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!