TMP411D datasheet(44/60 Pages) TI2

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9.3 Power Supply Recommendations

The TMP411-Q1 operates with a power supply range of 2.7V to 5.5V, while the TMP411D-Q1 power supply

range of 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-Q1 and TMP411D-Q1 devices measures small voltages using low

currents, and therefore, noise at the device inputs must be minimized. Most applications using the TMP411-Q1

and TMP411D-Q1 devices have high digital content, with several clocks and logic-level transitions creating a

noisy environment. The layout must adhere to the following guidelines:

1. Place the TMP411-Q1 and TMP411D-Q1 devices as close to the remote junction sensor as possible.

2. Route the D+ and D− traces next to each other and shield them 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 them from extrinsic noise sources. Five-mil (0.127mm) PCB traces are recommended.

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

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

D− connections to cancel any thermocouple effects.

4. Use a 0.1μF local bypass capacitor directly between the V+ and GND of the TMP411-Q1 and TMP411D-Q1

devices, 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-Q1 and TMP411D-Q1 devices.

5. If the connection between the remote temperature sensor and the TMP411-Q1 and TMP411D-Q1 devices

is less than 8 inches (20cm), use a twisted-wire pair connection. Beyond 8 inches (20cm), use a twisted,

shielded pair with the shield grounded as close to the TMP411-Q1 and TMP411D-Q1 devices as possible.

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

–(A)

(A)

5mil (0.127mm) traces with 5mil (0.127mm) spacing

Figure 9-10. Example Signal Traces

TMP411-Q1, TMP411D-Q1

SBOS527G – DECEMBER 2010 – REVISED SEPTEMBER 2025

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