ISOTMP35RDFPR datasheet(24/44 Pages) TI2

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8.1.2 Output Buffering and Signal Integrity Considerations

In many applications, the ISOTMP35R output can be connected directly to an ADC input without requiring an

external buffer. The output stage provides sufficient drive capability for typical capacitive loads and short PCB

interconnects.

As described in Section 7.3.2.2, the output remains stable for capacitive loads up to 2.2nF without additional

components. For larger capacitive loads, the use of a series isolation resistor (RISO) enables stable operation

independent of load capacitance. In these cases, an external buffer is not required for stability.

In certain system conditions, an external buffer can improve overall signal integrity and robustness. These

conditions are typically related to long PCB traces, cable interfaces, multiple loads, or electrically noisy

environments where signal attenuation and coupling can degrade performance.

An external buffer can be implemented as either a single-ended or differential stage, depending on

system requirements. Single-ended buffers are typically sufficient for moderate trace lengths and low-noise

environments. Differential signaling can be used in applications requiring improved noise immunity or reliable

transmission over longer distances.

In addition, buffering can help isolate the sensor output from downstream circuitry, reducing the impact of

distributed parasitics and improving performance in high-EMI environments.

Figure 8-1 shows an example implementation in which the ISOTMP35R output is buffered and transmitted as a

differential signal for improved noise immunity over longer distances.

THP210

ISOTMP35R

OUT

GND

ISO

LOAD

Figure 8-1. Buffered Differential Pair Data Transmission

In applications with short trace lengths, a single load, and limited noise coupling, the ISOTMP35R output can be

used directly without a buffer.

8.1.3 ADC Interface Considerations

The ISOTMP35R provides an analog output voltage that is intended for direct interfacing to an analog-to-digital

converter (ADC).

To achieve the specified temperature accuracy, a minimum ADC resolution of 12 bits is recommended. For

example, with a 2.5V reference, a 12-bit ADC provides an LSB size of approximately 0.61mV, corresponding to

a temperature resolution of approximately 0.061°C per LSB. This resolution is sufficient for most temperature

monitoring applications.

Higher-resolution ADCs (for example, 14-bit or 16-bit) can be used in systems requiring improved resolution.

However, overall system accuracy is typically limited by other factors such as noise, thermal gradients, and PCB

layout, and does not significantly improve with higher resolution alone.

The ADC input presents both capacitive loading and dynamic sampling currents. These effects can introduce

voltage disturbances at the sensor output, including transient droop and high-frequency noise. As described in

Section 7.3.2.2, capacitive loading also influences output stability and must be considered in the system design.

ISOTMP35R

SNIS244A – SEPTEMBER 2025 – REVISED MAY 2026

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