TMP411CD datasheet(44/61 Pages) TI2

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9.3 Power Supply Recommendations

The TMP411 operates with a power supply range of 2.7V to 5.5V while TMP411D power supply range is 1.62V

to 5.5V. The device is optimized for operation at a 3.3V supply, but measures temperature accurately in the full

supply range. TI recommends using a power supply bypass capacitor. Place the capacitor as close as possible

to the supply and ground pins of the device. 0.1µF is a typical value for the supply bypass capacitor. Applications

with noisy or high-impedance power supplies can require additional decoupling capacitors to reject power-supply

noise.

9.4 Layout

9.4.1 Layout Guidelines

Remote temperature sensing on the TMP411/TMP411D measures small voltages using low currents, and

therefore noise at the device inputs must be minimized. Most applications using the TMP411/TMP411D have

high digital content with several clocks and logic-level transitions that create a noisy environment. The layout

must adhere to the following guidelines:

• Place the TMP411/TMP411D as close to the remote junction sensor as possible.

• Route the D+ and D– traces next to each other and shield the traces from adjacent signals using ground

guard traces, as shown in Figure 9-10. If a multilayer PCB is used, bury these traces between ground or VDD

planes to shield the planes from extrinsic noise sources. TI recommends using 5mm (0.127mm) PCB traces.

• Minimize additional thermocouple junctions caused by copper-to-solder connections. If these junctions are

used, make the same number and approximate location of copper-to-solder connections in the D+ and D–

connections to cancel any thermocouple effects.

• Use a 0.1µF local bypass capacitor directly between the V+ and GND pins of the TMP411/TMP411D,

as shown in Figure 9-11. Minimize filter capacitance between D+ and D– to 1000pF or less for

optimum measurement performance. This capacitance includes any cable capacitance between the remote

temperature sensor and the TMP411/TMP411D.

• If the connection between the remote temperature sensor and the TMP411/TMP411D is less than eight

inches (20cm), use a twisted-wire pair connection. If the connection measures more than eight inches

(20cm), use a twisted, shielded pair with the shield grounded as close to the TMP411/TMP411D as possible.

Leave the remote sensor connection end of the shield wire open to avoid grounded loops and 60Hz pickup.

GND

D+

Dí

GND

Ground or V+ layer

on bottom and/or

top, if possible.

Figure 9-10. Example Signal Traces

TMP411, TMP411D

SBOS383E – DECEMBER 2006 – REVISED JULY 2025

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TMP411CD Datasheet(PDF) 44 Page - Texas Instruments