Toshiba e-studio281c - LED Display Circuit

e-STUDIO281c/351c/451c © 2005 - 2008 TOSHIBA TEC CORPORATION All rights reserved
CONTROL PANEL
5 - 14
5.4.2 LED display circuit
1) Method of LED display
ex) Displaying “COPY”.
Fig. 5-9
Transistor is turned ON when the LDON 0 signal becomes “L” level.
Also, when LED driver pin changes to “L”, the current flows from 5VL via the transistor to the LED
(“COPY”) to turn ON the LED (“COPY”).
(a) The transistor (Q3) connected to the LED anode is ON.
(b) The output from the cathode side of the LED is “L” level.
The LED turns ON when the conditions (a) and (b) are met.
Conditions to turn ON the LED
LDON0
"L"
"L"
Q3
LED
driver
(COPY)
5VL
LED
G
Current