ISOTMP35RDFPR datasheet(17/44 Pages) TI2

17 / 44 page

The high CMTI performance is enabled by the internal isolation structure and low parasitic coupling across the

barrier. In addition, system-level filtering and proper PCB layout further reduce the impact of high-frequency

transients (see Section 8.1.5.1 for more details on filtering techniques).

7.3.3 Thermal Response

The SSOP-12 package is designed to maximize the heat flow and minimize the thermal response time from the

TSENSE pins to the temperature sensor, while also providing the 5kVRMS isolation rating (UL 1577).

The thermal response of the ISOTMP35R depends on the thermal coupling between the TSENSE pins and the

heat source, as well as the surrounding environment and PCB design. Unlike conventional temperature sensors

that measure ambient or board temperature, the ISOTMP35R is designed to measure the temperature of a

localized heat source through direct thermal coupling. This is achieved through dedicated TSENSE pins that are

intended to be placed in close proximity to the heat-generating element.

Because thermal behavior varies significantly across applications, the ISOTMP35R is characterized under

multiple test conditions to provide a comprehensive understanding of device performance. These conditions

include directional heating, stirred liquid environments, and still air environments, which are discussed in the

following sections.

7.3.3.1 Stirred Liquid Thermal Response

Stirred liquid thermal response represents a best-case thermal condition for uniform temperature coupling across

the package, in which the entire device is exposed to a controlled and homogeneous temperature environment.

In this test, the device is immersed in a circulated fluid bath so that all parts of the package experience the

same temperature simultaneously. This minimizes thermal gradients across the device and reflects the intrinsic

response of the internal temperature sensor.

Figure 7-5 illustrates the stirred-liquid test configuration, and Figure 7-6 shows the corresponding measured

thermal response for a temperature step of 125°C (25°C to 150°C). The red solid reference line in Figure 7-6

indicates the final steady-state temperature (100%), while the response curve shows the transient behavior of

the device approaching this value.

ISOTMP35R

T = T

A = 25°C

Outside of bath

Figure 7-5. Stirred Liquid Test Setup

Time (s)

-2

100

125

T63%  2.0s

T86%  6.0s

VOUT

Figure 7-6. Thermal Response (Stirred Liquid Bath)

Under these conditions, the device exhibits a first-order thermal response. The output reaches approximately

63% of the final value in about 2.0s and approximately 86% in about 6.0s, consistent with first-order system

behavior.

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ISOTMP35R

SNIS244A – SEPTEMBER 2025 – REVISED MAY 2026

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