Highly resistant to external noise! Coreless current sensor "TLI4971/TLE497* series"

Resistant to disturbance noise! Coreless current sensor "TLI4971"

What is a coreless current sensor?

A current sensor is a sensor that detects the current flowing in the current path on a circuit board or the current flowing in a bus bar. Because a magnetic field is generated around the path through which the current flows, a magnetic sensor inside the current sensor detects the magnetic field and feeds back a signal proportional to the amount of current based on the magnetic information. Among current sensors that use this magnetism, those that do not use a magnetic core are called coreless current sensors.

Comparison of current detection methods

There are three methods for detecting current:

Shunt resistor method
This method involves placing a shunt resistor in the path being measured and detecting the amount of current by reading the voltage across the shunt resistor.

Electromagnetic core type
This method uses a magnetic core to collect the magnetic force generated around the path being measured, and then uses a magnetic sensor inside the current sensor to detect the amount of current.

Electromagnetic coreless method
This method does not use a magnetic core; instead, the current flowing through the current paths or bus bars on the board is drawn into the IC, and the amount of current is detected by a magnetic sensor inside the current sensor.

Features of each method

method	merit	Demerit
Magnetic Coreless	・Small size (no magnetic core required) ・Low heat generation -Simplification of insulation design ・Current detection possible on both bus bars and boards	・Mechanism design is complex ・Price for the product alone
With magnetic core	・Low heat generation -Simplification of insulation design	-Size and volume - Consideration of the characteristics of the magnetic core itself ・Only busbar current detection is possible
Shunt Resistor	・Abundant market track record	・Heat prevention (Since current flows through the shunt resistor, it is important to have a thermal design that takes heat generation into consideration.) ・Busbar current cannot be detected ・Signal transmission requires an isolation device

TLI4971/TLE497* Series Lineup

Infineon offers coreless current sensors for the following consumer, industrial and automotive applications:

The lineup is broadly divided into iCR type (TLI4971, TLE4971, TLE4973) and eCR type (TLE4972, TLE4973).
In the iCR type, the sensor element and current path are integrated and the structure for current detection is optimized inside the package, making it compact. However, in the eCR type, the sensor element and current path are independent, so verification of the structure for current detection, including the mechanical design, is required.

For details on each lineup and device selection, please download the documents below and contact us if you have any questions.

[Understandable even for beginners] Features of coreless current sensors and key points for implementation

table of contents:

1. Overview of coreless current sensors
2. Advantages of coreless current sensors
3. Current sensor implementation and support
4. Product lineup

Download materials here

Below we will introduce the TLI4971 series, which is relatively easy to implement for consumer and industrial applications.

TLI4971: 3.3V powered coreless current sensor

Product features

Selectable current sensing ranges: ±25A, ±50A, ±75A, ±120A
3.3V operation
analog output
High bandwidth for high speed measurement: typ.240kHz
Two built-in Hall elements for robust differential measurement
High-speed, dual-system overcurrent detection function
High accuracy current sensing independent of age and temperature (with built-in temperature and stress sensors)
Various parameters can be set using the built-in EEPROM

Block diagram / Package

Target application

Electric device (maximum 690Vms)
Solar Power Inverter
General-purpose and GaN-based inverters
charger
Power Supply

Sensing Method

The TLI4971 series has two Hall elements built into the package, and these Hall elements are used to measure current values differentially.

As shown in the diagram on the side, in contrast to the two Hall elements inside the package (black arrows), this product is a type that detects current by passing it inside the package, with current flowing internally as shown in the diagram (red arrows).

Because the current curves internally, a magnetic flux in the opposite direction is generated (green arrow), and this magnetic flux is sensed by each Hall element. Although it is necessary to insert a slit in the current path to be measured as shown in the diagram, this is a product that can be easily considered.

Differential measurement of current values

This product is resistant to external noise because it performs differential measurements, which may eliminate the need for shielding to remove external noise.

1) Magnetic fluxes V1 and V2 (red arrows) are detected from the current in the current path being measured.
② As the output is V1 and V2, the directions are opposite, so the main magnetic flux output is obtained differentially.
③ V3 and V4 (blue arrows) are generated as magnetic flux from the current path, which is an external noise source.
④ Since V3 and V4 have the same direction, noise can be eliminated when performing differential calculations.

Overcurrent Detection Mechanism

As mentioned above, this product has a built-in overcurrent detection mechanism that detects and flags overcurrent faster than normal current measurement output. There are two independent overcurrent detection mechanisms internally, and the overcurrent threshold can be set by the user by programming the EEPROM.

This function allows the overcurrent detection mechanism that is usually implemented in external circuits to be incorporated into the sensor IC, helping to reduce the number of components and secure mounting area.

Product Line

The TLI4971 series has a lineup divided by current detection range.

Among the products in each detection range, there are some that have passed the additional UL1577 dielectric strength test, and we also offer products that can be considered if you have strict requirements regarding dielectric strength voltage.