TMP112DX datasheet(28/46 Pages) TI1

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8.2.1 Design Requirements

The TMP112 family requires pullup resistors on the SCL, SDA, and ALERT pins. The recommended value for

the pullup resistors is 5kΩ. In some applications the pullup resistor can be lower or higher than 5kΩ but must

not exceed 3mA of current on any of those pins. A 0.01-μF bypass capacitor on the supply is recommended as

shown in Figure 8-1 and Figure 8-2. The SCL and SDA lines can be pulled up to a supply that is equal to or

higher than V+ through the pullup resistors. To configure one of four different addresses on the bus, connect the

ADD0 pin to either the GND, V+, SDA, or SCL pin. The TMP112Dx also provides four different address options

when only ALERT pin is used.

8.2.2 Detailed Design Procedure

Place the device in close proximity to the heat source that must be monitored, with a proper layout for good

thermal coupling. This placement verifies that temperature changes are captured within the shortest possible

time interval. To maintain accuracy in applications that require air or surface temperature measurement, take

care to isolate the package and leads from ambient air temperature. A thermally-conductive adhesive is helpful

in achieving accurate surface temperature measurement.

The TMP112 family is a very low-power device and generates very low noise on the supply bus. Applying an

RC filter to the V+ pin of the TMP112 family can further reduce any noise that the device can propagate to other

components. R(F) in Figure 8-3 must be less than 5 kΩ and C(F) must be greater than 10 nF.

Device

SCL

SDA

GND

V+

ALERT

ADD0

(F)

10 nF

≥

(F)

5 k

≤

Supply Voltage

Figure 8-3. Noise Reduction Techniques (for SOT563-6 package as an example)

8.2.3 Application Curve

Figure 8-4 shows the step response of the TMP112 to a submersion in an oil bath of 100ºC from room

temperature (25ºC). The time-constant, or the time for the output to reach 63% of the input step, is around 1.2s

for both packages. The time-constant result depends on the printed-circuit board (PCB) size that the TMP112 is

mounted. For this test, the TMP112 is soldered to a two-layer PCB that measured 0.5 inches × 0.5 inches.

TMP112, TMP112D

SBOS473L – MARCH 2009 – REVISED JULY 2024

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