MIC3001GML Micrel Inc, MIC3001GML Datasheet - Page 75

• Manufacturer Part Number: MIC3001GML
• Description: IC FOM MANAGEMENT W/CALIBR 24MLF
• Manufacturer: Micrel Inc
• Type: Transceiverr

Specifications of MIC3001GML

• Protocol: SDHj Sonet
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-MLF®, QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Drivers/receivers: -
• Other names: 576-1753-5; MIC3001GML

Micrel, Inc.
Layout Considerations
Small Form-Factor Pluggable (SFP) Transceivers
The pinout of the MIC3001 digital control and status
signals was optimized for use in small form-factor
pluggable (SFP MSP) optical transceivers. If the
MIC3001 is mounted on the bottom of the PC board with
the correct rotation, the control and status I/O can be
routed to the host connector without changing the order.
This is shown in Figure 36.
Power Supplies
The MIC3001 has separate power supply and ground
pins for both the analog and digital supplies. This helps
prevent digital switching noise from corrupting the
analog functions. The individual supply and ground pins
are not isolated from one another inside the IC.
August 2004
5. In general, wider traces for the ground and T1
Figure 36. Typical SFP Control and Status I/O
Figure 35. Guard Traces and Kelvin Return
measurement of the remote diode’s DVBE, it is
important to adequately clean the PC board after
soldering to prevent current leakage. This is most
likely to show up as an issue in situations where
water-soluble soldering fluxes are used.
lines will help reduce susceptibility to radiated
noise (wider traces are less inductive). Use trace
widths and spacing of 10 mils wherever possible
and provide a ground plane under the MIC3001
and under the connections from the MIC3001 to
the remote diode. This will help guard against
stray noise pickup.
Signal Routing (not to scale)
for Remote Thermal Diode
75
Separate analog and digital power and ground planes
are NOT required on the PCB. Having one of each
plane (power and ground) is certainly good practice,
however. If dedicated power and ground layers are not
available, care should be taken to route the digital
supply and return currents back to the supply separate
from the analog supply connections. A schematic of
this approach is shown in Figure 37. Each supply
should be bypassed as close to the IC as possible with
0.01µF capacitor (Low ESR capacitors such as
ceramics are preferred.) as shown. This assumes that
bulk capacitance is already present upstream. If no
other filter capacitance is present nearby, a 1µF filter
capacitor should be added in parallel to the 0.01µF
capacitor.
Using the MIC3001 In a 5V System
It is fairly straightforward to use the MIC3001 in a
system powered from a 5V rail. In these systems, the
laser diode driver IC will usually be powered from the
5V rail. A small linear regulator, such as Micrel’s
MIC5213, can be used to generate a 3.3V power
supply rail if one does not otherwise exist in the system.
All of the MIC3001’s digital I/O’s except for RSOUT are
5V tolerant and may be pulled up to 5.5V regardless of
the MIC3001’s supply voltage. They can be connected
directly to a 5V host. The MIC5213 is ideal, as it is
capable of supplying up to 80mA, is in a tiny SC-70
package, and is stable with small ceramic output
capacitors.
The laser diode driver interface will be unchanged in
most cases. Ground referred voltages and currents can
be generated the same way as with 3.3V-powerd
drivers. The exception is drivers that are controlled by a
voltage referenced to V
MIC3001’s V
own 3.3V power supply whereas the driver’s input will
be referenced to its 5V power supply. The solution is a
simple level-shifting circuit that converts the V
output into a current and then into a V
voltage.
Figure 37. Power Supply Routing and Bypassing
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