AK2546 Datasheet, PDF (22/27 Pages) Asahi Kasei Microsystems – 7 channel T1 Transceiver

ASAHI KASEI
[AK2546]
THEORY OF OPERATION
Loss of signal
Loss of signal in channel x is reported by setting LOSx register “high”.
The receiver will indicate loss of signal upon receiving 175 consecutive zeros or detecting input
level being below the threshold (ALOS).
LOSx returns to “low” when the received signal returns to 12.5% ones density and not including
100 consecutive zeros. (GR-820)
When Loss of Signal is detected in channel x, LOSx register is set “high” and LOSx pin becomes
“high”. When LOSx is set “high”, interrupt will be issued on INT pin if MLOSx is “low”. LOSx
pin becomes high regardless of MLOSx status. MLOSx is active-high and masks LOSx interrupt.
LOSx registers and LOSx pins represent the current status of received signal regardless of the
MLOSx status.
Loss of TCLK
Loss of TCLKx is reported by setting LOTCx “high”. When LOTCx is set “high”, INT output
becomes “high” if MLOTCx is “low”. MLOTCx is active-high and masks LOTCx interrupt.
LOTCx represents the current status of TCLKx and can be read regardless of MLOTCx status.
When Loss of TCLKx is detected, TTIPx/TRINGx will be forced to “0”.
Loss of MCLK
Loss of MCLK is reported by setting LOMC “high”. When LOMC is set “high”, INT output
becomes “high” if MLOMC is “low”. MLOMC is active-high and masks LOMC interrupt.
LOMC represents the current status of MCLK and can be read regardless of MLOMC status.
When the loss of MCLK is detected, LOSx register and LOSx pin goes “high” at the same time.
Therefore all MLOSx register must be set to “high” to prevent loss of MCLK from setting INT
output
INT output
INT output becomes “high” when the alarm is reported to any one of LOSx, LOTCx or LOMC
registers. This pin can be masked by MLOSx, MLOTCx or MLOMC registers.
Local Loopback
In Local Loopback mode, TPOSx, TNEGx, TCLKx signals are looped back to RPOSx, RNEGx,
RCLKx output. RTIPx, RRINGx inputs are ignored but loss of signal detection is active.
The transmitter in channel x outputs TTIPx, TRINGx normally.
Remote Loopback
In Remote Loopback mode, RTIPx/RRINGx signals are looped back to TTIPx/TRINGx output.
The receiver in channel x output RPOSx, RNEGx, RCLKx normally and detect loss of signal.
TPOSx, TNEGx, TCLKx inputs are ignored.
C0019-E-01
22
1999/9