Datasheet

DS1886
SFP and PON ONU Controller
with Digital LDD Interface
26Maxim Integrated
Digital I/O Pins
Five digital inputs and three digital output pins are pro-
vided for monitoring and control.
LOS, LOSOUT
By default, the LOS pin is used to convert a standard
comparator output for loss of signal (LOS) to an open-
collector output (LOSOUT). The status of LOS can be read
in the STATUS byte (A2h Lower Memory, Register 6Eh) as
the RXL bit. The RXL signal can be inverted (INV LOS = 1)
before driving the open drain output transistor.
RSEL
The level of RSEL can be read by reading the STATUS
register (A2h Lower Memory, Register 6Eh). The status
of RSEL determines whether SETLOSL or SETLOSH is
written to the MAX3945 register SET_LOS.
TXD, TXDOUT
TXDOUT is generated from a combination of TXFOUT
and TXD (see the CNFGC register A2h Table 02h,
Register 8Bh for enabling these options). A software
control identical to TXD is available (TXDC, A2h Lower
Memory, Register 6Eh). A TXD pulse is internally extend-
ed (t
INITR1
) to inhibit the latching of low alarms and
warnings. The intended use is a direct connection to the
MAX3710’s DISABLE input if this is desired. When V
CC
<
POA, TXDOUT is high impedance.
IN1, TXF, Transmit Fault (TXFOUT) Output
TXFOUT can be triggered by all alarms and warnings and
also the pins TXF and IN1 (Figure 10). The ADC alarms and
warnings require enabling (A2h Table 01h/05h, Registers
Figure 10. TXFOUT and TXDOUT Logic Diagram.
Figure 11. RSEL Logic Diagram
C
C
D
Q
Q
R
OUT IN
TXDS
R
PU
TXFS
TXFOUTS
TXD
TXFINT
t
INITR1
TXDC
V
CC
TXD
TXDOUT
TXDIO
TXDFLT
FAULT RESET TIMER
(130ms)
IN
OUT
POWER-ON
RESET
PINS
INVTXF
TXF
TXFOUT
IN1S
IN1EN
IN1
RSEL
RSELS
3-WIRE
SET_LOS_3945
= PINS