray scale output for TN-type,STN-type
Eight kinds of time base/WDT selection --- LCDs panel
100-pin QFP and in chip form  
 General Description
HT1647 is a peripheral device specially designed for I/O type mC used to expand the display also e capability. The
max. display segment of the device are 1024 patterns (64 segments and 16 commons). It supports four data bits
interface, buzzer sound, Watchdog Timer or time base timer functions. The HT1647 is a memory mapping and
multi-function LCD controller. Since the HT1647 can control ECB-type (Electrically Controlled Birefringence) LCDs
in addition to current TN-type (Twisted Nematic) or STN type (Super Twisted Nematic) LCDs, it can support 4-color
display as well as 4-level gray scale display. It displays 4-level gray scale output when the HT1647 drives a TN-type,
STN-type LCDs. It displays four color output when the HT1647 drives an ECB-type. HT1647 uses PWM (Pulse
Width Modulation) technique. The software configuration feature of the HT1647 make it suitable for multiple LCD
applications including LCD modules and display subsystems. Only six lines (CSB, WRB, DB0~DB3) are required
for the interface between the host controller and the HT1647.