Boost regulator for single-LED-string backlights
The LM3519MK-20/NOPB is a fixed-frequency, step-up (boost) DC-DC regulator from Texas Instruments, designed specifically to drive a single series string of white LEDs for backlight applications. It integrates the switching MOSFET internally and delivers a regulated 20 V output at up to 20 mA per channel from a 2.7 V to 5.5 V input supply.
PWM dimming and the 20 V output ceiling
Brightness control is handled through a PWM dimming input, which lets you modulate the LED current without affecting colour temperature — standard practice for display backlights. The 20 V output rail is the maximum compliance voltage for the LED string; if your backlight needs more than that (e.g. six or more white LEDs in series), this part won't support it. For a typical three- or four-LED string at 20 mA, the 20 V ceiling gives about 5 V headroom per LED, which is comfortable for most white LEDs at full brightness.
It will handle outdoor telecom panels, automotive cabin displays, and factory HMI backlights without issue. Not rated for under-hood or engine-bay environments — those would need the 125°C rated LM2703 variant if you need higher temperature tolerance.