MAX25169 150 mA Backlight Driver
Analog Devices' MAX25169 has remote temperature sensing with programmable warning and shutdown thresholds
Image of Analog Devices' MAX25169 150 mA Backlight DriverADI'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 VDC to 5.5 VDC 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 (VGON) and (VGOFF) 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.
Features
4-output TFT-LCD bias power
2.65 V to 5.5 V input for the TFT-LCD section
Integrated 420 kHz or 2.1 MHz boost and buckboost converters
Positive and negative 15 mA gate voltage regulators with adjustable output voltage (tripler/inverting doubler)
Flexible sequencing
Undervoltage detection on all outputs
Low-quiescent-current standby mode
6-channel, 36 V LED backlight driver
NGATE control for external nMOSFET series switch
Programmable nMOSFET current limit
Up to 150 mA current per channel
4.5 V to 36 V input voltage range, 3 V operation after startup
Integrated boost/SEPIC controller (400 kHz to 2.2 MHz with synchronization)
Dimming ratio 16,667:1 at 200 Hz
Adaptive voltage optimization to reduce power dissipation in LED current sinks
Open-string, shorted-LED, and short-to-GND diagnostics
Low EMI
Phase-shift dimming of LED strings
Spread spectrum on LED driver and TFT outputs
Selectable switching frequency
I2C interface for control and diagnostics
Fault indication through the FLTB pin and I2C
Nonvolatile configuration memory
Overload and thermal protection
ASIL B compliant
-40°C to +125°C ambient temperature operation
7 mm x 7 mm, 48-pin TQFN package with exposed pad
AEC-Q100 Grade 1
Applications
High availability server backplane systems
12 V/24 V/48 V/54 V distributed power systems
Industrial