SMD capacitors used most in ESLs

2025-01-13

Electronic shelf labels is more and more popular in our lifetime. You can find ESLs in Retail Industry like Supermarkets and Hypermarkets, Convenience Stores, Pharmacies, Warehousing and Logistics , Office and Conference Rooms, Hospitality Industry, Medical and Health Care,Manufacturing Industry in their production Lines.

Here are talk about Electronic shelf labels typically work principles.

Radio Frequency Identification (RFID) Technology:

ESLs often use passive RFID. The system consists of a reader and the labels. The reader emits a radio frequency signal. When the signal reaches the ESL, the antenna in the label captures the electromagnetic energy. This energy is used to power the integrated circuit (IC) in the label.

The IC contains a unique identification number and product information such as price, product name, and barcode data. The IC modulates the reflected signal back to the reader according to the stored information. The reader then decodes this signal to obtain the relevant product details.

E Ink or Other Display Technologies:

The information received from the IC is used to drive a display. For example, e ink displays are commonly used. E ink is a bistable display material, which means it can hold the displayed image without continuous power. When the IC sends a signal to update the display, the appropriate electric fields are applied to the e ink capsules to change the color and show the new information such as a new price or product details.

Let’s look at the Circuit Characteristics of Electronic Shelf Labels.

Low Power Consumption:

The circuit design of ESLs emphasizes low power operation. Since many ESLs use passive RFID, they rely on the energy harvested from the reader's radio frequency signal. The IC and other components are designed to consume as little power as possible during standby and data transmission. For example, the power management circuitry in the label ensures that only the necessary components are active during different operating modes, such as when receiving a signal from the reader or updating the display.

Simple Antenna Circuit:

The antenna circuit is a crucial part. It is usually designed to have a resonant frequency that matches the operating frequency of the RFID system, often in the high frequency (HF) or ultra high frequency (UHF) range. The antenna's impedance is carefully matched to the input impedance of the IC to ensure efficient power transfer and signal reception/transmission. The circuit may include components like matching capacitors to optimize the antenna's performance.

Display Driver Circuit:

For ESLs with displays, there is a display driver circuit. In the case of e ink displays, this circuit provides the necessary voltage waveforms and control signals to update the display. The driver circuit needs to be able to handle the specific requirements of the display technology, such as the voltage levels and timings needed to change the state of the e ink capsules. It is also designed to minimize power consumption during display updates and to ensure the stability and accuracy of the displayed information.

In ESLs (Electronic Shelf Labels), the commonly used MLCCs (Multilayer Ceramic Capacitors) mainly include the following types:

X5R and X7R MLCCs

Stable capacitance: X5R and X7R dielectric materials have relatively stable capacitance characteristics over a wide temperature range, which can ensure the stability of the ESL's circuit performance in different environmental temperatures.

Low ESL and ESR: They have the advantages of low equivalent series inductance (ESL) and low equivalent series resistance (ESR), which is very important for the high-frequency operation of ESLs. It can reduce signal attenuation and distortion, and improve the efficiency and speed of signal transmission.

NP0 MLCCs

High stability: NP0 is a temperature compensation type of dielectric material, and its capacitance change with temperature is extremely small, with high stability and reliability. It is very suitable for the circuit of ESLs that require high stability, such as the oscillator circuit and the filter circuit, which can ensure the accurate operation of the circuit.

Low loss: NP0 MLCCs have low dielectric loss at high frequencies, which can reduce energy loss and heat generation in the circuit, improve the efficiency of the circuit, and are beneficial to the long-term stable operation of ESLs.

Ultra-small and low-profile MLCCs

Space-saving: ESLs usually have limited space, and the use of ultra-small and low-profile MLCCs can save space on the circuit board and make the design of ESLs more compact. For example, 0201, 0402 and other small-size MLCCs are often used in ESLs.

Lightweight: The lightweight characteristics of MLCCs are also very important for some portable or handheld ESL devices, which can reduce the overall weight of the device and improve its portability.

Hongda Capacitors offer a wide range of MLCC, case size :0210-2220, capacitance range 0.1pF~470uF, voltage range: 2.5V-7200V.

In ESLs (Electronic Shelf Labels), the commonly used SMD tantalum capacitors mainly include the following series:

AVX TAJ Series

General Purpose and Common Values: The AVX TAJ series is a general-purpose molded tantalum chip capacitor and is produced in some of the most common values and sizes. It can meet the basic requirements of capacitance and voltage in ESL circuits.

Reliability: AVX is a well-known brand with high-quality products and reliable performance. The TAJ series capacitors have stable capacitance characteristics, small capacity error, and can ensure the stability of the ESL circuit.

Kemet T491 Series

Good Electrical Properties: The T491 series capacitors of Kemet have the characteristics of low equivalent series resistance (ESR) and good high-frequency performance, which can effectively filter out high-frequency noise in the ESL circuit and improve the signal quality.

Wide Temperature Range: It can operate normally in a wide temperature range, and is suitable for the working environment of ESLs which may face different temperatures.

Vishay 293D Series

Industry Standard: The 293D series of Vishay is a common series of tantalum capacitors, and its electrical performance and size specifications meet the general requirements of the industry. It is easy to purchase and replace, and is convenient for the production and maintenance of ESLs.

Stable Performance: With stable capacitance and leakage current, it can ensure the long-term stable operation of the ESL circuit.

Hongda Capacitors CA45 series can perfectly replace AVX TAJ series, Kemet T491 Series, Vishay 239D series. Here is our cross table for reference.

Welcome to share your project RFQ to emily@hongdacap.com.hk  to get best offer.