Toshiba e-STUDIO 206, Service Manual

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5
© February 2007 TOSHIBA TEC CORPORATION All rights reserved e-STUDIO166/206
CONTROL PANEL
5 - 5
5.4 Operation
5.4.1 Block diagram
The control panel is controlled by the serial data input/output to the SoC on the MAIN board.
The input status of each button is output to the SoC as serial data (OPKYSI) by the parallel-serial con-
version IC and detected. Each LED is controlled to be lit by the LED driver based on the information of
the serial data (OPLDSO) output from the SoC.
Fig. 5-2
5.4.2 LED display circuit
<Example> Lighting circuit method of “Cover open lamp”
Fig. 5-3
FET (Q2) is turned ON when the FET control signal (C0) becomes “L” level.
Then when the control signal (LEDM12) of the LED driver changes to “L” level, the current flows to the
cover open lamp (LED22) to turn ON the LED.
Conditions to turn ON the LED
The LED is turned ON only when the two conditions below are met.
1) The FET connected to the LED anode is ON.
2) The cathode side of the LED is “L” level.
Decoder
Hard-key matrix
+5V, +5VB
Buzzer ON signal
(BZON)
Serial data
(OPKYSI)
Serial data
(OPLDSO)
LED
driver
Buzzer
LED
Parallel-serial
conversion IC
MAIN board Control panel
SoC
ASIC
Low
Low
Cover open lamp
(LED22)
R
+5V
LEDM12
Current
C0 Q2