To facilitate hardware engineers in making the best use of Slkor products, provide comprehensive technical support, and create value for customers, Slkor introduces the SL-FW-TRS-5.5D1 temperature sensor application solution, including reference circuits and related schemes: The SL-FW-TRS-5.5D1 temperature sensor features high infrared responsivity, excellent repeatability, and high reliability. It is housed in a TO-39 metal can package. Inside the package, it integrates a MEMS thermopile sensor chip and a dedicated signal conditioning ASIC. The ASIC incorporates a 24-bit Sigma-Delta high-precision ADC, a low-noise instrumentation amplifier PGA, and interface circuits, along with a built-in high-precision thermistor chip for ambient temperature compensation. Product Features 2.1 Easy to implement – no user temperature calibration required 2.2 Direct temperature output – no external circuitry needed 2.3 Measurement distance: 30–50 cm 2.4 MEMS thermopile technology 2.5 High responsivity with fast response time 2.6 Standard I²C interface 2.7 TO-39 metal can package Figure 1 Precise temperature control is a critical safeguard for infant feeding. Slkor, with deep expertise in MEMS sensors and infrared temperature measurement as its core technology, brings non-contact measurement, high-precision sensing, real-time response, and intelligent energy-saving capabilities into bottle warmers/mixers, delivering a complete intelligent temperature control solution. This solution enhances product usability and safety redundancy while reducing overall system power consumption through a low-power architecture, providing modern families with a professional yet convenient parenting tool. Non-contact Measurement: Hygienic, Touchless Sensing Slkor’s infrared temperature sensor operates on radiation thermometry principles, acquiring milk temperature without physical contact. This approach eliminates cross-contamination paths inherent in contact-based thermometry and removes the maintenance burden of repeatedly cleaning the sensor probe. Users no longer worry about dead spots on the probe or reading drift due to poor contact. This non-invasive measurement paradigm reduces thermal latency and builds a cleaner protective barrier for infant health. High-Precision Temperature Measurement: Accurate Control, Nutrient Preservation Milk temperature directly determines nutrient retention and palatability. Slkor’s solution integrates a low-noise PGA, 24-bit Sigma-Delta ADC, and DSP calibration algorithms, ensuring accuracy throughout the signal chain from acquisition to output. Users can finely set target temperatures to suit formula preparation for different age stages – whether for newborn-sensitive formulas or high-nutrition formulas for growing infants – ensuring stable, ideal temperatures for the best feeding experience. Real-Time Feedback: Dynamic Temperature Visibility The sensor’s fast thermal response enables real-time temperature updates on the user interface. During mixing, users can continuously monitor the temperature curve on the screen and adjust dynamically as needed. This real-time feedback not only improves temperature control precision but also helps users quickly respond to fluctuations, ensuring the milk remains within the optimal range. Whether rapid heating or constant temperature maintenance, real-time measurement provides a safer and healthier feeding environment. Intelligent Energy-Saving Temperature Control: Adjust on Reach, Sleep on Standby The sensor works in deep coordination with the main control system: once the temperature reaches the preset threshold, it triggers power reduction or heating pause, preventing nutrient degradation or scalding risks from overheating. Under standby or low-load conditions, the system automatically switches to low-power mode to minimize wasted energy, balancing cost efficiency and environmental concerns. Local Alternative: Self-Reliant, Pragmatic Substitution The infrared temperature measurement market has long been dominated by European and American manufacturers, with German, Belgian and other companies leveraging patent barriers to maintain high pricing, while trade volatility increases supply chain risks for domestic players. Slkor, based on its own technology, achieves core specifications comparable to international mainstream levels and offers customized services including "sensor + algorithm + factory calibration" covering applications from maternal and infant appliances to industrial inspection. This approach optimizes cost structures while flexibly responding to differentiated needs through adaptable production lines, and has already achieved stable mass production in bottle warmers. For OEMs, it adds a reliable domestic option; for consumers, it means better product experience and more reasonable pricing – the value of technological independence ultimately materializes in the products themselves. The following figure shows the connection diagram of Slkor temperature sensor SL-W-TRS-5.5D1 (commercial grade, below 60°C) in a bottle warmer application: The following figure presents the temperature-grade performance parameters of the Slkor SL-W-TRS-5.5D1, classified by detection temperature range into industrial, medical, and commercial grades. More application scenarios for commercial, medical, and industrial grades are shown below: Slkor temperature sensor alternative brands and model equivalents are shown below: Slkor Semiconductor will continue to release a series of DEMO application products to facilitate end customers and distributors in using the "slkor" brand’s new products and to strengthen technical support services. Slkor – Chips Driven Future! Company Profile: The core technical members of Kinghelm and Slkor come from Tsinghua University and UESTC, and also include many overseas returnees. Kinghelm has been deeply engaged in microwave RF technology for nearly 20 years, with a central laboratory in Shenzhen fully equipped for independent R&D and testing, and a production base in Luzhai County, Guangxi, equipped with intelligent production lines capable of high-volume delivery. Products include Beidou/GPS antennas, Bluetooth and WiFi antennas, RF jumper cables, signal connectors, board-to-board connectors, board-end sockets and headers, switch series products, as well as custom medical and automotive wire harnesses, custom probe pins and connectors, and supporting services including drafting, mold development, testing, and mass production. "Slkor, Chips Driven Future" – Slkor treats colleagues and peers with sincerity, continuously driving industry development through new materials, technologies, products, and service models. Slkor’s main products include TVS diodes, transistors, MOSFETs, IGBTs, power management ICs, and three major series, along with new offerings such as Hall sensors, BMS, high-speed optocouplers, and passive crystals. Mr. Song Shiqiang founded Shenzhen Kinghelm Electronics Co., Ltd. and Shenzhen Slkor Semiconductor Co., Ltd. in Huaqiangbei, adhering to the corporate culture of "Integrity, Diligence, Resilience, Detail" and practicing the business ethics of "Fairness, Openness, Cooperation, Win-Win" for steady growth. Kinghelm and Slkor have now developed into globally recognized and reputable brands, serving over 40,000 customers worldwide with products and comprehensive technical services.

Shenzhen Slkor Micro Semiconductor Ltd. has technical backbone personnel from Tsinghua University. The company is led by new materials, new processes, and new products, mastering the internationally leading third-generation semiconductor silicon carbide (SiC) power device technology. Slkor is a high-tech enterprise integrating the design, development, production, and sales of electronic products, providing customers with reliable products and supporting technical services. 1.1 Name: Slkor SL27517A Driver MOSFET Solution 1.2 Application: Power tools, motor control, AC-DC converters, industrial control, etc. 2. Performance Parameter Benchmarking, Strong Compatibility 2.1 Symmetrical Drive Capability The Slkor SL27517A, a 4A single-channel gate driver, offers several significant advantages when replacing TI's UCC27517DBVR (Texas Instruments). The main benefits are reflected in performance compatibility, cost control, design flexibility, and supply stability. The Slkor SLkor SL27517A provides 4A sink/source peak current (symmetrical drive) at VDD=12V, fully consistent with the UCC27517's 4A source/sink current capability. It can efficiently drive power devices like MOSFETs and IGBTs, suitable for applications such as switching power supplies and DC-DC converters. The Slkor SL27517A achieves a wide voltage range, with an operating voltage range of 4.5V-20V, slightly better than the UCC27517's (TI) parameter of 4.5V-18V, offering stronger adaptability, especially in low-voltage or battery-powered scenarios (e.g., portable devices). 2.2 Low Delay and High-Speed Response The Slkor SL27517A features short propagation delay (typical 12ns) and fast rise/fall times (6ns/11ns), ensuring minimized switching losses, making it suitable for high-frequency applications like digital power supplies and GaN device driving. 3. Design Flexibility and Enhanced Safety 3.1. Dual Input Configuration and Power Consumption The Slkor SL27517A supports inverting (IN-) or non-inverting (IN+) input modes, flexibly adapting to different logic control needs through its dual-pin design, simplifying circuit design. 3.2 Floating Input Protection When the input pin is floating, the Slkor SL27517A output automatically latches low, preventing false triggering of the power transistor and enhancing system reliability. 3.3 Low Quiescent Power Consumption Very low quiescent current, making it particularly suitable for battery-powered or low-power consumption scenarios (e.g., solar equipment, UPS). 4. Typical Application of Slkor SL27517A in High-Power Driving Scenarios 4.1 Application Principle: The input modulation signal provides a PWM waveform to drive the Slkor PC817 optocoupler U2. Here, when the 24V pulse waveform is high, the optocoupler current is around 6mA (5V control can also be used by changing the current-limiting resistors R6 and R8). Optocoupler U2 is mainly for signal isolation. Its power is supplied by the DC-DC power management IC Slkor LM2596S-5.0 providing 5V. The external modulation signal can be provided by a PLC. D1 is a Slkor switching diode, here used for freewheeling; it protects optocoupler U2 when the modulation signal is reverse-connected. U1 is the gate driver chip Slkor SL27517A, a single-channel 4A high-speed low-side gate driver that can efficiently and safely drive MOSFETs and IGBTs. Features like low propagation delay, compact SOT-23 package, and very low quiescent current allow the MOSFET switching frequency to reach hundreds of kHz. This chip is very suitable for synchronous rectification driving in servers and communication power supplies, as well as industrial applications. 4.2 Suggestions from Slkor Applications for Engineers: The Slkor gate driver chip SL27517A in this circuit is powered by 12V. When pin 5 outputs high, it drives the MOS transistor Slkor SL142N06Q to turn on and drive the load. The Slkor MOS transistor SL142N06Q has a typical drain-source current of 20A at a gate drive of 10V, with a low on-resistance of 2.6mΩ, making it very suitable for high-speed switching control and synchronous rectification. The value of resistor R3 should be selected based on actual PCB wiring and layout; 100Ω is chosen here. R3 should be placed close to the gate of the MOS transistor, and the routing path should be short to reduce parasitic inductance. D3 is a switching diode primarily used to accelerate the turn-off of the MOS transistor; add it according to the actual situation. 5. The DEMO board corresponding to the Slkor SL27517A gate driver is shown below: Physical image of the Slkor SL27517A gate driver corresponding DEMO board 5.1 This DEMO board uses a double-layer PCB design. When the Slkor (/slkoric.com) SL27517A drives a parallel structure of high-power MOS transistors like the SL142N06Q, which can handle high current, the DEMO board increases the power copper pour area and uses double-sided copper pour for better heat dissipation and high current handling. CN2 and CN1 connect to the motor or laser pump. CN2 and CN3 connect to the switching power supply with a maximum voltage of 60V (can be connected to 12V-60V according to actual needs). The low delay characteristic of the Slkor SL27517A makes it widely used in PWM driving of high-power MOS transistors. The DEMO board features the Slkor brand logo; users can scan the code to follow the latest developments from Slkor Semiconductor. 6. Slkor SL27517A Gate Driver DEMO Board BOM Information is as follows: No. Quantity Comment Designator Manufacturer 1 1 470uF C1 2 1 1uF C2 3 1 220uF C3 4 3 T44007 CN1,CN2,CN3 5 2 1N4148W D1,D3 Slkor 6 1 ES2D D2 Slkor 7 1 SS34 D4 Slkor 8 2 PZ254V-11-02P H2,J1 9 1 33uH L1 10 2 SL142N06Q Q1,Q3 Slkor 11 3 10kΩ，0603 R2,R7,R11 12 1 100Ω，0603 R3 13 2 10mΩ，2728 R4,R13 14 2 2kΩ，0603 R6,R8 15 1 4.7kΩ，0603 R9 16 1 0Ω，0603 R10 17 1 PC817C U2 Slkor 18 1 LM2596S-5.0 U4 Slkor 19 1 SL27517A U5 Slkor Slkor Semiconductor (/slkoric.com) provides corresponding DEMO boards for end customers and distributors to facilitate the use of new "Slkor" brand products and to enhance supporting technical services for customers. Everyone is welcome to contact Slkor Customer Service Ms. Xie (0755-8304 4319) to receive them for free!

Slkor's technical team hails from Tsinghua University. As a National High-Tech Enterprise, Slkor developed silicon carbide power devices relatively early and has grown into a company integrating R&D, design, sales, and application technical services. Its corporate culture is inclusive, open, and innovative. The "SLKOR" brand has gained international recognition and reputation, with market share continuously rising, and has obtained certifications including ISO9001, RoHS, REACH, and California Proposition 65. Slkor has R&D institutions in Beijing and Suzhou, with a laboratory and central warehouse at its Shenzhen headquarters. Main product lines include diodes & transistors, power devices, and power management ICs. The company is progressively developing new products like Hall sensors, ADCs, BMS, high-speed optocouplers, and passive crystals. These are applied in industries such as smartphones, laptops, robotics, power tools, connected vehicles, 3C digital products, and the Internet of Things, collaborating with over ten thousand partners worldwide! The Slkor official website has been developed into a platform for learning and exchange within the semiconductor industry, creating an industrial ecosystem in cyberspace to serve the company's operational development. The company's vision is to become a "Semiconductor Leader" through three decades of relentless effort by its colleagues! 1.1 Name: Application Circuit Solution for Slkor SL4139 Driver Chip 1.2 Applications:Automotive electronics, GPS navigation systems, Portable Multimedia Players (PMP), handheld devices, constant current drivers, decorative lighting. 2. Package: The chip uses a small SOT23-5 package. 2.1 Product Features The SL4139 is a DC/DC boost converter designed to provide a constant and precise drive current for multiple LEDs.With a fixed switching frequency of 1MHz, the SL4139 can be used with small external ceramic capacitors and inductors. The adjustable current, set by an external resistor R1, allows the SL4139 to drive several LEDs connected in series. The SL4139 is suitable for driving LEDs of the same type, capable of driving up to 9 white LEDs in series or handling a maximum drive voltage of 32V. LED brightness can be adjusted using a DC voltage, a logic signal, or a Pulse Width Modulation (PWM) signal. The Shutdown control pin (SHDN) allows the device to operate in a shutdown mode with extremely low quiescent current. 2.2 Maximum drive voltage: 32V; LED open-circuit overvoltage protection; Maximum power conversion efficiency: 90%. 3.0 1MHz fixed frequency with low noise. 3.1 Shutdown current < 10uA. 3.2 Undervoltage Lockout (UVLO) threshold: 3.3V. 3.3 Operating temperature range: -40℃ to +85℃. 4. Slkor SL4139 White LED Driver Application Circuit 5. Application Principle 5.1 Power is supplied via a Kinghelm (KH) 16-pin Type-C connector, outputting 5V to the SL4139. After DC/DC boosting by the SL4139, a constant LED drive current is provided to illuminate the LEDs. The SL4139 is a fixed-frequency (1MHz), low-noise, inductive boost converter that provides a constant current with excellent linearity and load regulation. The device uses a high-voltage NMOS switch between the SW pin and GND to drive the inductor. When the NMOS switch is off, energy stored in the inductor is released to the load through the Schottky diode. The duty cycle of the NMOS switch is internally adjusted and controlled based on the feedback voltage at the FB pin, ultimately regulating the FB pin voltage to a constant 0.3V. The current flowing through the LED is inversely proportional to the resistor value (I = 0.3V / R1). 5.2 The SL4139 includes an over-temperature protection circuit. When the junction temperature exceeds 150℃, the device automatically stops operating until the temperature drops to 130℃, at which point normal operation resumes. 5.3 In case of an LED open circuit, the feedback control loop opens, causing the output voltage to continuously increase. Once the output voltage exceeds 37V, internal protection circuitry activates, placing the device into a low-power safe operating mode. 5.4 The SL4139 can be applied in GPS navigation systems, portable multimedia players, handheld devices, lighting, constant current drivers, etc. 5.5 For a specific application reference, please see the Ring Light DEMO board below: 6. Suggestions from Slkor Applications for Engineers: The SL4139 is a high-frequency switching regulator. To reduce EMI, ripple, and noise, the PCB traces carrying high-frequency switching currents must be laid out carefully. The bold lines in the figure above indicate the paths of the high-frequency switching currents. All these traces should be short and wide to minimize parasitic inductance and resistance. In the figure below, Loop ① is the current path when the internal SL4139 switch is closed. Loop ② is the current path when the internal SL4139 switch is open. The areas of both loops should be kept as small as possible. 7. BOM (Bill of Materials) Information for the Slkor LED Driver Chip SL4139 DEMO Board is as follows: Slkor Semiconductor, in order to facilitate end customers and distributors in using the "slkor" brand's new products and to strengthen supporting technical services for customers, provides detailed product information. Please consult our personnel!

Slkor's technical team comes from Tsinghua University. The company is a national high-tech enterprise that developed silicon carbide power devices early on and has grown into a company integrating R&D, design, sales, and application technical services, with an inclusive, open, and innovative corporate culture. The "SLKOR" brand has gained international recognition and reputation, with continuously increasing market share, and has obtained ISO9001, RoHS, REACH, California 65, and other certifications. Slkor has R&D institutions in Beijing and Suzhou, and its Shenzhen headquarters includes a laboratory and central warehouse. The main products include three major series: diodes and transistors, power devices, and power management chips. New products such as Hall sensors, ADCs, BMS, high-speed optocouplers, and crystal oscillators are gradually being introduced. These products are used in smartphones, laptops, robots, power tools, telematics, 3C digital products, AIoT, and other industries, cooperating with more than 10,000 global partners! "Slkor Micro Chips Driven Future". Slkor's official website has been built into a platform for semiconductor peers to learn and exchange ideas, creating an industrial ecosystem in cyberspace to serve the company's operation and development. The company's vision is that after 30 years of unremitting efforts, colleagues will make Slkor a "leading enterprise in the semiconductor industry"! 1.1 Name: Slkor DW03 Lithium Battery Protection Application Solution 1.2 Application: Single-cell lithium-ion battery pack; lithium polymer battery pack 2. The chip comes in a SOT23-5 package. 2.1 Product Features The DW03 product is a highly integrated solution for protecting single-cell lithium-ion/lithium polymer rechargeable battery packs. The DW03 includes an advanced power MOSFET, high-precision voltage detection circuits, and delay circuits. The DW03 provides all necessary battery protection functions such as overcharge, over-discharge, overcurrent, and short circuit, with very low power consumption during operation. This chip is not only designed for mobile phones but is also suitable for all kinds of information products that require lithium-ion or lithium polymer rechargeable batteries for long-term power supply. 2.2 The DW03 monitors battery voltage and current, and protects a single-cell rechargeable lithium battery from damage due to overcharge voltage, over-discharge voltage, overcharge current, over-discharge current, and short circuit by disconnecting the charger or load. The system has a simple external circuit. The MOSFET is built-in, with a typical equivalent resistance of 65m&Omega;. 3.1 Charger detection; 0V battery charging function; internally set delay time; high-precision voltage detection. 3.2 Low quiescent current: Normal operating current: 2.8uA; Standby current: 1.5uA; RoHS and lead-free compliant. 4. Slkor DW03 Lithium Battery Protection Application in Electric Shaver Solution: Figure 1 Figure 2 Figure 3 Application Principle Slkor single-cell lithium battery protection DW03. The DW03 includes an advanced power MOSFET, high-precision voltage detection circuits, and delay circuits, and is widely used in small household appliances. In the shaver application circuit shown in the figure, USB Type-C supplies power to charge the single-cell lithium battery. During charging, the MCU's ADC I/O port collects the charging voltage and displays the battery level on a digital tube. The charging circuit is built with Slkor SL4056 charging management and simple peripheral circuits. In the motor drive section, Slkor 3400 MOSFET is used, and the MCU I/O port collects key signals to control the motor on/off. DRV is the gate drive signal. When the MCU detects that the key is pressed, DRV outputs a high level and the shaver starts to rotate. 5.1 Figure 1 is only a reference circuit for the MCU to collect lithium battery charging. Note that the DW03 connects to the positive terminal of the lithium battery through a 100R resistor, pin 2 of the chip connects to the negative terminal of the lithium battery, and pins 4 and 5 connect to GND. Users can follow the specifications to design and easily build a corresponding single-cell lithium-ion battery protection circuit. The DW03 protects a single-cell rechargeable lithium battery from damage due to overcharge voltage, over-discharge voltage, overcharge current, over-discharge current, and short circuit. If no abnormal conditions are detected, the output transistor remains on, and charging and discharging can switch freely. This is called normal operation mode. During normal discharging, when the battery voltage drops below the over-discharge detection voltage (VDL) and the duration reaches or exceeds the over-discharge voltage detection delay time (TDL), the DW03 disconnects the battery from the load and stops discharging. This is called over-discharge voltage condition. In normal operation mode, when the discharge current is equal to or higher than the set value (VM voltage is equal to or higher than the overcurrent detection voltage) and the duration reaches the over-discharge current detection delay time, the DW03 turns off the discharge FET and stops discharging. This is called over-discharge current condition. During normal charging, if the VM voltage drops below the charge detection voltage (VCHA) and the duration exceeds the overcharge current detection delay time (TCU), the DW03 turns off the charge FET and stops charging. This is called abnormal charge current detection, etc. 5.2 In Figure 2, the bidirectional TVS for surge protection is Slkor SMF5.0CA, with VRWM voltage of 5.0V and excellent clamping capability, with a peak pulse power capability of 200W under 10/1000 &micro;s waveform. Q2 and Q4 are both Slkor MOSFETs. The MCU enable signal controls Q2 to turn on Q4, and after Q4 conducts, Type-C outputs voltage VCC to power the load. 5.3 In Figure 3, D4 and D5 mainly serve as a battery and Type-C power switching circuit. When the charger is unplugged, the lithium battery supplies power. D4 and D5 are Slkor 1N5819WT Schottky diodes, with reverse leakage current of 1uA, voltage rating of 40V, maximum forward current of 1A, and low forward voltage drop, making them very suitable for low-current applications such as MCUs. 6. Slkor DW03 Lithium Battery Protection Application BOM Table Information is as follows: Slkor Semiconductor provides end customers and distributors with convenient access to new products under the "Slkor" brand, strengthens technical support services for customers, and offers detailed product information. Please consult our staff for more details.

Efficiently managing the power requirements of multi-cell battery applications is a critical design challenge. Slkor Micro's SL3763 standalone linear battery charger IC presents a robust and integrated solution tailored for 3-cell Li-Ion batteries. Capable of delivering up to 4A of charging current and incorporating essential features like automatic recharge and sleep mode, it simplifies design while ensuring reliability. This document delves into the SL3763's operation, provides a detailed typical application circuit for solar-powered lighting systems, and offers practical PCB layout guidelines to maximize performance. Discover how the SL3763 can serve as the cornerstone of your next portable industrial, medical, or backup power design.

Slkor's SL1609 Hall Element delivers ultra-low power consumption (<3.3μA) and omnipolar detection for precise, non-contact switching. Ideal for TWS earphones, laptops, power tools, and industrial automation, it enables smarter, more efficient designs with high ESD protection and flexible magnetic thresholds.

Slkor's SL1609 Hall Element delivers ultra-low power consumption (<3.3μA) and omnipolar detection for precise, non-contact switching. Ideal for TWS earphones, laptops, power tools, and industrial automation, it enables smarter, more efficient designs with high ESD protection and flexible magnetic thresholds.

Slkor’s SL27517A reduces BOM cost by 30% vs. TI UCC27517 while extending voltage range to 20V for battery-critical applications.

In an effort to strive to provide customers with a full range of complementary products, SLKOR has launched a series of user manuals for the demo boards of digital infrared thermopile non-contact temperature measurement application designs.

The core technical personnel of Shenzhen SLKOR Micro Semicon Co., Ltd. are from Tsinghua University and Yonsei University in South Korea. They lead the company's development with new materials, new processes and new products, and have mastered the internationally leading third-generation semiconductor silicon carbide power device technology relatively early.

To help customers make the most of SLKOR's products, the company has recently introduced the SL-W-TRS-5.5Dx digital infrared thermopile chip and its associated application solutions, offering comprehensive technical support. The technical team at Shenzhen SLKOR Micro Semicon Co., Ltd. comes from Tsinghua University and Yonsei University in South Korea, leading the company with new materials, processes, and products. They have mastered internationally advanced third-generation silicon carbide power device technology early on. SLKOR is a high-tech enterprise integrating electronic product design, development, production, and sales, providing reliable products and technical services to its customers. With rapid development, the company is introducing more new products to serve customers and make a positive contribution to the semiconductor industry, striving to become a "semiconductor leader."

Small relays are commonly used in electronic systems to control circuit switching, and they have widespread applications in industrial equipment, instruments, and household appliances. The heart of modern control circuits is usually computer chips such as MCUs, DSPs, and FPGAs. These core chips do not have enough output power to directly control small relays and can be driven by SLKOR's small transistors BC817-25, BC848B, BC847B, and small MOSFETs 2N7002E, SL2302S, SL2300, SL3400, SL3402, and Darlington arrays ULN2001D, ULN2003AU, ULN2803AS, etc. In the following example, we will use the driving of a small high-power relay JQC-3FF/12VDC-1ZS (551) from HF as an example. The coil of the relay has a rated voltage of 12V, an action voltage of 9V, a maximum voltage of 15.6V, and a coil resistance of 400Ω. When powered by 12V, the coil current is 30mA. Here we will introduce the design of driving the small relay using BC848B, SL2302, and ULN2803AS, respectively. Taking the STM32F030C8T6 MCU as an example, any IO pin can provide a maximum limit of 25mA of pull-up or pull-down current, and the total limit of pull-up or pull-down current for all IO pins is 80mA. Therefore, when applying the IO pins, there should be enough margin. The typical value of the weak pull-down resistor for the IO pin is 40KΩ. When powered by 3.3V, if the IO pin outputs 8mA of current, the minimum output high level is 2.9V, and if the IO pin pulls 8mA of current, the maximum output low level is 0.4V.

The Slkor 4056 is a low cost linear battery charger for single cell lithium-ion batteries. It has a CC/CV charge profile required for Li-Ion battery. Charge current and charge time are set externally with a single resistor and capacitor, respectively, the maximum charging current can reach 1A. The SL4056 has two open-drain output pins for status indication, namely the charging status indicator pin (CHRG) and the battery fully charged indicator pin (STDBY). The power MOSFET circuit inside the chip automatically reduces the charging current when the junction temperature of the chip exceeds 135℃. This feature allows users to maximize the utilization of the chip for charging without worrying about overheating and damaging the chip or external components. The Slkor? SL4056 is available in a ESOP8 package.

The Slkor® SL4054 is a complete constant-current/constant-voltage linear charger for single cell lithium-ion batteries. Its SOP package and low external component count make the SL4054 ideally suited for portable applications. Furthermore, the SL4054 can work within USB and wall adapter. No blocking diode is required due to the internal PMOSFET architecture and have prevent to negative Charge Current Circuit. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The SL4054 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. When removing input power automatically puts the SL4054 into a low current mode to reduce the battery's leakage current to below 2uA, and the shutdown mode reduces supply current to 45μA. SL4054 Other features include current monitor, under voltage lockout, automatic recharge and two status pin to indicate charge termination and the presence of an input voltage. The Slkor? SL4054 is available in a SOT23-5 (ThinSOTTM) package.