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What are the advantages of GESD series?

①Ultra low capacitance(0.05~0.10pF), higher cut-off frequency(7G);

②Max. operating temperature is 125℃, the same as ceramic component;

③Reliability is better(Organic is easy to age for using in the long term).

④Price is cheap. The minimum size can do 0603.

There are there Varistor series( SDV, SDVL, VPR), what’s the different between them?

SDV Series Varistor with multilayer chip structure, small size(0603~2012), can be used for ESD protection in DC power line or signal line, such as portable devices, etc. SDVL Series Varistor with multilayer chip structure, largger size, providing better capable of absorbing large energy: SDVL3216~10080SD series usually be used in high voltage DC power line, such as security system, automotive electronics, industrial instrument, etc. SDVL8063/10080KA series can be used in 110V/220V AC power to protect from lightning and it can replace part of leaded series in the area of height limited (such as low profile LED lighting, ultra-thin adapter and so on). VPR Series varistor with leaded structure, providing high working voltage, can be used in high voltage AC/DC circuit, such as various consumer electronics, domestic appliances etc.

Q: There are there Varistor series( SDV, SDVL, VPS), what’s the different between them?

SDV Series Varistor with multilayer chip structure, small size(0603~2012), can be used for ESD protection in DC power line or signal line, such as portable devices, etc.

SDVL Series Varistor with multilayer chip structure, largger size(3216~5650), providing better capable of absorbing large energy, therefore, usually be used in high voltage DC power line, such as security system, automotive electronics, industrial instrument, etc.
VPS Series varistor with leaded structure, providing high working voltage, can be used in high voltage AC/DC circuit, such as various consumer electronics, domestic appliances etc.

What is the major electrical characteristic and the application of polymer varistor (PESD) ?

Comparing with ZnO material varistor, polymer varistor provides an ultra low capacitance (0.1pF or lower) due to polymer material. But the trigger voltage is higher than that of ZnO varistor. Because of the ultra low capacitance, polymer varistors are widely used in high speed lines and interfaces for ESD prefecture such as HDMI IF, USB3.0 IF, etc.

When applying the varistor to a gigabit ethernet interface, we should choose varistor with low capacitance, however, low capacitance varistor can not withstand large energy pulse usually generated by

It is recommended to design two level protection system. A gas discharge tube can be placed on the first side of the network transformer in order to absorb large transient energy and varistors with small capacitance can be placed on the second side near the network IC in order to protect network IC.

What is the difference between varistor for pulse voltage suppression and ESD suppression? How do we choose a varistor for pulse voltage suppression?

Pulse voltage usually lasts for several mS, which results in large pulse energy. Varistor for pulse voltage suppression

should be capable of absorbing large energy therefore it is usually larger in size (3225~10080).
 
In order to make a suitable use of Varistor for pulse voltage suppression, the following should be noticed:

1. The max. working voltage of the varistor(VWDC) must exceed system rated voltage.
2. Rated single pulse transient (10/1000uS energy and 8/20uS peak current) of the varistor imply the ability to suppress surge current. Generally, larger size part can stand up to larger pulse energy, thus we should choose a varistor of appropriate size based on different situations.
3. Clamp voltage (Vc) is the peak voltage across the suppressor when measured under conditions of specified pulse current and specified waveform (8/20 or ESD pulse). Vc must be much lower than the maximal voltage that the protected system can withstand.
 

 

I find the test frequency for Sunlord varistor’s capacitance 1MHz, and some other companies 1kHz. Are the values of capacitance measured under both frequencies the same?

The capacitance tested at 1kHz is about 1.3 times of the one tested at 1MHz. Please notice test frequency of capacitance when choosing varistor part number.

I want to protect ESD of USB2.0 interface. What is the suitable capacitance of varistor?

The capacitance of a varistor will affect signal‘s time delay and could cause signal distortion. And low capacitance is suitable for high frequency signal. Please refer the following recommended capacitance for different circuits.

Protected Device
Data Rate & Frequency
Rise time
Capacitance
HDMI/USB3.0
4.80Gbps/10.2Gbps
<0.5nS
<1pF
USB 2.0/IEEE1394
400~480Mbps
0.5~0.6nS
≤3pF
RS232、IrDA1.0
115.2 Kbps
1uS~8uS
10~200pF
Audio
20~20000Hz
0.05mS~50mS
10~360pF

What does the code “A/E/H/S” of varistor’s part number mean? How to select a varistor?

Sunlord provides four types of varistors, SDV-A types, SDV-E types, SDV-H types and SDV-S types.

SDV-A Type: Somewhat large capacitance (>100pF) and high peak pulse power for over-voltage protection and ESD countermeasure use.
SDV-E Type: Low capacitance (10~100pF) for general ESD countermeasure use.
SDV-H Type: Very low capacitance (<10pF) for high speed signals ESD countermeasure use.
SDV-S Type: Low capacitance and low DC working voltage for high speed signals ESD countermeasure use.
 
When selecting varistors, please pay attention to the following four aspects,
(1)   VDC: Max DC Voltage of Varistor (> maximum signal DC voltage)
(2)   Capacitance: Suitable for signal frequency. Low capacitance is suitable for high frequency signal.
(3)   Layout: Close to ESD source
(4)   Ground Design: Good ground