High-frequency noise solution! Further expansion of the lineup of "YFF Series" 3-terminal feed-through filters for automotive use

TDK has recently expanded its lineup of 3-terminal feedthrough filters, known as the "YFF Series."
With advancements in automotive electronic systems aimed at enhancing safety, comfort, and infotainment capabilities, there is an increasing demand for measures to prevent system malfunctions.
To suppress voltage variation and high-frequency noise, which can cause such malfunctions, numerous capacitors are typically employed. However, the trend toward miniaturization of these systems raises concerns about mounting space limitations due to the increased number of components.
To address these challenges, 3-terminal feedthrough filters, characterized by low ESL (Equivalent Series Inductance), are gaining significant demand. Their high noise suppression effectiveness is expected to reduce the number of components and improve performance characteristics.

ECU Trends

Features of the Two Expanded Products

Solution Example ①: YFF15AC1V224M / YFF21AC1A475M

Solution Example ②: YFF15AC1V224M

Summary

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ECU Trends

With the miniaturization and increased functionality of automotive electronic systems, the number of electronic components installed and their usage under harsher environments are increasing. Therefore, electronic components must meet the following three requirements:

・Suppression of voltage variation
・Reduction of high-frequency noise
・Reduction in the number of mounted components

Features of the Two Expanded Products

・YFF15AC1V224MT0Y0N
Despite its compact 1005 size, this product features a rated voltage of 35V,
making it suitable for a wide range of power lines, from input to output in power supply systems.

Figure 2: Introduction of YFF15AC1V224M (Characteristics and Insertion Loss)

・YFF21AC1A475MT0Y0N
This product achieves a high capacitance of 4.7µF while maintaining a rated voltage of 10V.
For example, as an input capacitor for a 5V line,
it effectively reduces voltage variations while also addressing high-frequency noise.

Figure 3: Introduction of YFF21AC1A475M (Characteristics and Insertion Loss)

The assumed circuit blocks are as follows.
This product is suitable for a wide range of power lines from input to output in power supply systems.

Product Name	Application	Form	Capacitance	RV	Current
YFF15AC1V224M	Primary Side Secondary Side Filter / Decoupling	1.0×0.5×0.4mm	220nF	35V	2A
YFF21AC1A475M	Primary Side Secondary Side Smoothing / Filter / Decoupling	2.0×1.25×0.85mm	4.7uF	10V	4A

Table 1: Specifications

Solution Example ①: YFF15AC1V224M / YFF21AC1A475M

When using only 2-terminal capacitors, the voltage variation exceeded the IC's recommended maximum voltage. By using the new 3-terminal feedthrough filters with the same capacitance and size, the voltage variation was suppressed by 39%, bringing it within the recommended maximum voltage range.
In this example, to achieve a similar level of voltage variation suppression using only 2-terminal capacitors, the number of 2-terminal capacitors would need to be doubled.
Thus, the 3-terminal feedthrough filters demonstrate excellent noise suppression effectiveness with fewer components.

Configuration	i	ii	iii
YFF15AC1V224M (3-terminal/1005/35V/220nF/2A) Shunt-thru	ー	○ 2pcs	ー
YFF21AC1A475M (3-terminal/2012/10V/4.7uF/4A) Shunt-thru	ー	○ 2pcs	ー
2-terminal/2012/10V/4.7uF	○ 2pcs	ー	ー
2-terminal/1005/35V/220nF	○ 2pcs	ー	○ 2pcs
2-terminal/1608/35V/1uF	ー	ー	○ 2pcs
2-terminal/1608/10V/2.2uF	ー	ー	○ 4pcs

Table 2: Evaluation Configuration

■Evaluation Conditions: Switching Frequency: 4MHz, Input Voltage: 5V, Output Voltage: 2.5V, Output Current: 4.5A

When only 2-terminal capacitors were connected, the voltage variation exceeded the IC's recommended maximum voltage. However, by using 3-terminal feedthrough filters with the same capacitance and size, the voltage variation was suppressed.
Additionally, to achieve a similar level of voltage variation suppression as 3-terminal feedthrough filters, the number of 2-terminal capacitors must be increased.
In this example, increasing the number of 2-terminal capacitors from 4 to 8 resulted in voltage variation comparable to that of the 3-terminal feedthrough filters.

Solution Example ②: YFF15AC1V224M

The YFF15AC1V224M, with its compact 1005 size, is ideal for noise suppression in small applications with high mounting density.
The following example describes its application to NFC power lines, represented by keyless entry systems.

Configuration	i	ii
YFF15AC1V224M (3-terminal/1005/35V/220nF/2A) Feed-thru	ー	○
2-terminal/1608/6.3V/10uF	○	○
2-terminal/1005/50V/100nF	○	○

Table 3: Evaluation Configuration

The use of a 3-terminal feedthrough filter is expected to reduce noise in the power supply line.
This filter effectively suppresses high-frequency noise in the power supply line, ensuring stable operation of various devices.

Summary

This solution guide has introduced the high noise suppression effectiveness of the two expanded products in the YFF Series.
The key features of each product are summarized as follows:

・The YFF15AC1V224MT0Y0N, despite its compact 1005 size, features a rated voltage of 35V, making it suitable for a wide range of power lines, from input to output in power supply systems.
・The YFF21AC1A475MT0Y0N, with its high capacitance and rated voltage of 10V, simultaneously reduces voltage variation and suppresses high-frequency noise.

In addition to the products introduced here, TDK offers a wide lineup of products with various rated voltages and capacitances, enabling comprehensive product proposals from the input to the output side of power supplies.
Please feel free to contact TDK if you require support or have interest in using our products.