MIC3001GML Micrel Inc, MIC3001GML Datasheet - Page 73

• 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.
Temperature Sensing
The MIC3001 can measure and report its own internal
temperature or the temperature of a remote PN junction or
“thermal diode”. In either case it is important to note that
any board-mounted semiconductor device tends to track
the ground plane temperature around it. The dominant
thermal path to the sensor is often the ground pin. The
ground pin usually connects to the lead-frame paddle on
which the die is mounted. Typical semiconductor packages,
being non-conductive plastic, insulate the device from the
ambient air.
The advantage to using a remote sensor is that the
temperature may be sensed at a specific location, such as
in the proximity of the laser diode, or away from any heat
sources where it will more closely track the transceiver’s
case temperature. The measured temperature is reported
via the digital diagnostics registers and is used to index the
temperature compensation tables. (Note: SFF-8472 does
not specify the meaning of the reported temperature
information or the location from which it is taken. This
information is to be specified in the transceiver vendor’s
datasheet.)
August 2004
Figure 34. Redundant Switch Circuits
73
Remote Sensing
For remote temperature sensing using the XPN pin,
most small-signal PNP transistors with characteristics
similar to the JEDEC 2N3906 will perform well as
thermal diodes. Table 24 lists several examples of
such parts that Micrel has tested for use with the
MIC3001. Other transistors equivalent to these should
also work well.
Minimizing Errors
Self-Heating
One concern when measuring temperature is to avoid
errors induced by self-heating. Self-heating is caused
by power dissipation within the MIC3001. It is directly
proportional to the internal power dissipation and the
junction-to-ambient thermal resistance, θ
dissipation in the MIC3001 must be calculated and
reduced
dissipation, PDISS, includes the effect of quiescent
current and all currents flowing into or out of any
signal
temperature rise caused by self-heating is given by:
θ
as 43°C/W. The possible contributors to self-heating
are listed in Table 25.
The numbers given in Table 25 suggest that the
power dissipation in a typical application will be no
more than a few tens of milliwatts, leading to self-
heating on the order of 1°C.
Vendor
Fairchild Semiconductor
On Semiconductor
Infineon Technologies
Samsung
Semiconductor
JA
is given in the “Operating Ratings” section above
pins,
to
Table 24. Transistors Suitable for
a
especially
Use as Remote Diodes
[e-mail]
temperature
Part Number
MMBT3906
MMBT3906L
SMBT3906/MMBT3906
KST3906-TF
V
BIAS
offset.
and
or [phone]
M9999-082404-A
(14)
The
V
MOD
MIC3001
JA
Package
.
SOT-23
SOT-23
SOT-23
SOT-23
. The
power
The