Newsletter-Spring 2022 | High-End MELF SMD Resistors Manufacturer - FIRSTOHM

It has been more than two years since pandemic COVID-19 outbreak. Recently, the shocking war between Ukraine and Russia happened. Both Russia and Ukraine have rich minerals resources and play inevitable roles in global supply chain for these minerals. The outbreak of war between the two countries have definitely worsened the impact to the supply chain for electronic industry. How to prevent supply chain of all raw materials from shortage and to deliver customers' orders on schedule have repeatedly tested the survival of enterprises. FIRSTOHM is one of the few companies who is able to design thin-film resistors according to customer's requirements with high quality and reliability. We’re specialized in MELF resistors since 1969, ISO9001/14001 certificated manufacturer.

qrc@firstohm.com.tw

On Duty: 9am - 6pm

Newsletter-Spring 2022

FIRSTOHM Newsletter - Spring 2022

FIRSTOHM Newsletter - Spring 2022

Newsletter-Spring 2022

It has been more than two years since pandemic COVID-19 outbreak. Recently, the shocking war between Ukraine and Russia happened. Both Russia and Ukraine have rich minerals resources and play inevitable roles in global supply chain for these minerals. The outbreak of war between the two countries have definitely worsened the impact to the supply chain for electronic industry. How to prevent supply chain of all raw materials from shortage and to deliver customers' orders on schedule have repeatedly tested the survival of enterprises.


01 Mar, 2022 FIRSTOHM
e-commerce platforms
e-commerce platforms

★FIRSTOHM e-commerce

The flow of online transactions are getting hot due to the epidemic, FIRSTOHM’s products can also be purchased through the e-commerce platform, and FIRSTOHM wish to service more customers by way of online sales. The URL are as follows:
Allchips, https://www.allchips.com
ICDEAL, https://www.icdeal.com
Sekorm, https://www.sekorm.com
Hqchip, https://www.hqchip.com
SZLCSC, https://www.szlcsc.com

★ Carbon or ceramic composition resistors

Alternative Parts
If you consider the in-circuit performance attainable by using carbon or ceramic composition resistors that could handle high surges, peak power or energy - example applications included power charging/ discharging, inrush current limiting, RC Snubbers, High Voltage Power Supplies, etc.
The Firstohm SSR Series is currently offered with the lead-time of only 8~10 weeks - while the unit price is significantly more cost-effective compared to carbon or ceramic composition resistors. Ex : The Ohmite OX/OY Series is available in two power ratings:
• OX Series - 1W Ceramic Composition Resistor
• OY Series - 2W Ceramic Composition Resistor
The SSR resistor is available from 1W~3W @70DegC, 400V and with a Max Permissible Surge Voltage of 25KV and can be considered as a replacement to the OHMITE OX/OY Series.

★ Application of Pre-Charge Resistor

Before the core device of the electric vehicle is powered on, the voltage at both ends is zero, which is equivalent to a short circuit at the moment of power-on, resulting in a large charging current, which can easily cause damage to the power device. Therefore, it is necessary to connect a pre-charge resistor in series in the charging circuit during the pre-charge process to limit the amount of the pre-charge current.
From market, the commonly used pre-charge resistors included Aluminum Housed Power Resistors, Cement Resistors and High-Power Through Hole Wirewound Resistors, etc.
FIRSTOHM SWM series are SMD Wirewound Resistor, it possesses advantages such as smaller size, SMD type and multi-national patents with a high reliability in anti-surge characteristics, which are very suitable for pre-charge applications.
Refer to below case study, the capacitance value is 100 mF. If input voltage is supplied 60V, pre-charge resistance is 22 ohm, the voltage changing time is 1.1 second, the maximum power reach 163.64W, therefore, when high voltage source connect to capacitor, it is requested to limit surge current, in order to avoid electric impact to the other components.

※Test Result : Passed !

a.) Test Conditions:
Ambient temperature : 25℃
Pre-Charging RES. : SWM200,22R,5% *4PCS
Input Voltage : 60VDC
Capacitor : 100 mF
Charge/Discharge : Charging time @5 Sec. / Discharging time@55 Sec.
Number of switching : 1,000
τ=RC/2= (22Ω*100mF) /2 =1.1 Sec.
E=1/2CV2 =1/2(100mF) (60V)2=180J

b.) Evaluated circuit

Evaluated circuit

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What's New At Firstohm-Spring 2022
What's New At Firstohm-Spring 2022

Pre-charge Resistor for Automotive

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High-End MELF SMD Resistors Manufacturer - FIRSTOHM

Located in Taiwan since 1969, First resistor & condenser Co. Ltd. is a MELF type resistor manufacturer. ISO9001/14001 certificated, award winning and patented design thin-film resistors, including anti-surge resistor, precision resistor, stability resistor, high voltage resistor, current sense resistor, automotive grade resistor, high power resistor, circuit protection resistor, fusible resistor and so forth.

FIRSTOHM's resistors are being widely used in industry applications, such as power supply, telecom, meter, medical, automotive and lighting. The strong R&D has allowed FIRSTOHM to develop new technology and obtain hundreds of patents, as well as develop specialty resistors, such as high voltage resistor, short circuit protection resistor, dual power resistor, high humidity resistor, etc.

FIRSTOHM has been offering customers high quality MELF resistors since 1969, both with advanced technology and 50 years of experience, FIRSTOHM ensures each customer's demands are met.