Rainbow Electronics DS1874 - Manual (Page 25)

Initialization
During initialization, the DS1874 transfers all its 3-wire
EEPROM control registers to the MAX3798/MAX3799.
The 3-wire control registers include the following:
• RXCTRL1
• RXCTRL2
• SET_CML
• SET_LOS
• TXCTRL
• IMODMAX
• IBIASMAX
• SET_PWCTRL
• SET_TXDE
The control registers are first written when V CC exceeds
POA. They are also written if the MAX3798/MAX3799
TX_POR bit is set high (visible in 3W TXSTAT1, bit 7). In
the MAX3798/MAX3799, this bit is “sticky” (latches high
and is cleared on a read). They are also updated on a
rising edge of TXD. Any time one of these events
occurs, the DS1874 reads and updates TXSTAT1 and
TXSTAT2 and sets SET_IBIAS and SET_IMOD in the
MAX3798/MAX3799 to 0.
DS1874
SFP+ Controller with Digital LDD Interface
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MAX3798/MAX3799 Register Map and DS1874 Corresponding Location
MAX3798/MAX3799 REGISTER FUNCTION REGISTER NAME DS1874 LOCATION
Receiver Control 1 RXCTRL1 Table 02h, E8h
Receiver Control 2 RXCTRL2 Table 02h, E9h
Receiver Status RXSTAT Lower Memory, 6Eh, Bit1
Output CML Level Setting SET_CML Table 02h, EAh
LOS Threshold Level Setting SET_LOS Table 02h, EBh
Transmitter Control TXCTRL Table 02h, ECh
Transmitter Status 1 TXSTAT1 Table 02h, FCh
Transmitter Status 2 TXSTAT2 Table 02h, FDh
Bias Current Setting SET_IBIAS/BIAS Table 02h, CBh–CCh
Modulation Current Setting SET_IMOD/MODULATION Table 02h, 8Ah–8Bh
Maximum Modulation Current Setting IMODMAX Table 02h, EDh
Maximum Bias Current Setting IBIASMAX Table 02h, EEh
Modulation Current Increment Setting MODINC (see Note)
Bias Current Increment Setting BIASINC
Automatically performed by APC loop. Disable
APC before using 3-wire manual mode. Manual
Mode: Table 02h, F8h–FAh
Mode Control MODECTRL (see Note)
Transmitter Pulse-Width Control SET_PWCTRL Table 02h, EFh
Transmitter Deemphasis Control SET_TXDE Table 02h, F0h
Note: This register is not present in the DS1874. To access this register, use manual operation (see the Manual Operation section).