MAX25169 150 mA Backlight Driver

ADI's MAX25169 is a highly integrated TFT power supply and LED backlight driver IC for automotive TFT-LCD applications. This IC integrates one boost converter, one inverting buck-boost converter, two gate-driver supplies, and a boost/SEPIC controller that can power one to six strings of LEDs in the display backlight. It is available in a 7 mm x 7 mm, 48-pin TQFN package with an exposed pad and operates over the -40°C to +125°C ambient temperature range. The MAX25169 evaluation kit (EV kit) demonstrates the MAX25069/MAX25169 IC. The EV kit can be configured to operate in a stand-alone or I²C mode.

The TFT-LCD power section of the EV kit operates from a 2.65 V_DC to 5.5 V_DC supply voltage. The BOOST regulator (HVINP) is configured in bipolar mode from 4.9 V to 10.5 V or in unipolar mode from 11.7 V to 18 V output that provides up to 300 mA. The inverting regulator (NAVDD) generates a negative output that tracks the voltage of the boost converter and provides up to 200 mA. The gate-driver power supplies consist of regulated charge pumps that generate in bipolar mode from 8.4 V to 21 V or in unipolar mode from 12.6 V to 31.5 V (VG_ON) and (VG_OFF) from -4 V to -18 V. They can deliver up to 15 mA each, depending on the AVDD setting.

The HB LED driver section demonstrates a step-up DC/DC pre-regulator followed by six channels of linear current sinks. The step-up pre-regulator switches at 2.2 MHz or 400 kHz and operates as a current-mode controlled regulator capable of providing up to 900 mA for the current sinks. Each LED channel can operate up to 36 V and provides up to 150 mA.

The LED driver portion of the EV kit operates from a DC supply voltage of 3 V up to the high-brightness (HB) LED string-forward voltage. The EV kit also demonstrates the IC’s other features, such as adjustable output voltage, extensive diagnostics to fulfill ASIL-B safety level, thermal shutdown, phase-shifted pulse-width modulation (PWM) dimming, and more.

Dimming can be performed externally using a PWM signal applied to the DIM pad or internally by programming the desired dimming frequency and individual duty cycle through I²C. The hybrid dimming feature can be enabled through a register bit to reduce EMI.

The MAX25169EVKIT# EV kit provides an I²C interface that can operate in conjunction with the PICO Board MAX32625 or a third party I²C primary devices such as a general-purpose microcontroller. It also includes Windows®-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the IC.