LED driver uses a patented control method to eliminate audible noise

By Majeed Ahmad, contributing writer

The new LED backlight driver from Allegro MicroSystems employs the patented pre-emptive boost (PEB) control to eliminate the audible noise. The A8060x family of LED drivers uses PEB control to substantially reduce V_out ripple and thus eliminate the common problem of audible noise from ceramic output capacitors during PWM dimming.

That allows the lighting systems to achieve an LED brightness contrast ratio of 15,000:1 using PWM-only dimming at 200 Hz. Moreover, a higher contrast ratio of 150,000:1 is possible with a combination of PWM and analog dimming. Here, it’s worth noting that A8060x drivers boost PWM dimming ratios without analog adjustment.

The ALT80600  and A80603  LED drivers combine a switching converter with a MOSFET and four current sinks. They feature four LED strings, each capable of handling up to 120 mA with the total LED current of up to 480 mA. Next, the A80601  and A80602  devices drive an external boost FET for higher output power. And they provide a total LED current of up to 840 mA via four or six strings, respectively.

All of these devices can be configured in a boost or single-ended primary-inductor converter (SEPIC) topology to cover a broad range of application configurations.

In A8060x drivers, switching converters integrated to lower EMI feature programmable switching frequency, controlled switching slew rate, and programmable dithering. Additionally, a clock-out pin allows other switching converters to be synchronized to the A8060x switching frequency for enhanced EMI performance of the overall system.

The A8060x family of LED drivers supports all types of automotive backlighting, including audiovisual systems as well as instrument clusters and heads-up displays (HUDs). They also offer a host of safety and protection features required in automotive applications. The devices are housed in 4 × 4-mm QFN-24 wettable flank with exposed thermal pad packaging (ES suffix).