0.1 F

m

10 kW

(typ)

10 kW

(typ)

10 kW

(typ)

10 kW

(typ)

TMP401

D+

D-

V+

1

8

7

6

4

5

3

2

R

S

(2)

R

S

(2)

C

DIFF

(3)

C

DIFF

(3)

R

S

(2)

R

S

(2)

GND

SCL

SDA

ALERT/THERM2

THERM

+5 V

SMBus

Controller

Fan Controller

Diode-connected configuration :

(1)

Series Resistance

Transistor-connected configuration :

(1)

TMP401

SBOS371B – AUGUST 2006 – REVISED OCTOBER 2014

www.ti.com

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The TMP401 is a remote temperature sensor monitor that includes a built-in local temperature sensor. The

remote temperature sensor diode-connected transistors are typically low-cost, NPN- or PNP-type transistors or

diodes that are an integral part of microcontrollers, microprocessors, or FPGAs.

Remote accuracy is ±1°C for multiple device manufacturers, with no calibration required. The two-wire serial

interface accepts SMBus write, read, send, and receive byte commands to program alarm thresholds and to read

temperature data.

Features included in the TMP401 are series resistance cancellation, wide remote temperature measurement

range (–40°C to +150°C), diode fault detection, and temperature alert functions.

8.2 Typical Application

(1) The diode-connected configuration provides better settling time. The transistor-connected configuration provides better series resistance

cancellation. A 2N3906 PNP is used in this configuration.

(2) In most applications, RS is < 1.5 kΩ.

(3) In most applications, CDIFF is < 1000 pF.

Figure 24. Remote Noise Filtering

8.2.1 Design Requirements

The TMP401 device requires pull-up resistors on the SCL, SDA, ALERT/THERM2, and THERM pins. The

recommended value for the pull-up resistors is 10-k

Ω. A 0.1-μF bypass capacitor on the supply is recommended,

as shown in Figure 24. The SCL and SDA lines can be pulled up to a supply that is equal to or higher than V+

through the pull-up resistors, but not to exceed (V+) + 0.5 V.

28

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