MIC281 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – Low-Cost IttyBitty Thermal Sensor IttyBitty

MIC281
Micrel
MIC281
Low-Cost IttyBitty™ Thermal Sensor IttyBitty®
REV 11/04
General Description
The MIC281 is a digital thermal sensor capable of measuring
the temperature of a remote PN junction. It is optimized for
applications favoring low cost and small size. The remote
junction may be an inexpensive commodity transistor, e.g.,
2N3906, or an embedded thermal diode such as found in
Intel Pentium* II/III/IV CPUs, AMD Athlon* CPUs, and Xilinx
Virtex* FPGAs.
The MIC281 is 100% software and hardware backward com-
patible with the MIC280 and features the same industry-leading
noise performance and small size. The advanced integrating
A/D converter and analog front-end reduce errors due to noise
for maximum accuracy and minimum guardbanding.
A 2-wire SMBus 2.0-compatible serial interface is provided for
host communication. The clock and data pins are 5V-tolerant
regardless of the value of V_DD. They will not clamp the bus
lines low even if the device is powered down.
Superior performance, low power, and small size make the
MIC281 an excellent choice for cost-sensitive thermal man-
agement applications.
Features
• Remote temperature measurement using embedded
thermal diodes or commodity transistors
• Accurate remote sensing
±3°C max., 0°C to 100°C
• Excellent noise rejection
• I²C and SMBus 2.0 compatible serial interface
• SMBus timeout to prevent bus lockup
• Voltage tolerant I/Os
• Low power shutdown mode
• Failsafe response to diode faults
• 3.0V to 3.6V power supply range
• IttyBitty™ SOT23-6 Package
Applications
• Desktop, server and notebook computers
• Set-top boxes
• Game consoles
• Appliances
Typical Application
3.3V
TO
SERIAL BUS
HOST
10k
pull-ups
MIC281
5 _DATA
4 _CLK
NC
VDD ¹
T1 ³
GND ²
0.1µF
2000pF
CPU DIODE
MIC281 Typical Application
IttyBitty is a registered trademark of Micrel, Inc.
*All trademarks are the property of their respective owners.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
November 2004
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MIC281