Reset Circuit - Toshiba e-STUDIO170F Service Manual

7.3.5

Reset Circuit

Main PBA
Flash ROM ( IC23: Pin12 )
USB controller ( IC49: Pin46 ( via AND ))
ASIC ( I/O port: IC38: Pin70 )
DSC ( IC27: Pin32 )
ASIC ( I/O port for operation panel: IC4: Pin70 )
36
IC15
ASIC
( Engine controller )
37
3.3V
5
IC42
C206
4
Reset IC
When the logic voltage is unstable as the power switch is turned on, and so on, or an abnormal condi-
tion has occurred in the system, the reset circuit resets the respective IC's to prevent them from mal-
functioning.
When the voltage of 3.3V delivered from the LVPS is 2.9V or under, the PWRESETX signal output from
the Reset IC (IC42) will go LOW. This causes the RESETX signal output from the AND (IC18) to go
LOW to reset the entire system including the ASIC (Engine controller: IC15), and USB controller (IC49).
Also, when the PWRESETX signal goes LOW, Q108 will be turned on and reset the Main-CPU (IC22).
In case an abnormal condition has occurred in the system and the Main-CPU crashes, the ASIC
causes the ROUTX signal to go LOW to turn on Q108. This causes the RESETX signal to go LOW to
reset the entire system.
Signal Name
PWRESETX
RESETX
ROUTX
e-STUDIO170F Circuit Description
5VRESX
ROUTX
3.3V
R213
PWRESETX
1
2
Type Active
O L Power ON reset signal
I L Reset signal
O L Watchdog reset signal
13 7
IC31
Bus transceiver
( 3.3V +5V )
IC18
RESETX
4
IC19
2
1
Fig.7-23
Description
7 - 30
3.3V
R274
IC22
2 10
1
Main-CPU
4
Q108
Destination
IC19
Each IC
IC5
January 2005 © TOSHIBA TEC