Philips Semiconductors

Product data

NE1618

Temperature monitor for microprocessor systems

2

2002 Jan 04

853–2299 27510

FEATURES

–

± 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

APPLICATIONS

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).

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).

PIN CONFIGURATION

9

10

11

12

13

14

15

16

1

2

3

4

5

6

7

8

TEST1

D+

D–

TEST5

ADD1

GND

GND

TEST16

STBY

SCLK

TEST13

SDATA

ALERT

ADD0

TEST9

SL01238

NE1618

Figure 1. Pin configuration

PIN DESCRIPTION

PIN #

FUNCTION

DESCRIPTION/COMMENTS

1

TEST1

2

3

D+

Positive side of remote sensor

4

D–

Negative side of remote sensor

5

TEST5

6

ADD1

Device address pin (3-State)

7

GND

Ground

8

GND

Ground

9

TEST9

10

ADD0

Device address pin (3-State)

11

ALERT

Open drain output used as

interrupt or SMBus alert

12

SDATA

SMBus serial data input/output

open drain

13

TEST13

14

SCLK

SMBus clock input

15

STBY

Hardware standby input pin

HIGH = normal operating mode

LOW = standby mode

16

TEST16

NOTES:

1. These pins should either floating or be tied to ground.

ORDERING INFORMATION

PART NUMBER

PACKAGE

DRAWING NUMBER

NE1618DS

SOT519–1

NOTE:

1. Also called “SSOP16”.