MAX25169

The MAX25169 evaluation kit (EV kit) demonstrates the MAX25069/MAX25169 IC, which is a highly integrated power supply plus LED backlight driver for automotive TFT-LCD applications. The EV kit is a fully assembled and tested surface-mount PCB that provides a complete power-management solution for automotive displays. The EV kit demonstrates one current-mode boost converter with sequencing switch (HVINP–AVDD), one current mode inverting regulator (NAVDD), positive and negative gate-voltage controllers (VG_ON), and (VG_OFF), and a boost converter that powers a six-string LED driver.

The EV kit can be configured to operate in a stand-alone mode or an I²C mode.

The TFT-LCD Power Section of the EV kit operates from a 2.65V to 5.5V DC supply voltage. The BOOST regulator (HVINP) is configured in bipolar Mode from 4.9V to 10.5V or in unipolar Mode from 11.7V to 18V output that provides up to 300mA. The inverting regulator (NAVDD) generates a negative output that tracks the voltage of the boost converter and provides up to 200mA. The gate-driver power supplies consist of regulated charge pumps that generate in Bipolar Mode from 8.4V to 21V or in Unipolar Mode from 12.6V to 31.5V (VGON), and (VG_OFF) from -4V to -18V. They can deliver up to 15mA 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 2.2MHz or 400kHz and operates as a current-mode controlled regulator capable of providing up to 900mA for the current sinks. Each LED channel can operate up to 36V and provides up to 150mA.

The LED driver portion of the EV kit operates from a DC supply voltage of 3V 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 aid in fulfilling ASIL-B safety level, thermal shutdown, phase-shifted pulse-widthmodulation (PWM) dimming, etc.

Dimming can be performed either 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 EV kit provides an I²C interface that can operate in conjunction with the PICO BOARD MAX32625 or a thirdparty I²C master such as a general-purpose microcontroller.

The EV kit also includes Windows^®-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the IC.