Toshiba e-STUDIO170F Service Manual page 290

EU/AU models
NCU PBA
Lb
4
Line
The line current detect circuit consists of the line current detection IC (IC2), ASIC (I/O port: IC38) on the
Main PBA, and other peripheral devices. It detects a dial tone and the hook status of the external tele-
phone from the current flowing through the line.
When a dial tone is input from the telephone line, current flows through the line. The line current detec-
tion IC sends the REVA and REVB to the ASIC as pulse signals. This allows a dial tone to be detected.
Signal Name
REVA
REVB
e-STUDIO170F Circuit Description
1
IC2
Line current
detection IC
R25
2
Type Active
I - Line current detect signal
I - Current reverse line current detect signal
8 19
7 20
Fig.7-42
Description
7 - 60
Main PBA
REVA
19 36
IC38
ASIC
( I/O port )
REVB
20 37
Destination
ASIC
ASIC
January 2005 © TOSHIBA TEC