To mitigate these effects, an RC filter consisting of RFILTER and CFILTER is recommended at the ADC input. This

filter attenuates high-frequency noise, isolates the sensor output from ADC sampling transients, and improves

signal stability during conversion.

Figure 8-2 shows a recommended connection of the ISOTMP35R output to an ADC. In this configuration, CLOAD

provides local high-frequency filtering at the device output, while the RC network at the ADC input further

reduces noise and transient effects.

GND

+

–

3.1V to 34V

100nF

GND

GND

GND

CFILTER

RFILTER

CLOAD

ADC

GND

RISO

Keep space beneath

device free of any planes,

traces, pads and vias

VDD

VOUT

GND

NC

NC

NC

ISOTMP35R

1

2

3

4

5

6

7

8

9

10

11

12

Heat

High Voltage Heat Source

Figure 8-2. Connecting the ISOTMP35R Output to an ADC

In systems with long trace lengths or high levels of electromagnetic interference, additional filtering or buffering is

often required to maintain measurement accuracy.

8.1.4 Power Supply Recommendations

The ISOTMP35R operates from a supply voltage range of 3.1V to 34V, enabling flexible integration into a wide

range of system architectures.

A stable and low-noise supply is recommended to achieve high measurement accuracy. A 0.1µF bypass

capacitor must be placed as close as possible to the VDD pin. This capacitor provides a low-impedance path for

high-frequency transients and is required for proper device operation.

In many applications, the supply voltage is derived from a switching regulator or is exposed to high-frequency

noise. In these cases, additional filtering is required to reduce noise from coupling into the device.

A ferrite bead placed in series with VDD, in combination with a local bypass capacitor, can be used to attenuate

conducted high-frequency noise. Select ferrite beads with low DC resistance (DCR < 1Ω) to avoid introducing

voltage drops that affect device performance.

The effectiveness of supply filtering depends on the system noise environment and PCB layout. Additional

filtering techniques are described in Section 8.1.5.1.

8.1.5 EMI Mitigation and Filtering

The ISOTMP35R is commonly used in high-voltage systems that include fast-switching devices such as

MOSFETs, IGBTs, or switching regulators. These systems generate high dv/dt transients and electromagnetic

interference (EMI), which can couple into the sensor output through PCB traces, parasitic capacitances, or the

isolation barrier.

If not properly mitigated, this coupled noise can introduce voltage disturbances at the output (VOUT), resulting in

measurement error or reduced system accuracy.

The ISOTMP35R provides high common-mode transient immunity (CMTI), which minimizes the impact of fast

common-mode voltage transitions, as described in Section 7.3.2.3. However, system-level filtering and layout

practices are required to further reduce noise coupling and maintain reliable operation.

Effective EMI mitigation is achieved through a combination of local output filtering, signal-path filtering, supply

filtering, and careful layout practices.

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ISOTMP35R

SNIS244A – SEPTEMBER 2025 – REVISED MAY 2026

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