DESCRIPTION

The NE1618 is an accurate two-channel temperature monitor. It measures the temperature of itself and the temperature of a remote sensor. It can replace the NE1617 for a more precise measurement to the remote temperature when it operates in extended mode. The remote sensor is a diode connected transistor being in the form of either a discrete NPN/PNP, such as the 2N3904/2N3906, or a diode connected PNP built into another die, such as is done on some INTEL microprocessors.

The temperature of both the remote and local sensors are stored in the registers that can be read via a 2-wire SMBus. The data in the temp reading registers are updated at the end of every data conversion when the conversion is enable. At all time, data conversion is initiated automatically in the rate defined by the programmable data in the conversion rate register. However, a conversion can be forced to occur immediately by a one-shot programming.

The local temp is always measured with a resolution of 1.0 °C but the remote temp can be measured in either one of two modes: extended mode with a resolution of 0.125 °C and basic mode with a resolution of 1.0 °C. The mode is set up automatically according to the programmable data stored in the conversion rate register. (See Table 6). Extended mode is set when the conversion rate is slow (rate 0.7 Hz or less) and normal mode is set when the rate is high (conversion rate of 2, 4, or 8 Hz).

FEATURES

• Monitors local and remote temperature

• Accuracy

– ± 2 °C local (on-chip) sensor

– ± 1.5 °C remote sensor with 1 °C resolution

– ± 1.0 °C remote sensor with 0.125 °C resolution

• No calibration required

• Programmable over/under temperature alarm

• SMBus 2-wire serial interface

• 3 V to 3.6 V supply range

• 80 µA supply current in operating mode

• 3 µA (typical) supply current in standby mode

• Small 16-lead QSOP package

APPLICATIONS

• Desktop computers

• Notebook computers

• Smart battery packs

• Industrial controllers

• Telecom equipment