User guide

DS1875
Table 02h, Register FBh to FCh: BIAS DAC
FACTORY DEFAULT 8000h
READ ACCESS PW2
WRITE ACCESS N/A
MEMORY TYPE Volatile
FBh BOL 0 2
12
2
11
2
10
2
9
2
8
2
7
FCh 2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
BIT 7 BIT 0
The bias open-loop bit (BOL) reflects the status of the BIAS current-control loop. If it is 1, the loop is open and
the DS1875 is controlling the BIAS output from the LUT. If it is 0, the loop is closed and the BIAS output is
controlled by active feedback from the BMD pin. The remaining bits are the digital value used for the BIAS
output regardless of the value of OL.
Table 02h, Register FDh: BIAS OL
FACTORY DEFAULT 00h
READ ACCESS PW2
WRITE ACCESS PW2 and APC EN = 1
MEMORY TYPE Volatile
FDh 2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
BIT 7 BIT 0
The digital value used for BIAS at power-on and during open loop. It is recalled from Table 08h at the adjusted
memory address found in TINDEX. This register is updated at the end of the temperature conversion. The
correct value depends on the value of BOLFS (Table 02h, Register 89h, bit 3).
If BOLFS = 0, BIAS OL[7:0] = I
BIAS
[11:4].
If BOLFS = 1, BIAS OL[7:0] = I
BIAS
[12:5].
PON Triplexer and SFP Controller
______________________________________________________________________________________ 85