Datasheet

DS1878
SFP+ Controller with Digital LDD Interface
24 ______________________________________________________________________________________
DETECTION OF TXF FAULT
TXD OR TXF RESET
t
INITR1/2
TXFOUT
(ONLY ALARM FAULTS PRESENT)
TXFOUT
(QT ALARMS PRESENT)
Figure 17b. TXFOUT Latched Operation and TXD_TXFEN = 1
DETECTION OF TXF FAULT
TXFOUT
Figure 17a. TXFOUT Nonlatched Operation
By default, TXD does not impact TXFOUT (TXD_TXFEN =
0). This is shown in the Figure 17c. When TXD_TXFEN
= 1, TXD affects TXFOUT. The particular behavior is
described in Figure 17a and 17b.
VCCTXF is a new control bit is required to enable/dis-
able VCC LO alarm/warning before the first V
CC
con-
version is complete. If VCCTXF = 1, VCC LO
alarm/warning does not generate TXFOUT before the
first V
CC
conversion (which takes approximately 13ms
to complete). When VCCTXF = 0, VCC LO alarm/warn-
ing generates TXFOUT before the first V
CC
conversion,
which is illustrated in Figure 17c and Figure 17d.
Two conditions are shown. In the first instance, V
CC
powers on quickly and goes above the VCC LO thresh-
old before the first conversion is complete (approxi-
mately 13ms).
In the other instance, V
CC
would power up and go
above the VCC LO threshold after the first conversion is
complete. In this case TXFOUT behaves as in
Figure 17d.