TMP431 datasheet(13/47 Pages) TI1

13 / 47 page

TMP431, TMP432

www.ti.com

SBOS441G – SEPTEMBER 2009 – REVISED DECEMBER 2015

Table 2. Decimal Fraction Temperature Data Format (Local and Remote Temperature Low Bytes)

TEMPERATURE REGISTER LOW BYTE VALUE (0.0625°C RESOLUTION)(1)

TEMP (°C)

STANDARD AND EXTENDED BINARY

HEX

0000 0000

0.0625

0001 0000

0.1250

0010 0000

0.1875

0011 0000

0.2500

0100 0000

0.3125

0101 0000

0.3750

0110 0000

0.4375

0111 0000

0.5000

1000 0000

0.5625

1001 0000

0.6250

1010 0000

0.6875

1011 0000

0.7500

1100 0000

0.8125

1101 0000

0.8750

1110 0000

0.9375

1111 0000

(1)

Resolution is 0.0625°C/count. All possible values are shown.

8.3.2 Beta Compensation

Previous generations of remote junction temperature sensors were operated by controlling the emitter current of

the sensing transistor. However, examination of the physics of a transistor shows that VBE is actually a function

of the collector current. If beta is independent of the collector current, then VBE may be calculated from the

emitter current. In earlier generations of processors that contained PNP transistors connected to these

temperature sensors, controlling the emitter current provided acceptable temperature measurement results. At

90-nm process geometry and below, however, the beta factor continues to decrease and the premise that it is

independent of collector current becomes less certain.

To manage this increasing temperature measurement error, the TMP43x control the collector current instead of

the emitter current. The TMP43x automatically detect and choose the correct range depending on the beta factor

of the external transistor. This auto-ranging is performed at the beginning of each temperature conversion in

order to correct for any changes in the beta factor as a result of temperature variation. The device can operate a

PNP transistor with a beta factor as low as 0.1. See Beta Compensation Configuration Register for further

information.

8.3.3

Series Resistance Cancellation

Series resistance in an application circuit that typically results from printed circuit-board (PCB) trace resistance

and remote line length is automatically cancelled by the TMP43x, preventing what would otherwise result in a

temperature offset. A total of up to 1-k

Ω of series line resistance is cancelled by the TMP43x if beta correction is

disabled and up to 300

Ω of series line resistance is cancelled if beta correction is enabled, eliminating the need

for additional characterization and temperature offset correction. See Figure 7 and Figure 8 for details on the

effects of series resistance on sensed remote temperature error.

8.3.4 Differential Input Capacitance

The TMP43x can tolerate differential input capacitance of up to 2200 pF with minimal change in temperature

error. The effect of capacitance on sensed remote temperature error is illustrated in Figure 9 and Figure 10. See

Filtering for suggested component values where filtering unwanted coupled signals is needed.

Submit Documentation Feedback

Product Folder Links: TMP431 TMP432

TMP431 Datasheet(PDF) 13 Page - Texas Instruments

TMP431 Datasheet(HTML) 13 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Datasheet Download

Link URL