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 1.0C but the remote temp can be measured in either one of two modes: extended mode with a resolution of 0.125C and basic mode with a resolution of 1.0C. The mode is set up automatically according to the programmable data stored in the conversion rate register. 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).
There is also an alarm that senses either an over or under temperature condition. The trip points for this alarm are also programmable. The device can have 1 of 9 addresses (determined by 2 address pins), so there can be up to 9 of the NE1618 on the
SMBus. It can also be put in a standby mode (in order to save power). This can be done either with software (over the SMBus) or with hardware (using the STBY pin).