MAX3646ETG+ Maxim Integrated Products, MAX3646ETG+ Datasheet - Page 8

• Manufacturer Part Number: MAX3646ETG+
• Description: IC LSR DRVR 622MBPS 3.63V 24TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Driver (Fiber Optic)r

Specifications of MAX3646ETG+

• Data Rate: 622Mbps
• Number Of Channels: 1
• Voltage - Supply: 2.97 V ~ 3.63 V
• Current - Supply: 47mA
• Current - Modulation: 85mA
• Current - Bias: 100mA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-TQFN Exposed Pad
• Mounting Type: Surface Mount
• Operating Supply Voltage: 3.3 V
• Supply Current: 47 mA
• Maximum Operating Temperature: + 85 C
• Maximum Power Dissipation: 1805 mW
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

155Mbps to 622Mbps SFF/SFP
Laser Driver with Extinction Ratio Control
Average power is regulated using APC, which keeps
constant current from a photodiode coupled to the
laser. Peak-to-peak power is maintained by compen-
sating the modulation current for reduced slope effi-
ciency (η) of laser over time and temperature:
Modulation compensation from bias increases the mod-
ulation current by a user-selected proportion (K) needed
to maintain peak-to-peak laser power as bias current
Figure 4. Functional Diagram
8
_______________________________________________________________________________________
R
R
BC_MON
PC_MON
TX_DISABLE
SHUTDOWN
TX_FAULT
PC_MON
BC_MON
IN+
IN-
R
PULL
P
P
AVG
I
= 45kΩ
I
BIAS
82
MD
1
P-P
R
= I
TH_TEMP
= η x I
TH_TEMP
MD
T > T
INPUT BUFFER
POWER DETECTOR
/ρ
MOD
SAFETY LOGIC
TH
MON
V
T
CC
AND
R
MODTCOMP
MODTCOMP
xTC
ENABLE
ENABLE
I
I
MOD
BIAS
R
MODSET
MODSET
MAX3646
DATA
PATH
x268
V
MODBCOMP
BG
increases with temperature. Refer to Application Note
1119: HFAN-02.2.1: Maintaining the Extinction Ratio of
Optical Transmitters Using K-Factor Control for details:
This provides a first-order approximation of the current
increase needed to maintain peak-to-peak power.
Slope efficiency decreases more rapidly as tempera-
ture increases. The MAX3646 provides additional tem-
perature compensation as temperature increases past
a user-defined threshold (T
R
xK
MODBCOMP
APCFILT1
I
BIAS
C
APC
APCFILT2
K = ΔI
V
x1/2
CC
I
x1
MOD
APCSET
V
TH
BG
I
MOD
).
/ ΔI
SHUTDOWN
OUT-
OUT+
BIAS
APCSET
MD
BIAS
R
APCSET
R
I
D
BIAS
I
MD
V
C
CC
MD