Rainbow Electronics DS1874 - Manual (Page 84)

DS1874
SFP+ Controller with Digital LDD Interface
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Table 02h, Register FDh: TXSTAT2
FACTORY DEFAULT 00h
READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246)
WRITE ACCESS N/A
MEMORY TYPE Volatile
FDh 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0
BIT 7 BIT 0
MAX3798/MAX3799 register. This value is read from the MAX3798/MAX3799 with the 3-wire interface every t RR
(see the MAX3798/MAX3799 electrical characteristics).
FACTORY DEFAULT 00h
READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246)
WRITE ACCESS PW2 or (PW1 and RWTBL246)
MEMORY TYPE Volatile
These registers are reserved.
FACTORY DEFAULT 00h
READ ACCESS PW2 or (PW1 and RWTBL246) or (PW1 and RTBL246)
WRITE ACCESS PW2 or (PW1 and RWTBL246)
MEMORY TYPE Nonvolatile (EE)
80h–C7h 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0
BIT 7 BIT 0
The digital value for the modulation DAC output.
The MODULATION LUT is a set of registers assigned to hold the temperature profile for the MODULATION
REGISTER. The values in this table determine the set point for the modulation voltage. The temperature
measurement is used to index the LUT (TINDEX, Table 02h, Register 81h) in 2°C increments from -40°C to
+102°C, starting at 80h in Table 04h. Register 80h defines the -40°C to -38°C MOD output, Register 81h defines
the -38°C to -36°C MOD output, and so on. Values recalled from this EEPROM memory table are written into the
MODULATION REGISTER (Table 02h, Register 82h–83h) location that holds the value until the next temperature
conversion. The DS1874 can be placed into a manual mode (MOD EN bit, Table 02h, Register 80h), where the
MODULATION REGISTER is directly controlled for calibration. If the temperature compensation functionality is
not required, then program the entire Table 04h to the desired modulation setting.
Table 02h, Register FEh–FFh: RESERVED
Table 04h Register Description
Table 04h, Register 80h–C7h: MODULATION LUT