ssd1325z Bolymin, Inc, ssd1325z Datasheet - Page 22

• Manufacturer Part Number: ssd1325z
• Description: 128 X 80, 16 Gray Scale Dot Matrix Oled/pled Segment/common Driver With Controller
• Manufacturer: Bolymin, Inc

There are three phases to driving an OLED a pixel. In phase 1, the pixel is reset by the segment driver to
V
electrode. The period of phase 1 can be programmed by command B1h A[3:0] from 1 to 15 DCLK. An
OLED panel with larger capacitance requires a longer period for discharging.
In phase 2, pre-charge is performed. The pixel is driven to attain the corresponding voltage level V
V
programmed in length from 1 to 15 DCLK by command B1h A[7:4]. If the capacitance value of the pixel
of OLED panel is larger, a longer period is required to charge up the capacitor to reach the desired voltage.
Last phase (phase 3 is current drive stage. The current source in the segment driver delivers constant
current to the pixel. The driver IC employs PWM (Pulse Width Modulation) method to control the gray
scale of each pixel individually. The wider pulse widths in the current drive stage results in brighter
pixels and vice versa. This is shown in the following figure.
After finishing phase 3, the driver IC will go back to phase 1 to display the next row image data. This
three-step cycle is run continuously to refresh image display on OLED panel.
The pulse width, which is counted from Phase 2 to Phase 3, is defined by command B8h “Set Gray Scale
Table”. In the table, the gray scale is defined in incremental way, with reference to the length of previous
table entry.
SS
SS
Solomon Systech
Segment
Voltage
. The amplitude of V
in order to discharge the previous data charge stored in the parasitic capacitance along the segment
V
V
SL
P
Phase1
Phase2
P
can be programmed by the command BCh. The period of phase 2 can be
Figure 12 : Gray Scale Control by PWM in Segment
Phase3
OLED
Panel
drives pixel brighter
Wider pulse width
Oct 2007
P 22/60
Rev 1.9
SSD1325
P
from