THMC10

Two-Wire SMBus Serial Interface
On-Chip and External Diode-Connected Transistor Temperature Monitoring
±2.5°C Accuracy for On-Die
±3°C Accuracy for External
Programmable Under/Overtemperature Limits
Under/Overtemperature Interrupt Signal to Host Controller
Low Operating Current . . . 35 mA (Average)
Low Standby Current . . . 3 mA
3-V to 3.6-V Supply Voltage Range

Input voltage on: V_DD supply terminal, V_(DDIN) . . . . . . . . . . . . . . . . . . . . 0.3 V to 6 V
I/O terminals, V_(IOIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to V_DD + 0.3 V
SMBus terminals, V_(SMBIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.3 V to 6 V
DXN terminal, V_(DXN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to 0.8 V
SMBus input/output current, I_(SMBIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 mA to 50 mA
DXN input current, I_(DXN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mA to 1 mA
Continuous power dissipation, P_D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 mW
Operating case temperature range, T_C . . . . . . . . . . . . . . . . . . . . . . . . . . 55°C to 125°C
Storage temperature, T_stg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65°C to 165°C
Junction temperature, T_J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150°C
Lead temperature (soldering, 10 sec), T_(LEAD) . . . . . . . . . . . . . . . . . . . . .300°C

The THMC10 is a dual digital temperature monitor with under/overtemperature alerts intended for use in personal computer systems or any other system requiring local as well as remote temperature monitoring and management (e.g., servers and workstations). The device may be used in smart battery applications and memory modules. The THMC10 is designed to measure the temperature on a microprocessor using a diode-connected transistor on the microprocessor die, such as the one present on the Intel) Pentium) II, III, and the Sun) UltraSPARCE. The THMC10 may also be used with a low-cost, diode-connected, discrete transistor, such as a 2N3904 or 2N3906, for remote temperature sensing applications.

The THMC10 uses a two-current measurement technique on a single diode-connected transistor that cancels the absolute value of the remote transistor's V_BE; therefore, no calibration is needed. The second channel measures an on-chip temperature sensor which can be used to monitor the ambient temperature in the THMC10's operating environment.

The THMC10 uses a two-wire, SMBus interface to report temperature in an 8-bit, 2s complement format in °C. Under/overtemperature limits for both the on-chip and remote temperature sensors are user programmable via the SMBus interface. TheALERT terminal of THMC10 can be used as an interrupt or SMBus alert function to indicate under/overtemperature. The STBY terminal and the start/stop bit in the SMBus interface allow the device to enter a low current standby mode (typically <10 mA).

The THMC10 also provides diagnostics via the ALERT terminal and the SMBus interface for an open remote sensor connection or if the sensor connection is shorted to V_DD.