LM63CIMA National Semiconductor, LM63CIMA Datasheet - Page 27

• Manufacturer Part Number: LM63CIMA
• Manufacturer: National Semiconductor

Specifications of LM63CIMA

• Temperature Sensor Function: Temp Sensor
• Interface Type: Serial (2-Wire)
• Output Type: Digital
• Package Type: SOIC N
• Operating Temperature (min): 0C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Lead Free Status / Rohs Status: Not Compliant

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short and identical as possible. Trace resistance of 1 Ω
can cause as much as 1°C of error. This error can be
compensated by using the Remote Temperature Offset
Registers, since the value placed in these registers will
automatically be subtracted from or added to the remote
temperature reading.
Diode traces should be surrounded by a GND guard ring
to either side, above and below if possible. This GND
guard should not be between the D+ and D− lines. In the
event that noise does couple to the diode lines it would
be ideal if it is coupled common mode. That is equally to
the D+ and D− lines.
Avoid routing diode traces in close proximity to power
supply switching or filtering inductors.
Avoid running diode traces close to or parallel to high
speed digital and bus lines. Diode traces should be kept
at least 2 cm apart from the high speed digital traces.
If it is necessary to cross high speed digital traces, the
diode traces and the high speed digital traces should
cross at a 90 degree angle.
The ideal place to connect the LM63's GND pin is as
close as possible to the Processor's GND associated
with the sense diode.
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Noise coupling into the digital lines greater than 400 mVp-p
(typical hysteresis) and undershoot less than 500 mV below
GND, may prevent successful SMBus communication with
the LM63. SMBus no acknowledge is the most common
symptom, causing unnecessary traffic on the bus. Although
the SMBus maximum frequency of communication is rather
low (100 kHz max), care still needs to be taken to ensure
proper termination within a system with multiple parts on the
bus and long printed circuit board traces. An RC lowpass filter
with a 3 dB corner frequency of about 40 MHz is included on
the LM63's SMBCLK input. Additional resistance can be
added in series with the SMBData and SMBCLK lines to fur-
ther help filter noise and ringing. Minimize noise coupling by
keeping digital traces out of switching power supply areas as
well as ensuring that digital lines containing high speed data
communications cross at right angles to the SMBData and
SMBCLK lines.
Leakage current between D+ and GND should be kept
to a minimum. One nano-ampere of leakage can cause
as much as 1°C of error in the diode temperature reading.
Keeping the printed circuit board as clean as possible will
minimize leakage current.
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