With the continuous improvement of LED light output, color and white high brightness LED can replace incandescent lamp for automobile lighting. Since LED is a low-voltage device, its forward voltage may be between 2 V and 4.5 V according to different color and current; LEDs also need to be driven with a constant current to ensure the required light intensity and color. Ansenmey Semiconductor provides rich LED lighting and motor drive solutions that meet the strict requirements of automotive applications to meet the needs of different automotive lighting applications.
Automobile headlamp scheme
Most cars on the road are now equipped with halogen lamps with main headlamp functions – high beam and low beam. The power consumption of the halogen low beam lamp is about 55 W, providing a light output of about 1000 lumens. The high intensity gas discharge lamp (HID) launched ten years ago consumes about 35 W and has an optical output of about 3500 lumens. Due to the extremely high light intensity and glare, it will bring risks to oncoming cars. Some countries require that the low beam lamps should be adjusted automatically and attached with high-pressure cleaning devices. Over time, HID lamps will integrate the high beam function in the Bi xenon scheme.
Although halogen lamp technology is still a feasible headlamp scheme, automotive design has begun to use LED lighting technology more and more to provide rich modeling options, support “instant conduction” of lamps and realize 0% to 100% brightness control.
Another important use of headlamps is the beam rotation of adaptive headlamp system (AFS) to optimize corner visibility, and the adaptive driving beam (ADB) of the beam is adjusted according to the real-time environment. Stepper motor provides main control functions for AFS and ADB. Ansenmey Semiconductor provides a complete product series specially designed for headlamps, including general bulb driver scheme, stepping motor driver, LED driver and xenon lamp driver.
1) Horizontal and rotary adjustment scheme of headlamp
Amis-30623 single chip micro stepping motor driver controller and Lin interface can be used to design a special electromechanical scheme for remote connection with Lin host. The device receives the position command through the bus, uses the configurable current, speed, acceleration and deceleration parameters to drive the motor coil to the required position, and can also detect the motor stalling condition. It is suitable for headlamp horizontal adjustment and rotation control.
Ncv70521 and ncv70522 are single chip micro stepping motor drivers with current conversion meter and SPI interface. Ncv70522 also includes embedded 5 V voltage regulator and watchdog reset function. The device is used as a peripheral driver to receive the “next microstep” command from the microcontroller and synchronize the motor coil current at the desired speed. The integrated SPI bus allows parameter setting and diagnostic feedback.
2) Power ballast and dual LED driver for advanced LED headlamp system
The ncv78663 single chip intelligent LED driver for headlamps supports the control of high beam, low beam, daytime running lights, position lights, turn signals, turn indicators and fog lights with a single module. It integrates digital dimming, SPI programmable settings and built-in diagnostic functions to provide an integrated energy-efficient scheme to fully control the headlamps.
Ncv78663 is an LED current regulator with step-down boost topology. It has the characteristics of constant average current, high-energy integrated step-down switch (high side), current up to 2a, extended diagnosis function (detection of open circuit or driver fault, short circuit, overcurrent protection, single LED fault) and thermal protection.
Tail lamp scheme
Nowadays, LED lamp body group is more and more used in automobile combined tail lamp (RCL), which not only has beautiful appearance and high luminous efficiency, but also helps the rear vehicle to clearly see the driving state of the front vehicle. Ansenmey semiconductor’s ncv7680 is a linear current regulator and controller for automobile LED combined tail lamp. It has the characteristics of driving LED string constant current output, LED string open circuit diagnosis (with open drain output), distortion rate control function to eliminate EMI concerns, on-chip 1 kHz tail edge PWM dimming, reducing output power in case of overvoltage and overtemperature, etc.
The voltage fluctuation range of automotive battery system is large. Providing constant LED light output under low voltage is the key characteristic. Ncv7680 contains 8 linear programmable constant current sources. The system using ncv7680 can support two brightness levels, one for brake lamp and one for tail lamp; Optional PWM control (preferred LED dimming method) can also be used. The fixed frequency of PWM generator can provide flicker free lighting. The optional external ballast FET allows power distribution in designs requiring high current.
In order to match the common LED string combined tail lamp configuration, ncv7680 provides 8 matching outputs to drive each string separately, and the current is set by a single resistor. Driving each string separately can ensure balanced current distribution between different strings. Ncv7680 can be used alone or together with other supporting circuits to form a more complex system. The device is suitable for combined tail lamp, daytime running lamp (DRL), fog lamp, central high mounted stop lamp (CHMSL) array, turn signal lamp and other external modulation applications, liquid crystal display (LCD) backlight, lighting module, etc.
Automobile interior and exterior lighting scheme
1) Internal RGB LED lighting scheme
Local interconnect network (Lin) bus is a low-cost serial communication protocol used in today’s automotive network architecture. Ncv7430 Lin RGB LED driver combines Lin transceiver with RGB LED driver and memory, which is suitable for automotive interior lighting. This single-chip RGB driver can monitor special multi-color LED applications in automotive interior lighting.
Ncv7430 includes Lin interface (slave device) for setting LED color and light intensity parameters. The device receives instructions through the LIN bus and then drives the LED independently. Ncv7430 is used as a slave device on the LIN bus, and the master device can read specific status information (parameter value and error flag) through the bus. The Lin address of ncv7430 can be programmed and solidified through the internal memory of the device.
The features of ncv7430 also include protection and diagnostic overcurrent detection (short circuit detection to ground and VBB, led open circuit detection, high temperature warning, shutdown and retry mode when an error is detected); Power saving (sleep mode power supply current 20 mA, compatible with 14 V automotive system); And EMI compatibility (LIN bus integrated ramp control, led modulation mode reduces EMC).
2) Constant current regulator (CCR) scheme for external and internal lighting
Dual terminal linear constant current regulator (CCR) is a simple, economical and strong device, which provides an effective current stabilizing scheme for cost sensitive LED applications. It is suitable for Automotive External lighting, such as central high mounted stop lamp (CHMSL), as well as internal lighting, such as cabin lamp, vanity mirror lamp and glove box. The device does not require external components, and can be used as high side or low side current regulator to stabilize the output current under a wide input voltage range. Its design has the characteristics of negative temperature coefficient, which is used to protect the LED from the influence of thermal runaway under extreme voltage and working conditions.
The steady current of devices with models of nsi45xxx, nsi50xxx, nsic20xx, nsi45xxxj and nsi50150ad can provide constant brightness in a wide voltage range; Negative temperature coefficient can protect led under high ambient temperature; Various maximum voltage versions (45 V, 50 V and 120 V) are available, which can withstand the sudden drop of battery voltage.
In addition to the above schemes, ansenmey semiconductor also provides other LED driving schemes. The compact 350 Ma step-down LED drivers cav4201 and cat4201 adopt a patented average current stabilizing architecture. Up to 7 LEDs in series can be driven by 24 V power supply to deal with 40 V transient voltage, and the energy efficiency is higher than 94%; It also has the functions of limited current and overheating protection and led open circuit protection. Its vehicle version cav4201 has passed aec-q100 certification. Another multi topology constant current switching regulator ncv3065 for high brightness LED, with driving current up to 1.5 A, adopts external switch to improve energy efficiency, supports PWM and analog dimming, and can withstand transient voltage up to 40 v.
Ansenmey Semiconductor provides various advanced solutions for automotive lighting applications by using low-voltage and high-voltage technology, expertise and technology in power management solutions, as well as advanced automotive technology. All these integrated circuits meet the specifications and environmental protection requirements such as automobile reliability and temperature. At the same time, they can meet people’s higher and higher requirements for interior lighting control, headlamp, rear combination lamp, fog lamp, clearance lamp, especially new light source. They not only bring comfort and fun to drivers and enrich consumer experience, but also meet the requirements of environmental protection and energy saving.
Source; Led network