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.
High Ohm Resistors In A Small Package Size When trying to analyze very low electronic signals, a stable, high ohm resistor is required. With thick film technology, very high values (up to 10 Tera-Ohms!) can be achieved in smaller and smaller package sizes. With thick films, the conduction mechanism is a combination of metallic and semiconductor conductivity and a mixture of metal and glass/organic binders is screen-printed onto a ceramic base and then fired at 850°C. A precise mixture of these particles will yield a resistor that is not only very stable, but also has quite low temperature coefficient (TCR) and voltage coefficient (VCR) ratings.
The resistors then utilize laser-cut trimming to make the resistor value as precise as possible, and tolerances down to 0.5% can be achieved, depending on how high the ohmic value is.
Check out Riedon's HVC Series with resistance ranges from 10 Mohm to 1 Tohm in package sizes as low as 0402. Click here.
Or for higher-temperature and/or higher voltage applications, our HVS series is also available with an operating temperature up to 300°C. Click here.
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!
Riedon has designed chip resistors for 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 +155˚C (tin has a peak temperature of 230˚C while nickel is limited to 160˚C).
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 300˚C.
This termination technology 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.
The CHR series of non-magnetic chip resistors provides resistance values from 1Ω to 10MΩ with power ratings from 0.05W to 1.5W, depending on package size (from 0402 to 4020).
The HVS series of higher value resistors runs from 100kΩ to 10Tohm, with operation up to 6,000V.
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: