Rainbow Electronics MAX3799 - Manual (Page 26)

MAX3799
Modulation Current Increment Setting Register (MODINC)
Bit 7: SET_IMOD[0]. This is the LSB of the SET_IMOD[8:0] bits. This bit can only be updated by the use of
MODINC[4:0].
Bit 5: DE_INC. When this bit is set to 1 and the deemphasis on the transmit output is enabled, the SET_TXDE[3:0] is
incremented or decremented by 1 LSB. The increment or decrement is determined by the sign bit of the MODINC[4:0]
string of bits.
Bits 4 to 0: MODINC[4:0]. This string of bits is used to increment or decrement the modulation current. When written
to, the SET_IMOD[8:0] bits are updated. MODINC[4:0] are a two’s complement string.
Bias Current Increment Setting Register (BIASINC)
Bit 7: SET_IBIAS[0]. This is the LSB of the SET_IBIAS[8:0] bits. This bit can only be updated by the use of BIASINC[4:0].
Bits 4 to 0: BIASINC[4:0]. This string of bits is used to increment or decrement the bias current. When written to, the
SET_IBIAS[8:0] bits are updated. BIASINC[4:0] are a two’s complement string.
Mode Control Register (MODECTRL)
Bits 7 to 0: MODECTRL[7:0]. The MODECTRL register enables a switch between normal and setup modes. The
setup mode is achieved by setting this register to H0x12. MODECTRL must be updated before each write operation.
Exceptions are MODINC and BIASINC, which can be updated in normal mode.
Transmitter Pulse-Width Control Register (SET_PWCTRL)
Bits 3 to 0: SET_PWCTRL[3:0]. This is a 4-bit register used to control the eye crossing by adjusting the pulse width.
1Gbps to 14Gbps, SFP+ Multirate Limiting
Amplifier and VCSEL Driver
26 ______________________________________________________________________________________
Bit # 7 6 5 4 3 2 1 0 ADDRESS
Name
SET_IMOD
[0]
X DE_INC
MODINC[4]
(MSB)
MODINC[3] MODINC[2] MODINC[1]
MODINC[0]
(LSB)
Default Value 0 0 0 0 0 0 0 0
H0x0C
Bit # 7 6 5 4 3 2 1 0 ADDRESS
Name
SET_IBIAS
[0]
X X
BIASINC[4]
(MSB)
BIASINC[3] BIASINC[2] BIASINC[1]
BIASINC[0]
(LSB)
Default Value 0 0 0 0 0 0 0 0
H0x0D
Bit # 7 6 5 4 3 2 1 0 ADDRESS
Name
MODECTRL
[7] (MSB)
MODECTRL
[6]
MODECTRL
[5]
MODECTRL
[4]
MODECTRL
[3]
MODECTRL
[2]
MODECTRL
[1]
MODECTRL
[0] (LSB)
Default Value 0 0 0 0 0 0 0 0
H0x0E
Bit # 7 6 5 4 3 2 1 0 ADDRESS
Name X X X X
SET_
PWCTRL[3]
(MSB)
SET_
PWCTRL[2]
SET_
PWCTRL[1]
SET_
PWCTRL[0]
(LSB)
Default Value X X X X 0 0 0 0
H0x0F