Keep space beneath

device free of any planes,

traces, pads and vias

VDD

VOUT

GND

NC

NC

NC

ISOTMP35R

1

2

4

5

6

7

8

9

10

11

12

Heat

High Voltage Heat Source

3

GND

GND

GND

ADC

+

–

3V to 34V

100nF

RFILTER

CFILTER

CLOAD

GND

GND

Figure 7-2. Connecting the ISOTMP35R Output to an ADC

7.1.3 Electromagnetic Noise Mitigation

The ISOTMP35R device is designed to connect to high-voltage heat sources, including switching MOSFETs.

These devices often generate electromagnetic interference (EMI) and noise that can couple into the

ISOTMP35R output (VOUT). If not properly filtered, this noise can cause large temperature accuracy errors.

Effective EMI mitigation is therefore critical to maximizing the accuracy and reliability of the ISOTMP35R device.

7.1.3.1 Filtering Techniques

EMI mitigation begins at the schematic level. TI recommends using RC filters or Pi filters on ISOTMP35R traces

to attenuate coupled noise. In addition, ferrite beads on VDD and GND help suppress high-frequency noise

before the noise couples into the device.

Place filtering components both at the ISOTMP35R pins and at the signal termination point. For example,

placing an RC filter only near the device leaves the rest of the trace vulnerable to noise pickup. Figure 7-3

illustrates an example filter configuration for reducing EMI effects.

Keep space beneath

device free of any planes,

traces, pads and vias

VDD

VOUT

GND

NC

NC

NC

ISOTMP35R

1

2

4

5

6

7

8

9

10

11

12

Heat

High Voltage Heat Source

3

GND

GND

GND

ADC

RFILTER 2

CFILTER 2

CLOAD

100nF

C2

C3

+

–

GND

3V to 34V

Ferrite Bead

(DCR < 1 )

Ferrite Bead

(DCR < 1 )

GND

RFILTER

CFILTER

Figure 7-3. Example Filtering for EMI Mitigation

7.1.3.2 General Design Guidelines

While filter design depends on system-level noise sources, the following practices are recommended:

• Place a 0.1µF bypass capacitor as close as possible to the ISOTMP35R VDD pin. This capacitor is required

for optimal operation and should always be present, even when additional filters are used.

• Use C0G/NP0 capacitors for signal-path filtering, and limit SMT package size to 0603 or smaller to minimize

parasitic effects.

ISOTMP35R

SNIS244 – SEPTEMBER 2025

www.ti.com

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