Rainbow Electronics DS1876 - Manual (Page 17)

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DS1876
SFP Controller with Dual LDD Interface
Figure 7. 3-Bit (8-Position) Delta-Sigma Example
Figure 8. DAC OFFSET LUTs
When temperature controlled, the DACs are updated
after each temperature conversion.
The reference input, REFIN, is the supply voltage for the
output buffer of all four DACs. The voltage connected to REFIN and its decoupling must be able to support the
edge rate requirements of the delta-sigma outputs. In
a typical application, a 0.1FF capacitor should be con-
nected between REFIN and ground.
O
1
2
3
4
5
6
7
DAC OFFSET LUTs (04h/06h)[A2h/B2h]
EIGHT REGISTERS PER DAC
0
255
511
DELTA-SIGMA DACs
767
1023
EACH OFFSET REGISTER CAN BE INDEPENDENTLY SET BETWEEN
0 AND 1020. 1020 = 4 x FFh. THIS EXAMPLE ILLUSTRATES POSITIVE
AND NEGATVE TEMPCO.
DAC
LUT
BITS
7:0
F8h
DAC
LUT
BITS
7:0
F9h
DAC
LUT
BITS
7:0
FAh DAC
LUT
BITS
7:0
FBh
DAC
LUT
BITS
7:0
FCh
DAC
LUT
BITS
7:0
FDh
DAC
LUT
BITS
7:0
FEh
DAC
LUT
BITS
7:0
FFh
0
255
511
-40°C -8°C +8°C +24°C +40°C +56°C +70°C +88°C +104°C
DELTA-SIGMA DACs
767
1023
EACH OFFSET REGISTER CAN BE INDEPENDENTLY
SET BETWEEN 0 AND 1020. 1020 = 4 x FFh. THIS
EXAMPLE ILLUSTRATES POSITIVE TEMPCO.
DAC
LUT
BITS
7:0
F8h
DAC
LUT
BITS
7:0
F9h
DAC
LUT
BITS
7:0
FAh DAC
LUT
BITS
7:0
FBh
DAC
LUT
BITS
7:0
FCh
DAC
LUT
BITS
7:0
FDh
DAC
LUT
BITS
7:0
FEh
DAC
LUT
BITS
7:0
FFh
DAC OFFSET LUTs (04h/06h)[A2h/B2h]
EIGHT REGISTERS PER DAC
-40°C -8°C +8°C +24°C +40°C +56°C +70°C +88°C +104°C