AN3981 datasheet(49/54 Pages) STMICROELECTRONICS

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AN3981

Common application information

Doc ID 022217 Rev 1

49/54

Figure 59.

LED matrix panel driving solution

Eight channels out of sixteen are connected to the common cathodes (8 cathodes per

channel) and, if turned on, sink current from 1 to 8 LEDs (according to the number of LEDs

activated in each column).

The remaining channels are dedicated to driving the base of 8 transistors (used as

switches), each one used to connect or not eight anodes (of the same row) to the LED

voltage rail (if any, or to VCC if the voltage supply is the same as that which sources the IC).

The timing diagram in Figure 60 shows how to send data properly in order to correctly

display the desired information.

Each 16-bit group is used to select the row (bit 15 to bit 8) and the column (bit 7 to bit 0) of

the matrix. The complete image, considering a matrix of 8x8, is built in 8 cycles. Each cycle

is used to select a row (activating more columns) or a column (activating more rows).

AN3981 bảng dữ liệu(PDF) 49 Page - STMicroelectronics