ST2226A SiTi, ST2226A Datasheet - Page 19

• Manufacturer Part Number: ST2226A
• Description: PWM-Controlled Constant Current Driver
• Manufacturer: SiTi

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frame rate or the no. shift-in pixels or grayscale level for each pixel.
Surely out of spec. Can’t realize in this configuration. System designs for ON-OFF type drivers thus need to reduce
that the PWM takes 1024 GCLK cycles and is one-shot. So we can issue up to
163K/1024=160 PWM cycles within a frame. This can be used as an 160-level total
brightness control in addition to the 1024-level pixel-dependent luminance control.
These 160- “LED1 Emitting” shall be issued periodically within a frame. Each time
when issuing the “LED1 Emitting” command, the shift-in process will be pended for a
few cycles; however, we can resume feeding the data right after the “LED1 Emitting”
command is issued.
should be issued. To make the total brightness half of the full scale, we can issue
80-“LED1 Emitting” commands in companion with 80-“LED Disable” commands, so
that all the 128*128 LEDs are half of their brightness.
reference.
ST2226A
Within a frame, there are 1024*16*10=163K DCLK & GCLK cycles, and we know
To make the total brightness at full scale, all 160 “LED1 Emitting” commands
A comparison table for PWM LED driver vs. ON-OFF type is provided for
點晶科技股份有限公司
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
點晶科技股份有限公司
點晶科技股份有限公司
Table 2. Comparison between PWM and ON-OFF Free Running
Frame rate
No. shift-in pixels
Grayscale for each pixel
Grayscale for overall
panel
Clocks needed per frame 167k
Clock rate
Version ： ： ： ： A.010
PWM
60
128 x 128 128 x 128
1024
160
10 MHz
ON-OFF
60
1024
1
16.8Meg
1.0 GHz
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ST2226A