Rainbow Electronics DS1862 - Manual (Page 22)

DS1862
XFP Laser Control and Digital Diagnostic IC
22 ____________________________________________________________________
Warning and Alarm Logic Based on
Signal Conditioners
The DS1862 also has flags that are set by certain logical
conditions on signal conditioner (SC) pins: SC-RX-LOL,
SC-RX-LOS, SC-TX-LOS. Similarly, for each latched
signal conditioner flag there are also mask bits that are
capable of preventing the alarm or warning flag from
causing an
INTERRUPT pin to assert. Again, flags are
cleared automatically whenever their memory address
is read. See Figure 11 for more detail.
Quick-Trip Logic and FTEG
Shutdown Functionality
In addition to alarms and warnings, the DS1862 also
has quick-trip (QT) functionality (sometimes referred to
as fast alarms) that is capable of shutting down the
LASER with the FETG pin in conjunction with shutting
down I
MODSET and I BIASSET . I BMD and I BIASSET cur-
rents are measured and are compared with user-
defined trip points to set the quick-trip flags: QT LOW
TX-P, QT HIGH TX-P, and QT HIGH BIAS. These flags
are also capable of being masked to prevent FETG
from being asserted when an out-of-tolerance condition
is detected. FETG is not asserted by setting the TX-D
pin, SOFT TX-D, or P-DOWN/RST pin to a high state,
however, I
MODSET
, and I
BIASSET
will shut down. See
Figure 12 for more detail.
SIGNAL CONDITIONER AND MISCELLANEOUS LOGIC
ANY FLAG
ANY MASK BIT
HIGH TX-P
LOW TX-P LATCHED-TX-FAULT
HIGH BIAS
INTERRUPT (PIN)
TIMER
LA
TCH
SC-RX-LOS
(PIN)
LATCHED-RX-NR
SC-RX-LOL
(PIN)
LA
TCH
SC-TX-LOS
(PIN)
LATCHED-TX-NR
LATCHED-TX-FAULT
LA
TCH
P-DOWN/RST
(PIN)
LATCHED-RESET-DONE
LATCHED
RX-CDR-NL
LA
TCH
LA
TCH SC-RX-LOL
(PIN)
LATCHED-
RX-LOS
RX-LOS (PIN)
*OPEN DRAIN
LA
TCH SC-RX-LOS
(PIN)
SC-RX-LOL (PIN)
TX-FAULT
LATCHED-
MOD-NR
VCC2-FAULT
*OPEN DRAIN
MOD-NR (PIN)
LA
TCH
Figure 11. Signal Conditioner and Other Logic