TMP141AIDBVT datasheet(7/22 Pages) TI2

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TMP141

SBAS347A − MARCH 2005 − REVISED JULY 2006

www.ti.com

OVERVIEW

The TMP141 is a digital output temperature sensor that

uses the single-wire SensorPath interface protocol. It does

not require any external sensing components for

measuring temperature. In order to minimize circuit board

space, the TMP141 is offered in the MSOP-8 and

SOT23-6 packages.

The primary usage of SensorPath-based systems is for

systems that monitor hardware health. The predefined

SensorPath functions are: temperature measurement,

voltage measurement, and non-volatile memory. The

specification allows for expansion by defining new

functions or enlarging upon the predefined functions. The

TMP141 implements the temperature measurement

function with a resolution of 0.25

°C.

The SensorPath interface allows a master to read up to

seven slave devices on a bus, four of which can be

TMP141s. The master interrogates devices on the bus to

determine what they are, their capabilities, and how they

can be used. Devices on the Single-Wire Data (SWD) bus

are open drain. Therefore, the SWD bus requires a 1.25k

Ω

pull-up resistor on the bus. This resistor may be provided

by the master. If the pull-up resistor is not included within

the master, an external resistor must be attached to the

bus. A 0.1

µF capacitor is recommended for power-supply

bypassing, as shown in Figure 3. Registers inside each

device include information that identifies the device

capabilities, manufacturer, part ID, and even device

revision number.

TMP141

Master

Optional

R = 1.25k

Ω

SWD

ADD1

ADD0

S =3.3V

0.1

µF

The resistor R may be

integrated into the master.

Figure 3. Typical Connections of the TMP141

TEMPERATURE SENSING AND

CONVERSION

The TMP141 senses the absolute temperature by utilizing

a diode which is part of the IC. Therefore, the sensing

device of the TMP141 is the chip itself. Thermal paths run

through the package leads as well as the plastic package,

and the lower thermal resistance of metal causes the leads

to provide the primary thermal path.

To maintain accuracy in applications that require air or

surface temperature measurement, care should be taken

that the package and leads thermally connect with the

surface where the temperature measurement is desired.

For example, a thermally-conductive adhesive assists in

achieving accurate surface temperature measurements.

Even without special precautions, because of the very low

power consumption of the TMP141, self-heating will

normally be well below 1LSB (0.25

°C).

TYPICAL APPLICATION

The TMP141 is normally used with the address pins wired

high or low to select one of four possible addresses. The

value read from the hardware pins plus one is stored in

transmits a matching device number, the TMP141 will

respond. In the example shown in Figure 3, ADD1:ADD0

are wired to 2h. In this example, 3h will be stored in register

0. When the master addresses device number 3, the

TMP141 in Figure 3 will respond. The TMP141 will also

work well in applications where ADD0:ADD1 are driven by

logic levels since it reads these pins every time it does a

conversion or bus transaction (see Table 2).

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