The TPS61181A IC provides highly integrated solutions for media size LCD backlighting. These devices have a built-in high efficiency boost regulator with integrated 1.5A/40V power MOSFET. The six current sink regulators provide high precision current regulation and matching. In total, the device can support up to 60 WLEDs. In addition, the boost output automatically adjusts its voltage to the WLED forward voltage to improve efficiency.
The devices support pulse width modulation (PWM) brightness dimming. During dimming, the WLED current is turned on/off at the duty cycle and frequency determined by the PWM signal input to the DCRTL pin. One potential issue of PWM dimming is audible noise from the output ceramic capacitors. The TPS61181A is designed to minimize this output AC ripple across a wide dimming duty cycle and frequency range and therefore, reduce this audible noise.
The TPS61181A provides a driver output for an external PFET connected between the input and inductor. During short circuit or over-current conditions, the IC turns off the external PFET and disconnects the battery from the WLEDs. The PFET is also turned off during IC shutdown (thereby giving "true" shutdown) to prevent any leakage current from the battery. The device also integrates over-voltage protection, soft-start and thermal shutdown.
The TPS61181A has a built-in linear regulator for the IC supply. The devices are in a 3×3 mm QFN package.