High performance resistors are key to meeting the demanding requirements of portable medical electronics designs
Medical electronics equipment is not longer just found in hospitals, clinics and doctors surgeries. Neither is its use restricted to qualified practitioners. Instead designs have become smaller, more portable and easier to use to the point where now appliances like defibrillators are deployed in many public places such as sports venues, schools, airports, health & fitness clubs and many commercial and government offices.
Click here for full article:
Riedon is targeting the demanding requirements of current sensing and shunt applications with its comprehensive portfolio of low ohmic value resistors, ranging from the economical bare metal element MSR series through to its CLSA series chip resistors that provide AEC-Q200 compliance for use in harsh automotive environments.
Utilizing various technologies, Riedon offers ±1% tolerance resistances from 0.5 milliohms up to 1 ohm in various package formats with TCRs as low as ±20ppm/oC and power ratings up to 5 Watts. For tolerances down to ±0.1%, Riedon is also able to supply four terminal versions of its axial lead low ohm power resistor.
The MSR series uses a bare metal element in an all-welded construction for through-hole circuit board mounting to provide resistance values from 5mΩ to 100mohm, while also achieving low inductance (<10nH) and low TCR (±20ppm/C). MSR resistors are available in 1W, 3W and 5W power ratings with tolerances of ±1% or ±5%. For surface-mount applications, the company offers several chip resistor solutions: its MNRS chip shunt resistors offer exceptional long-term stability and low inductance with 4W and 6W ratings and resistances from 1mohm to 4mohm; the CSR family of ultra low ohm metal strip chip resistors come in three sizes (1206 / 2010 / 2512) for power ratings from 1W to 3W, with standard and customized resistance values from 0.5mohm to 15mohm; and featuring an alumina substrate for high power dissipation the CLS/CLSA series of chip resistors operate over -55C to +155C, with the CLSA parts meeting the Automotive Engineering Council’s AEC-Q200 stress test qualification, says the company.
“Current sensing applications insert a low ohmic precision resistor in series with the load current, creating a small voltage drop that can be readily measured and used to calculate the current flowing through the resistor”, explains Phil Ebbert, Riedon’s VP of engineering, “Resistance values of just a few milliohms allow currents of several Amps, even tens of Amps, to be handled with device power ratings up to 5 Watts. Riedon’s capability to produce such low ohmic values, with well defined tolerances, enables it to serve a wide range of current sensing and shunt resistor applications.”
When comparing thin film and thick film resistors, thin film resistors are able to achieve much lower tolerances and resistor temperature coefficients, have lower noise, lower parasitic inductance, and lower capacitance. With these better qualities, thin film resistors have generally been much more expensive to produce than their thick film resistor cousins, however, improvements to mass production techniques and operation conditions have greatly reduced the cost to manufacture high-quality, precision thin film chip resistors. Riedon’s CAR series resistors are available with tolerances to ±0.01% and temperature coefficient ratings to ±25 ppm/°C at a fraction of the price of the typical thin film chip.
Here are some applications where these thin-film resistors make sense for use:
Instrumentation - Aircraft instruments, altimeters, gauges, flight control systems.
Medical - Heart monitors, diagnostic equipment, scales, scopes.
Audio - Radio receivers, DVD/Blu-Ray players, amplifiers, tuners, equalizers, crossovers.
Computer - Voltage regulators, voltage dividers, network communications, process controllers.
Power Suppliers - Step-Up or Step-Down converters, input or output voltage sets, voltage dividers.
Telecom - Voice communications, routers, bridges, multiplexes, fiber/wire converters.
HVAC – AC, ventilation, heating control.
RF – Wireless routers, Bluetooth modules, cell phone receivers, display drivers.
Electrostatic discharge (ESD): A high voltage pulse induced into a device as a result of its coming in contact with or in proximity to an electrically charged object. In very dry climates, charges build up on any moving object including people. These charges may pass (discharge) to an electronic device when the charged body comes into proximity with it.
A device is said to be ESD-sensitive if this passage of charge does harm to the device in any way. In the resistor-world, generally, ESD sensitivity is related to the function of the resistor's size. The smaller the resistor, the less space there is to spread the energy pulsed through it from the ESD. This energy concentration in a small area of a resistor's active element causes it to heat up, which could lead to irreversible damage. With the growing trend of miniaturization, electronic devices, including resistors, are becoming smaller and smaller, causing them to be more prone to ESD damage.
Pulse withstanding resistors, like Riedon's PCR series, are specifically designed to handle such large-volt discharges and are still available in small-package chip sizes.
In this past blog post, we mentioned Riedon’s product offering line for current sense resistors. As the need to measure the current flow in electronic systems is becoming more and more widespread, these are some of the type of applications where current sense resistors are readily being used:
Military and Aerospace: Sonar, surveillance equipment, satellites, missiles
Telecom: Cell phones, mobile radios, laptops, hand-held devices Medical and
Instrumentation: Pressure sensors, monitoring systems, implant products, electronic scales, diagnostic equipment
Automotive: Anti-lock brake systems, power steering, control systems, voltage regulators, information centers, engine controls
General Use: Battery-powered devices, Current direction controllers, or other high-voltage or precision applications.e: Anti-lock brake systems, power steering, control systems, voltage regulators, information centers, engine controls
Contact us today to discuss your project, we will be happy to assist you!
In the past 12 months, we have been engaged in many online and print publications. Our technical articles have been picked up by many US and international editorials. We increased our online traffic by 30% and received many new customers because of our engagement with the Technical/Engineering community.
Just in case you missed them when they were published, here is the list of some of the articles:
Riedon, a specialist manufacturer and supplier of cutting-edge, resistive solutions, enables electronic equipment designs capable of meeting the demanding requirements of medical and aerospace applications and operating in the extreme environments encountered in the oil and gas industries. Whether it is for magnetic resonance scanners, aircraft flight controls or down-hole instrumentation for oil wells, Riedon’s advanced CHR and HVS chip resistor technology delivers high-performance, high-temperature operation with resistance values up to 10TΩ.
The maximum continuous working temperature of standard components with nickel/tin terminals is usually specified as +155oC (tin has a peak temperature of 230oC while nickel is limited to 160oC). By using superior materials, and combining an inner terminal of silver/palladium with a wrap-around of platinum/silver, Riedon is able to offer chip resistors that can work in applications up to 300oC. This special termination technology confers several other advantages for demanding applications. In particular it is suitable for silver epoxy attachment, which provides the reliability and high temperature performance essential for the temperature probes and pressure monitoring devices used in oil and gas exploration.
Further, by avoiding nickel, these chip resistors are completely non-magnetic and can be used in the presence of strong magnetic fields, such as medical CT and MRI scanners. Similarly, no tin avoids the ‘tin-whisker’ problem that can be a concern in aerospace applications. Termination material also influences VCR (voltage coefficient of resistance), an important characteristic of high voltage resistors.
Riedon’s chip resistors are specifically designed to achieve low VCR. The CHR series of non-magnetic chip resistor provides resistance values from 1 Ohm to 10MΩ with power ratings from 0.05W to 1.5W, depending on package size (from 0402 to 4020). Various resistance tolerances are available, from as low as ±0.5%, along with TCRs (temperature coefficient of resistance) specified from ±50ppm/oC. The standard temperature range is -55oC to +155oC with the HT version extending to +300 oC. Riedon’s HVS series of high-voltage, high-temperature, thick film chip resistors addresses requirements for higher value resistors, from 100kΩ to 10TΩ, with operation up to 6000V. Again, power-rating options are available up to 1.5W with an HT version provides high temperature operation up to +300 oC. VCR is also specified across the range, starting from as low as 10ppm/V. “High value resistors, up to 10 Tera-Ohms, are a core competency for Riedon”, said Phil Ebbert, their VP of Engineering, “Some other manufacturers only deliver up to 10MΩ. This, combined with our ability to achieve high precision and stability over a wide temperature range, is what distinguishes these Riedon products.”
Current shunt is a resistor with resistance as low as 100 microOhm.
Riedon offeres comprehensive range of high-power current-sense resistive products and technologies for power management, safety systems and motor control applications. Whether your power electronics circuits need precision current-sensing capability, superior thermal performance or space-saving packages, rieodn has the right resistor for your application, including economical axial devices with ratings up to 5W; bare metal element, and through-hole styles, and or high current metal-element chip resistors. Call us so we can help you with your application needs.