Our advantages

Chinese manufacturing processes have undergone years of iteration, resulting in mature and reliable technologies. Many international corporations opt for production outsourcing in China.  As an electronic components manufacturer in China, our products can fully replace those of major international brands in 99% of applications without the need for testing verification. Our products boast high consistency in quality, reasonable pricing, ample inventory, flexible supply, short lead times, and professional after-sales service.

Slkor alternative equivalents to Onsemi.

SL4139 is a DC/DC boost converter that provides precise constant current drive for multiple LEDs. With a fixed switching frequency of 1MHz, SL4139 can be paired with small external ceramic capacitors and inductors. Adjustable current, set by external resistor R1, allows SL4139 to drive series-connected LEDs. It is suitable for driving LEDs of the same type, with up to 9 white LEDs in series or a maximum driving voltage of 32V. LED brightness can be adjusted using a DC voltage, logic signal, or pulse width modulation (PWM). The shutdown control pin (SHDN) enables the device to operate in ultra-low static current standby mode.In addition to thermal protection and overcurrent limiting, SL4139 enters ultra-low power mode in the event of LED open-circuit faults. The chip is packaged in a small SOT23-5 form factor.

Features

● Switch peak current: 1A

● Maximum driving voltage: 32V

● Maximum power conversion efficiency: 90%

● Shutdown current less than 10uA

● Fixed frequency of 1MHz with low noise

● Surge current limitation during soft start

● LED open-circuit overvoltage protection

● 3.3V undervoltage lockout (UVLO)

● Overtemperature protection

● Suitable for automotive electronics

● RoHS compliant

● Industrial grade (-40°C to +85°C)

Application

● SL4139 is a fixed-frequency (1MHz), low-noise, inductor boost converter that provides constant current with excellent linearity and load regulation. The device utilizes a high-voltage NMOS switch between the SW pin and GND pin to drive the inductor. When the NMOS switch is turned off, energy stored in the inductor is discharged to the load through a Schottky diode.

● The duty cycle of the NMOS switch is adjusted and controlled internally based on the feedback voltage at the FB pin, ultimately outputting a constant regulation voltage of 0.3V at FB. The current flowing through the LED is inversely proportional to the resistance value (I = 0.3V/R1).

● During initial power-up, the duty cycle of the internal NMOS switch is limited to restrain surge current, providing a soft-start operation.

● In the event of an LED open circuit, the feedback control loop opens, causing the output voltage to continue increasing. Once the output voltage exceeds 37V, internal protection circuits activate, placing the device into a low-power safe mode.

● The device includes over-temperature protection circuitry that disables operation automatically when the junction temperature exceeds 150°C, and resumes normal operation once the temperature decreases to 130°C.