Boost LED driver for multi-string backlight
The LP5520TL/NOPB: Three independent outputs, each rated for 60 mA, mean the part can drive three parallel LED strings with individual current control — useful for a display backlight where the red, green, and blue channels need separate brightness settings. PWM dimming on the control input lets a host processor or application processor set the LED brightness by modulating the duty cycle, avoiding the colour shift that analog current dimming can cause.
Switching frequency and external component sizing
The LP5520TL/NOPB operates at two internal oscillator frequencies — 1.22 kHz and 19.52 kHz — which set the switching rate of the boost converter. The lower frequency favours efficiency at light loads; the higher frequency shrinks the inductor and output capacitor values at the cost of slightly higher switching losses. Because the part integrates the switching transistor (internal switch = yes), the external BOM stays compact: an inductor, a Schottky diode, and a few ceramic capacitors are all that is needed to complete the boost stage.
25-bump uSMD — board-level integration
Housed in a 25-bump wafer-level chip-scale package (25-WFBGA, also designated 25-uSMD), the LP5520TL/NOPB occupies roughly the footprint of the silicon die itself — no mould compound overhang. The 0.50 mm ball pitch demands a PCB with fine trace/space capability and a solder-mask-defined pad layout. Surface-mount assembly with a standard lead-free reflow profile works, but the uSMD package is moisture-sensitive — the floor life rating (MSL) should be verified from the TI packaging label before the reel is opened.
Temperature grade and operating environment
Rated for -30°C to +85°C ambient, the LP5520TL/NOPB covers the industrial temperature band — suitable for outdoor-rated displays, automotive cabin backlighting (not engine-bay), and portable equipment that sees freezing storage.