October 27, 2020

Runic’s Chip Solution in the Fight Against Covid-19

5 min read
Covid-19 popped up and spread too quickly for humans to respond effectively. Its impact has...

Covid-19 popped up and spread too quickly for humans to respond effectively. Its impact has swept the world and its damage will be remembered for years to come. Several months after its outbreak, the pandemic is still not under control and continues to spread widely.

In this battle against the virus, IC chips have become an important component providing technical support for epidemic surveillance, virus testing, and medical treatment. The development and implementation of these chips requires the cooperation between different corporations and could see a significant increase in China’s chip industry.

Covid-19 broke out in China in late December 2019 and rapidly spread. Demand for testing equipment increased sharply and overwhelmed the supply. An increase in testing equipment is badly needed. IC chips are a basic component of many types of testing equipment and have become indispensable. However, the international IC brands couldn’t support the urgent lead time demand and quick solutions were needed to meet the needs to fight the pandemic. Some Chinese local IC chip original factories and technology companies have increased production to meet this need. Thanks to the rapid detection of infected patients and the government’s decisive actions, the pandemic has been successfully controlled within China.

Runic Technology, a chip design company integrated with R&D, production, and sales, has become the related items’ top 2 supplier for China’s medical equipment. The chips are used in handheld infrared thermometers and blood oximeters for pandemic surveillance and virus testing.

Schematic block diagram of the handheld infrared thermometer, which uses an analog thermopile probe

In the image above, a high-voltage LDO RS3002 is used to convert the 9 V from a batter to 3 V, which provides power for the whole system, such as the MCU, LEDs, op-amps, and more. Then a low-power-consumption LDO RS3236 is used to step down from 3 V to 1.5 V. The function of this is to provide a reference voltage for the thermopile, expanding its temperature-detecting range. In order to calculate accurately under different environmental temperatures, the MCU needs to read the current environment temperature and calculate the voltage of the NTC resistance and the 100-KΩ resistance divide voltage in the thermopile. The thermopile’s output resistance is high, so the topology of the amplifier part suit adopt in-phase amplifier, the magnifying power is needed to be approximately larger than 100 times, which needs a reserve low-pass filter to reduce the output noise. In order to maximize the resolution of the temperature, the 1/f noise of the op amp needs to be less than 5 uVpp and the DC offset voltage needs to be less than 10 uV. The op amp RS8551 in the block diagram above is a self-stabilized, zero-drift op amp developed by Runic. It has an ultra-low offset voltage and is very suitable for DC or low-frequency signal amplification. The main parameters are as follows:

  • Wide voltage supply range: 2.7 V to 5.5 V
  • High gain bandwidth: 4.5 MHz
  • Rail-to-rail input and output
  • Ultra-low offset voltage: 1 µV typical, 5 µV max.
  • Input offset drift (TC of VOS Typ): 0.005μV/˚C
  • High gain, CMRR, PSRR: 130 dB
  • Extended temperature: –40 ˚C to +125 ˚C
  • No external capacitor required
  • Many packages, such as SOT-23, SOP-8(SOIC-8), and MSOP-8

Runic can also supply high-input-voltage LDO and low-input-voltage LDO with excellent performance — RS3002 series and RS3226 series.

The main features of Runic RS3002 are as follows:

  • Wide input voltage range: 2.5 V to 36 V, which is popular used in the 9-V battery input application
  • Output current: 150 mA
  • Ultra-low quiescent current: 2.5 µA
  • Low voltage drop: 10 mV/mA
  • Ultra-high PSRR: 54 dB/1kHz
  • Output voltage precision optional: 1% or 2.5%
  • Kinds of fixed-output voltage and many packages, such as SOT-23, SOT-89-3, and SOT-23-5

The main features of Runic RS3226 are as follows:

  • Wide input voltage range: 1.7 V to 7.5 V, support four-cell dry battery input application
  • Internal max output current limit: >500 mA
  • Ultra-low quiescent current: 20 µA
  • Ultra-low drop voltage: 1 mV/mA
  • Ultra-high PSRR: 70 dB/Hz
  • Output voltage precision optional: 1% or 2.5%

Kinds of fixed-output voltage and many packages, such as SOT-23, SOT-89-3, SOT-23-5, and UTDFN-1*1-4L

Typical schematic block diagram of portable finger clip oximeter

In the image above, the Runic analog switch RS2105 is used to switch red LED and infrared LED lamps. They are time-sharing and modulate at a certain frequency. The op amp RS321 works with the DAC inside the MCU to produce a constant-current output signal. Because the constant-current operation of the LED lamp can obtain a relatively stable wavelength, the emission current usually reaches tens of mA, so the on-resistance of the analog switch should be less than 1Ω, and the on-resistance of Runic’s RS2105 is 0.6Ω, which meets the application’s requirement.

On the side of the photosensitive receiver, the op amp RS622 is used for the photoelectric conversion, which requires the input bias current of the op amp to A-level, and the bandwidth of the op amp needs to be more than 5 MHz to satisfy the fast response. The low-noise series op amps can better improve the resolution of the system. In the power topology, one is used for two-cell dry batteries (3 V) to boost the voltage to 5 V and then provide for the system circuit to use; the other is used for lithium batteries, which can be charged in cycles. The low-power-consumption LDO RS3236 is suitable for both topologies.

The main features of Runic’s low-noise op amp RS622 are as follows:

  • Wide voltage supply range: 2.5 V to 5.5 V
  • Low offset voltage: 0.7 mV typical, 3 mV max.
  • Low temp shift: 2 µV/˚C typical
  • Low input bias current IB: 1 pA
  • Gain bandwidth: 7 MHz
  • Quiescent current: 600 µA per channel
  • Noise factor: 11 nV/√Hz

The main features of Runic’s analog switch RS2105 are as follows:

  • Wide voltage supply range: 1.8 V to 5.5 V
  • Low on-resistance: 0.6Ω, 1Ω
  • Output current continues: 500 mA
  • –3-dB bandwidth: 30 MHz
  • Quiescent current: less than 1 µA
  • Has MSOP-10 and TDFN-3*3-10L packages

The main features of Runic’s low-consumption LDO RS3236 are as follows:

  • Wide input voltage range: 1.7 V to 7.5 V, support four-cell dry battery input application
  • Internal max output current limit: >500 mA
  • Ultra-low quiescent current: 20 µA
  • Ultra-low drop voltage: 1 mV/mA
  • Ultra-high PSRR: 70 dB/Hz
  • Output voltage precision optional: 1% or 2.5%
  • Kinds of fixed-output voltage and many packages, such as SOT-23, SOT-89-3, SOT-23-5, and UTDFN-1*1-4L

The pandemic is still going on, and there is no reliable vaccine or other effective eradication measure. The war against Covid-19 is under way and needs various industries’ cooperation, including the IC chip industry. During this time fighting against the pandemic, Runic has earned a high reputation with same as world-class IC producer’s high performance and good functionality, but with quicker results, lower price, and more flexible lead time. We are willing to provide our support and service to old and new partners from all over the world. Anyone who is interested in our products or would like to learn more are welcome to contact us.

Website: www.run-ic.com

Email: jim.wang@run-ic.com

Cheney Dong, sales director of Runic Technology

The post Runic’s Chip Solution in the Fight Against Covid-19 appeared first on EETimes.

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