Remote Diode Temperature (qC)
Mean + 66
±1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
SLOS877B – OCTOBER 2014 – REVISED JUNE 2019
Product Folder Links: TMP451-Q1
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Typical Application (continued)
Figure 20. TMP451-Q1 Remote Diode Temperature Drift
Figure 21. Temperature Step Response
9 Power Supply Recommendations
The TMP451-Q1 device operates with a power supply range of 1.7 V to 3.6 V. The device is optimized for
operation at 3.3-V supply but can measure temperature accurately in the full supply range.
A power-supply bypass capacitor is recommended. Place this capacitor as close as possible to the supply and
ground pins of the device. A typical value for this supply bypass capacitor is 0.1 μF. Applications with noisy or
high-impedance power supplies may require additional decoupling capacitors to reject power-supply noise.
10.1 Layout Guidelines
Remote temperature sensing on the TMP451-Q1 device measures very small voltages using very low currents;
therefore, noise at the device inputs must be minimized. Most applications using the TMP451-Q1 have high
digital content, with several clocks and logic level transitions creating a noisy environment. Layout should adhere
to the following guidelines:
1. Place the TMP451-Q1 device 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 through the use of
ground guard traces; see Figure 22. If a multilayer PCB is used, bury these traces between ground or V+
planes to shield them from extrinsic noise sources. 5 mil (0.127 mm) 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 TMP451-Q1 device. For
optimum measurement performance, minimize filter capacitance between D+ and D– to 1000 pF or less .
This capacitance includes any cable capacitance between the remote temperature sensor and the TMP451-
5. If the connection between the remote temperature sensor and the TMP451-Q1 device is less than 8-in (20,32
cm) long, use a twisted-wire pair connection. For lengths greater than 8 in, use a twisted, shielded pair with
the shield grounded as close to the TMP451-Q1 device as possible. Leave the remote sensor connection
end of the shield wire open to avoid ground loops and 60-Hz pickup.
6. Thoroughly clean and remove all flux residue in and around the pins of the TMP451-Q1 device to avoid
temperature offset readings as a result of leakage paths between D+ and GND, or between D+ and V+.