2.2 High Voltage Connection Setup Guide
2.2.1 Detaching the Sensor
The ISOTMP35BEVM functions with or without the sensor breakout board. However, to evaluate the ISOTMP35
in high voltage high temperature applications, the sensor breakout board must be detached to disconnect the
breakout sensor board. To detach the sensor board and reconnect correctly, follow these recommendations:
• De-solder bridge connectors from pads on both side.
• Break off the sensor board from the controller board along the perforations.
• Reconnect sensor board and controller board with wires soldered to labeled pads. The signals traveling
across these wires are low voltage, however the wires themselves must be rated to handle high-voltage
levels.
Depending on the application, the sensor board can be connected in such a way that the wires
connecting the EVM cross over other high voltage signals or components. If low voltage rated wires
are used in that case, then the wires and EVM can be damaged if the wires and EVM come into
physical contact with a high voltage signal.
The user can also choose the voltage on the sensor breakout board 3.3 V & GND pads. The ISOTMP35 can
accept any supply voltage from 2.3 V to 5.5 V.
2.2.2 Attaching Sensor Section to High Voltage Heat Source
Once the user has reconnected the sensor breakout board, the user can attach the EVM to a high-voltage heat
source using the bottom-side copper plate. This plate can be attached directly to a heat source, such as a
heat-sink from a high-power MOSFET or a high-voltage bus bar, using glue or screws.
• For best thermal conductivity, do not place an insulator between the high-voltage heat source and the EVM
bottom copper plate. Direct metal-to-metal contact is recommended.
• To decrease the ISOTMP35 response time, apply a thin layer of thermal conductive paste between the
connector and the high-voltage heat source.
• Dissimilar metals in contact can increase the thermal resistance, to minimize this effect use thermal
conductive paste.
• If screwing the EVM bottom copper connector on a high-power MOSFET, then TI recommends to minimize
connection distance to the MOSFET.
• When screwing on the EVM to any high-voltage heat source, note that the FR4 expands and contracts with
temperature. FR4 is a forgiving dielectric in terms of thermal expansion, but the user must periodically check
that the screwing remains fastened when safe to do so.
• When gluing the EVM copper pad to a high voltage heat source, use as little glue as possible to make sure
the connection is secure, excess glue increases the thermal resistance, therefore increasing response time.
Once again, thermal conductive paste between the two different metals helps to reduce the metal-to-metal
thermal resistance.
2.3 Perforations
There are perforations between the USB controller and the ISOTMP35 sensor, these exist so that after the
bridge connectors between the pads are desoldered, the two sides of the EVM can be broken apart easily.
2.4 Status LEDs & Subregulator
The ISOTMP35BEVM includes LEDs to indicate the board status; the green LED D3 illuminates when voltage
is supplied to the 3.3V net. The 3.3V net is connected directly to pin 1 of the ISOTMP35. U1 is the onboard
regulator which supplied the 3.3V net, and is enabled and disabled by switch S1. For normal operation of the
EVM, S1 must be enabled. When S1 is disabled, the green LED D3 turns off.
The red LED D4 is the MSP430F5528 status LED. Table 2-1 shows what the different modes of operation mean.
www.ti.com Hardware
SBOU312 – AUGUST 2023
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ISOTMP35 Evaluation Module 5
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