General Description
The HT1621 is a 128 pattern (32x4), memory mapping, and multi-function LCD driver. The S/W configuration feature of the HT1621 makes it suitable for multiple LCD applications including LCD modules and display subsystems. Only three or four lines are required for the interface between the host controller and the HT1621. The HT1621 contains a power down command to reduce power consumption.

FEATUREs
● Operating voltage: 2.4V~5.2V
● Built-in 256kHz RC oscillator
● External 32.768kHz crystal or 256kHz frequency
   source input
● Selection of 1/2 or 1/3 bias, and selection of 1/2 or
   1/3 or 1/4 duty LCD applications
● Internal time base frequency sources
● Two selectable buzzer frequencies (2kHz/4kHz)
● Power down command reduces power consumption
● Built-in time base generator and WDT
● Time base or WDT overflow output
● 8 kinds of time base/WDT clock sources
● 32x4 LCD driver
● Built-in 32x4 bit display RAM
● 3-wire serial interface
● Internal LCD driving frequency source
● Software configuration feature
● Data mode and command mode instructions
● R/W address auto increment
● Three data accessing modes
● VLCD pin for adjusting LCD operating voltage
● HT1621: 48-pin SSOP package
   HT1621B: 48-pin DIP/SSOP/LQFP package
   HT1621D: 28-pin SKDIP package
   HT1621G: Gold bumped chip