MAX3946ETG+T Maxim Integrated Products, MAX3946ETG+T Datasheet

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MAX3946ETG+T

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

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
19-5182; Rev 0; 3/10
The MAX3946 is a +3.3V, multirate, low-power laser
diode driver designed for Ethernet and Fibre Channel
transmission systems at data rates up to 11.3Gbps.
This device is optimized to drive a differential transmit-
ter optical subassembly (TOSA) with a 25I flex circuit.
The unique design of the output stage enables use of
unmatched TOSAs, greatly reducing headroom limita-
tions and lowering power consumption.
The device receives differential CML-compatible signals
with on-chip line termination. It can deliver laser modula-
tion current of up to 80mA, at an edge speed of 20ps
(20% to 80%), into a 5I to 25I external differential load.
The device is designed to have a symmetrical output
stage with on-chip back terminations integrated into
its outputs. A high-bandwidth, fully differential signal
path is implemented to minimize deterministic jitter. An
equalization block can be activated to compensate for
the SFP+ connector. The integrated bias circuit provides
programmable laser bias current up to 80mA. Both the
laser bias generator and the laser modulator can be dis-
abled from a single pin, DISABLE.
A 3-wire digital interface reduces the pin count and
permits adjustment of input equalization, pulse-width
adjustment, Tx polarity, Tx deemphasis, modulation cur-
rent, and bias current without the need for external com-
ponents. The MAX3946 is available in a 4mm x 4mm,
24-pin TQFN package.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
4x/8x FC SFP+ Optical Transceivers
10GFC SFP+ Optical Transceivers
10GBASE-LR SFP+ Optical Transceivers
10GBASE-LRM SFP+ Optical Transceivers
OC192-SR XFP/SFP+ Transceivers
1.0625Gbps to 11.3Gbps, SFP+ Laser Driver
with Laser Impedance Mismatch Tolerance
_______________________________________________________________ Maxim Integrated Products 1
General Description
Applications
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
Note: Parts are guaranteed by design and characterization to
operate over the -40°C to +95°C ambient temperature range
(T
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
MAX3946ETG+
A
225mW Power Dissipation Enables < 1W SFP+
Modules
Up to 100mW Power Consumption Reduction by
Enabling the Use of Unmatched FP/DFB TOSAs
Supports SFF-8431 SFP+ MSA and SFF-8472
Digital Diagnostic
225mW Power Dissipation at 3.3V (I
I
Single +3.3V Power Supply
Up to 11.3Gbps (NRZ) Operation
Programmable Modulation Current from 10mA to
100mA (5I Load)
Programmable Bias Current from 5mA to 80mA
Programmable Input Equalization
Programmable Output Deemphasis
25I Output Back Termination at TOUT+ and
TOUT-
DJ Performance 7ps
Differential Load (5I)
DJ Performance 5ps
Differential Load (25I)
DJ Performance 5ps
Programmable Pulse Width
Edge Transition Times of 20ps
Bias Current Monitor
Integrated Eye Safety Features
3-Wire Digital Interface
-40°C to +95°C Operation
) and are tested up to +85°C.
BIAS
PART
= 60mA Assuming 25I TOSA)
-40°C to +85°C
TEMP RANGE
Ordering Information
P-P
P-P
P-P
with Mismatched
with Mismatched
with 50I Differential Load
PIN-PACKAGE
MOD
24 TQFN-EP*
Features
= 40mA,

Related parts for MAX3946ETG+T

MAX3946ETG+T Summary of contents

Page 1

... SFP+ Optical Transceivers 10GBASE-LR SFP+ Optical Transceivers 10GBASE-LRM SFP+ Optical Transceivers OC192-SR XFP/SFP+ Transceivers _______________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 225mW Power Dissipation Enables < 1W SFP+ ...

Page 2

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance ABSOLUTE MAXIMUM RATINGS ................................................-0.3V to +4.0V CC CCT CCD Current Into TOUT+ and TOUT- .................................... +100mA Current Into TIN+ and TIN- ............................. -20mA to ...

Page 3

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance ELECTRICAL CHARACTERISTICS (continued +2.85V to +3.63V -40°C to +85°C, and Figure 1. Guaranteed by design and characterization from Typical values are at ...

Page 4

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance ELECTRICAL CHARACTERISTICS (continued +2.85V to +3.63V -40°C to +85°C, and Figure 1. Guaranteed by design and characterization from Typical values are at ...

Page 5

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance ELECTRICAL CHARACTERISTICS (continued +2.85V to +3.63V -40°C to +85°C, and Figure 1. Guaranteed by design and characterization from Typical values are at ...

Page 6

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance 4.7kI EET 0.01µF 0.01µ 50I TIN+ 0 0.01µF TIN 50I 0.01µF V EET ...

Page 7

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance (V = +3.3V +25°C, data pattern = 10.3Gbps OPTICAL EYE DIAGRAM INPUT DIFFERENTIAL RETURN LOSS vs. FREQUENCY 0 -5 -10 -15 -20 -25 -30 ...

Page 8

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance (V = +3.3V +25°C, data pattern = SUPPLY CURRENT vs. TEMPERATURE (I = 40mA , I = 60mA) MOD P-P BIAS 100 CURRENT INTO ...

Page 9

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance (V = +3.3V +25°C, data pattern = TRANSMITTER DISABLE MAX3946 toc18 V CC 3.3V LOW FAULT HIGH DISABLE LOW OUTPUT 100ns/div FAULT RECOVERY V ...

Page 10

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance TOP VIEW *EXPOSED PAD CONNECTED TO GROUND. PIN NAME Power Supply. Provides supply voltage to the digital block. CCD Disable Input, CMOS Input. Set to logic-low ...

Page 11

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance PIN NAME 18 SCL Serial-Clock Input, CMOS. This pin has 75kI internal pulldown. 19 Ground EET 20 Power-Supply Connections. Provides supply voltage to the core ...

Page 12

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Detailed Description The MAX3946 SFP+ laser driver is designed to drive 5I to 50I lasers from 1Gbps to 11.3Gbps. The device contains an input buffer with programmable equaliza- tion, ...

Page 13

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance V CC MAX3946 + 0.6V - WARNING 100kI FAULT 1.2V Figure 3. BMON and BMAX Circuitry After initialization the value of the SET_IMOD DAC reg- ister should be updated ...

Page 14

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance BIAS I BIAS BMAX I BIAS 100 BMON V CC 7.5kI DISABLE LOSS-OF-SIGNAL CIRCUIT Figure 4. Eye Safety Circuitry 14 _____________________________________________________________________________________ FAULT REGISTERS MOD 0.44V V ...

Page 15

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Table 2. Circuit Response to Single-Point Faults PIN NAME SHORT Normal CCD 2 DISABLE Disabled 3 FAULT Normal (Note 1) 4 BMAX Disabled—HARD FAULT 5 ...

Page 16

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance The device implements a proprietary 3-wire digital inter- face. An external controller generates the clock. The 3-wire interface consists of an SDA bidirectional data line, an SCL clock signal ...

Page 17

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance WRITE MODE CSEL SCL SDA READ MODE CSEL SCL ...

Page 18

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance 7 6 Bit # (STICKY) (STICKY) Name FST[7] FST[6] Default Value X X Bit 7: FST[7]. When the V supply voltage is below 2.3V, the POR circuitry reports a ...

Page 19

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Bit # 7 6 SET_IMOD SET_IMOD Name [8] (MSB) [7] Default Value 0 0 Bits SET_IMOD[8:1]. The modulation current DAC is controlled by a total of ...

Page 20

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Bit # 7 6 SET_IBIAS Name X [0] (LSB) Default Value 0 0 Bit 7: SET_IBIAS[0]. This is the LSB of the SET_IBIAS[8:0] bits. This bit can only be ...

Page 21

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Design Procedure Programming Bias Current 1) IBIASMAX[7:0] = Maximum_Bias_Current_Value 2) SET_IBIAS [8:1] = Initial_Bias_Current_Value i Note: The total bias current is calculated using the SET_IBIAS[8:0] DAC value. SET_IBIAS[8:1] are ...

Page 22

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Programming Pulse-Width Control The eye crossing at the Tx output can be adjusted using the SET_PWCTRL register. Table 5 shows these set- tings. The sign of the number specifies ...

Page 23

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Table 6. Register Summary (continued) REGISTER REGISTER NORMAL FUNCTION/ NAME MODE ADDRESS Transmitter Status Register 2 TXSTAT2 Address = H0x07 Bias Current Setting Register SET_IBIAS Address = H0x08 Accessible ...

Page 24

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance Table 6. Register Summary (continued) REGISTER REGISTER NORMAL FUNCTION/ NAME MODE ADDRESS Modulation RW Current Increment MODINC RW Setting Register RW Address = RW H0x0C RW Bias Current RW ...

Page 25

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance V CCT TIN+ 50I 50I TIN- V CCT 7.5kI DISABLE V EET Figure 6. Simplified I/O Structures Layout Considerations The data inputs and outputs are the most critical paths ...

Page 26

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance HOST BOARD SFP CONNECTOR HOST FILTER 100I DIFF FR4 MICROSTRIP UP TO 5.5in V CC 4.7kI TO 10kI TX_FAULT TX_DISABLE RATE SELECT MODE_DEF1 (SCL) MODE_DEF2 ...

Page 27

SFP+ Laser Driver with Laser Impedance Mismatch Tolerance HOST BOARD SFP CONNECTOR HOST FILTER 100I DIFF FR4 MICROSTRIP UP TO 5.5in V CC 4.7kI TO 10kI TX_FAULT RATE SELECT TX_DISABLE MODE_DEF1 (SCL) MODE_DEF2 ...

Page 28

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 28 2010 Maxim Integrated Products © ...

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