em6521 EM Microelectronic, em6521 Datasheet - Page 47

• Manufacturer Part Number: em6521
• Description: Mfp Version Of Em6621 Ultra Low Power Microcontroller With 4x20 Lcd Driver
• Manufacturer: EM Microelectronic

14 LCD Driver
The EM6521 has a built-in Liquid Crystal Display (LCD) driver. A maximum of 80 Segments can be displayed
using the 20 Segment driver outputs (SEG[20:1) in 4:1 multiplex ,60 Segments in the case of 3:1 multiplex, and
the 4 back-planes (COM[4:1]).
The LCD driver has its own voltage regulator (1.05 Volt) and voltage multiplier to generate the driver bias
voltages VL1, VL2 and VL3 (VLCD). Using the metal1 mask (ROM version only) the user can choose higher
LCD reference voltages. Please check with EM Marin the possible values and their impact on power
consumption.
The special architecture of this LCD driver allows the user to freely specify the data and address for each
individual Segment using the interconnect metal2 mask (ROM version only) . It therefore adapts to every
possible LCD display with a maximum of 80 independent segments. The LCD clock frequency is 256Hz. Thus
the frame frequency is 256/8 Hz if 4:1 multiplex, or 256/6 if 3:1 multiplex.
Copyright © 2005, EM Microelectronic-Marin SA
Figure 35. LCD Architecture
LCD External
LCD Blank
LCD Off
Supply
Address
Bus
R
Data
Bus
Data
Latches
1
2
3
4
Voltage
Multiplier
Enable
Phase 1 to 4
RefLCD
47
Phase
Selection
x3
x2
x1
Von
www.emmicroelectronic.com
MUX
EM6521
Voff
Output
Switches
SEG[n]
VL3
VL1
VL2