點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Note that a complete set of 36 clocks must be sent in order to clear the shift registers. When
ST2225A is powered ON, reset signal is generated internally to reset all registers and all latches.
Then, the START bit and the first clock make it return to its normal operation.
Figure 2 shows the pin-out of the package for ST2225A. Figure 3 shows the pad-assignment of
the bare chip for ST2225A.The timing relationships between data, clock and DATA ENABLE is
shown in Figure 4, with maximum clock frequency of 0.5 MHz assumed.
When this driver is used for applications with lesser number of outputs, the current per output
can be increased, or the part can be operated at higher than 1V (Vout). The following equation can be
used for calculations.
Tj = (Vout) (ILED) (NO. of segments) (82℃/W)+TA
Where:
Tj = junction temperature (150℃ max)
Vout = the voltage at the LED driver outputs
ILED = the LED current
82℃/W = thermal resistance of the package
TA = ambient temperature
The above equation was used to plot Figure 6-8.
CLOCK
DATA
300 nS MIN
DATA ENABLE
100 nS MIN
Figure 4
LED Display Driver
-7-
Version：A.025
SITI [ SILICON TOUCH TECHNOLOGY INC. ]
