IN+

IN±

Hall

Element

Bias

Temperature

Compensation

----------------------

Offset Cancellation

VREF

VOUT

Precision

Amplifier

Output

Amplifier

VS

GND

Reference

Sampling

11

TMCS1100

www.ti.com

SBOS820 – SEPTEMBER 2019

Product Folder Links: TMCS1100

Submit Documentation Feedback

Copyright © 2019, Texas Instruments Incorporated

9 Detailed Description

9.1 Overview

The TMCS1100 is a Hall-sensor-based precision current sensor, featuring a 600-V basic isolation working

voltage, < 1% full-scale error across temperature, and an external reference voltage enabling unidirectional or

bidirectional current sensing. Input current flows through a conductor between the isolated input current pins. The

conductor has a 1.8-mΩ resistance at room temperature for low power dissipation and a 20-A RMS continuous

current handling capability up to 125°C ambient temperature on the TMCS1100EVM. The magnetic field

generated by the input current is sensed by a Hall sensor and amplified by a precision signal chain. The device

can be used for both ac and dc current measurements and has a bandwidth of 80 kHz. There are four fixed-

sensitivity device variants for a wide option of linear sensing ranges, and the TMCS1100 can operate with a low

voltage supply from 3 V to 5.5 V. The TMCS1100 is optimized for high accuracy and temperature stability, with

both offset and sensitivity compensated across the entire operating temperature range.

9.2 Functional Block Diagram

9.3 Feature Description

9.3.1 Current Input

Input current to the TMCS1100 passes through the isolated side of the package leadframe through the IN+ and

IN– pins. The current flow through the package generates a magnetic field that is proportional to the input

current, and measured by a galvanically isolated, precision, Hall sensor IC. The low-ohmic leadframe path

reduces power dissipation compared to alternative current measurement methodologies, and does not require

any passive external components on the high-voltage side. In addition, no isolated supplies or control signals are

needed on the high-voltage side, further simplifying implementation. As a result of the electrostatic shielding on

the Hall sensor die, only the magnetic field generated by the input current is measured, thus limiting input voltage

switching pass-through to the circuitry. This configuration allows for direct measurement of currents with high-

voltage transients without signal distortion on the current-sensor output.

The current input leadframe conductor has a nominal resistance of 1.8 mΩ at 25°C. The leadframe is composed

of copper; therefore, the leadframe has a positive temperature coefficient that causes resistance to increase at

higher temperatures. A typical temperature coefficient is 3300 ppm/°C, causing a 33% rise in resistivity for every

100°C of leadframe temperature change from room temperature.