1FEATURES

• Accurately Senses Die Temperature of Remote

ICs or Diode Junctions

• Offset Register Allows Sensing a Variety of

Thermal Diodes Accurately

• On-board Local Temperature Sensing

• 10 Bit Plus Sign Remote Diode Temperature

Data Format, 0.125°C Resolution

• Diode Fault Detection Circuitry

• T_CRIT_A Output Useful for System Shutdown

(Open Diode does not Activate T_CRIT_A)

• ALERT Output Supports SMBus 2.0 Protocol

• SMBus 2.0 Compatible Interface, Supports

TIMEOUT

• 8-pin VSSOP Package

APPLICATIONS

• System Thermal Management

(e.g. Laptop, Desktop, Workstations, Server)

• Electronic Test Equipment

• Office Electronics

KEY SPECIFICATIONS

• Supply Voltage 3.0 to 3.6 V

• Supply Current 0.8 mA (Typ)

• Local Temp Accuracy (Includes Quantization

Error)

– TA=25°C to 125°C, ±4.0 °C (Max)

• Remote Diode Temp Accuracy (Includes

Quantization Error)

– TA=30°C to 50°C, TD=60°C to 100°C, ±3.0 °C

(Max)

– TA=0°C to 85°C, TD=25°C to 125°C, ±4.0 °C

(Max)

DESCRIPTION

The LM90 is an 11-bit digital temperature sensor with

a 2-wire System Management Bus (SMBus) serial

interface. The LM90 accurately measures its own

temperature as well as the temperature of an external

device, such as processor thermal diode or diode

connected transistor such as the 2N3904. The

temperature of any ASIC can be accurately

determined using the LM90 as long as a dedicated

diode (semiconductor junction) is available on the

target die. The LM90 remote sensor accuracy of ±3°C

is factory trimmed for the 1.008 typical non-ideality

factor of the mobile Pentium III thermal diode. The

LM90 has an Offset register to allow measuring other diodes without requiring continuous software

management.

Activation of the ALERT output occurs when any

temperature goes outside a preprogrammed window

set by the HIGH and LOW temperature limit registers

or exceeds the T_CRIT temperature limit. Activation

of the T_CRIT_A occurs when any temperature

exceeds the T_CRIT programmed limit. The LM90 is

pin and register compatible with the LM86, Analog

Devices ADM1032 and Maxim MAX6657/8.