MAX3946ETG+T Maxim Integrated Products, MAX3946ETG+T Datasheet - Page 20

• Manufacturer Part Number: MAX3946ETG+T
• Description: IC LASER DVR SFP 11.3GBPS 24TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driverr

Specifications of MAX3946ETG+T

• Data Rate: 11.3Gbps
• Number Of Channels: 1
• Voltage - Supply: 2.85 V ~ 3.63 V
• Current - Supply: 68mA
• Current - Modulation: 80mA
• Current - Bias: 80mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 12-WFQFN, Exposed Pad
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1.0625Gbps to 11.3Gbps, SFP+ Laser Driver
with Laser Impedance Mismatch Tolerance
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.
Bits 7 to 0: MODECTRL[7:0]. The MODECTRL register enables the user to switch between normal and setup modes.
The setup mode is achieved by setting this register to H0x12. MODECTRL must be updated before each write opera-
tion. Exceptions are MODINC and BIASINC, which can be updated in normal mode.
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.
Bits 5 to 0: SET_TXDE[5:0]. This is a 6-bit register used to control the amount of deemphasis on the transmitter output.
When calculating the total modulation current, the amount of deemphasis must be taken into account. The deemphasis
is set as a percentage of modulation current.
Bits 2 to 1: SET_TXEQ[2:1]. These 2 bits are used to control the amount of equalization on the transmitter input. See
Table 1 for more information.
20
Bit #
Name
Default Value
Bit #
Name
Default Value
Bit #
Name
Default Value
Bit #
Name
Default Value
Bit #
Name
Default Value
_____________________________________________________________________________________
SET_IBIAS
MODECTRL
[0] (LSB)
[7] (MSB)
X
X
7
7
0
7
0
7
X
X
7
X
X
MODECTRL
6
X
X
[6]
6
X
0
6
0
6
X
X
6
X
X
MODECTRL
SET_TXDE
[5] (MSB)
X
X
5
[5]
5
X
0
5
0
5
0
5
X
X
4
X
X
MODECTRL
SET_TXDE
[4] (MSB)
BIASINC
[4]
[4]
4
0
4
0
4
0
4
X
X
SET_PWCTRL
[3] (MSB)
3
0
MODECTRL
SET_TXDE
BIASINC
Bias Current Increment Setting Register (BIASINC)
[3]
[3]
[3]
3
0
3
0
3
0
3
X
X
SET_PWCTRL
Pulse-Width Control Register (SET_PWCTRL)
MODECTRL
SET_TXDE
Equalization Control Register (SET_TXEQ)
SET_TXEQ
Deemphasis Control Register (SET_TXDE)
[2]
BIASINC
2
0
[2]
[2]
[2]
[2]
2
0
2
0
2
0
2
0
Mode Control Register (MODECTRL)
SET_PWCTRL
MODECTRL
SET_TXDE
SET_TXEQ
BIASINC
[1]
1
0
[1]
[1]
[1]
[1]
1
0
1
0
1
0
1
0
SET_PWCTRL
MODECTRL
SET_TXDE
[0] (LSB)
[0] (LSB)
[0] (LSB)
BIASINC
[0] (LSB)
0
0
0
0
0
0
0
1
0
X
X
ADDRESS
ADDRESS
ADDRESS
ADDRESS
ADDRESS
H0x0D
H0x0E
H0x0F
H0x10
H0x11