9.3 Power Supply Recommendations

The TMP461-EP device operates with a power-supply range of 1.7V to 3.6V. The device is optimized for

operation at a 3.3V 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 0.1μF. 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 TMP461-EP device measures very small voltages using very low currents;

therefore, noise at the device inputs must be minimized. Most applications using the TMP461-EP have high

digital content, with several clocks and logic-level transitions that create a noisy environment. Layout must

adhere to the following guidelines:

1. Place the TMP461-EP 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, as shown in Figure 9-5. If a multilayer PCB is used, bury these traces between

the ground or V+ planes to shield them from extrinsic noise sources. 5mil (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 TMP461-EP device. For

optimum measurement performance, minimize filter capacitance between D+ and D– to 1000pF or less. This

capacitance includes any cable capacitance between the remote temperature sensor and the TMP461-EP

device.

5. If the connection between the remote temperature sensor and the TMP461-EP device is less than 8in

(20.32cm) 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 TMP461-EP device as possible. Leave the remote sensor

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

6. Thoroughly clean and remove all flux residue in and around the pins of the TMP461-EP device to avoid

temperature offset readings as a result of leakage paths between D+ and GND, or between D+ and V+.

V+

D+

D-

GND

Ground or V+ layer

on bottom and top,

if possible.

NOTE: Use a minimum of 5mil (0.127mm) traces with 5mil spacing.

Figure 9-5. Suggested PCB Layer Cross-Section

TMP461-EP

SNIS241 – SEPTEMBER 2025

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