MAX3795ETG Maxim Integrated Products, MAX3795ETG Datasheet - Page 13

• Manufacturer Part Number: MAX3795ETG
• Description: Laser Driver 1Gbps to 4.25Gbps Mu ltirate VCSEL Driver
• Manufacturer: Maxim Integrated Products
• Type: Transmitterr

Specifications of MAX3795ETG

• Operating Supply Voltage: 3.3 V
• Package / Case: TQFN-24 EP
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT

The low frequency cutoff of a transmitter using APC is
given by:
The MAX3795 data inputs are SFP MSA compatible. On-
chip, 100Ω differential input impedance is provided for
optimal termination (Figure 4). Because of the on-chip
biasing network, the MAX3795 inputs self-bias to the
proper operating point to accommodate AC-coupling.
Figure 5. Simplified Output Structure
Figure 6. Fault Circuit Interface
I
f
PD
3
dB
50W
=
≈
V
∆
REF
R
∆
I
PWRSET
LASER
I
PD
1Gbps to 4.25Gbps Multirate VCSEL Driver
50W
−
Input Termination Requirements
MAX3795
V
MD
×
______________________________________________________________________________________
2
≈
×
R
π
V
PWRSET
CC
0 2 .
×
C
1
V
APC
V
×
CC
50
PACKAGE
MAX3795
0.5pF
0.5pF
1nH
1nH
FAULT
OUT+
OUT-
with Diagnostic Monitors
Figures 4 and 5 show simplified input and output circuits
for the MAX3795 laser driver. Figure 6 shows the fault cir-
cuit interface.
To minimize inductance, keep the connections between
the MAX3795 output pins and laser diode as short as
possible. Use multilayer boards with uninterrupted
ground planes to minimize EMI and crosstalk.
The exposed pad on the 24-pin thin QFN provides a very
low thermal resistance path for heat removal from the IC.
The pad is also electrical ground on the MAX3795 and
must be soldered to the circuit board ground for proper
thermal and electrical performance. Refer to Maxim
Application Note HFAN-08.1: Thermal Considerations for
QFN and Other Exposed-Pad Packages for additional
information.
The International Electrotechnical Commission (IEC)
determines standards for hazardous light emissions from
fiber-optic transmitters. IEC 825 defines the maximum
light output for various hazard levels. The MAX3795 pro-
vides features that facilitate compliance with IEC 825. A
common safety precaution is single-point fault tolerance,
whereby one unplanned short, open, or resistive connec-
tion does not cause excess light output. Using this laser
driver alone does not ensure that a transmitter design is
compliant with IEC 825. The entire transmitter circuit and
component selections must be considered. Customers
must determine the level of fault tolerance required by
their applications, recognizing that Maxim products are
not designed or authorized for use as components in
systems intended for surgical implant into the body, for
applications intended to support or sustain life, or for any
other application where the failure of a Maxim product
could create a situation where personal injury or death
may occur.
Applications Information
Exposed-Pad (EP) Package
Laser Safety and IEC 825
Layout Considerations
Interface Models
13