The LT3598 is a fixed frequency step-up DC/DC converter designed to drive up to six strings of LEDs at an output voltage up to 44V. LED dimming can be achieved with analog dimming on the CTRL pin, and with pulse width modulation dimming on the PWM pin. The LT3598 accurately regulates LED current even when the input voltage is higher than the LED output voltage. The switching frequency is programmable from 200kHz to 2.5MHz through an external resistor. Additional features include programmable overvoltage protection, switching frequency synchronization to an external clock, LED current derating based on junction temperature and/or LED temperature, LED string disable control, OPENLED alert pin and output voltage limiting when all LED strings are disconnected. The LT3598 is available in a thermally enhanced 24-pin (4mm × 4mm) QFN package.
The LT3598 LED driver provides up to 30 mA per string with 1.5 % current matching across up to six LED strings. It features a wide input range, programmable switching frequency, and built‑in over‑voltage and open‑LED protection.
The device is supplied in a 24‑lead 4 mm × 4 mm QFN package. Pin functions include LED string outputs, control pins (CTRL, PWM, SYNC), feedback and protection pins (FB, OPENLED), and a shutdown pin. Detailed electrical characteristics, typical performance curves, and a block diagram are included.
| Minimum Operating Voltage | 3.2 V |
|---|---|
| Maximum Operating Voltage | 30 V |
| Output Voltage | Up to 44 V |
| Switching Frequency | 200 kHz – 2.5 MHz (adjustable) |
| LED String Current | 20 mA |
The device operates from a minimum of 3.2 V up to a maximum of 30 V.
Each LED string can be driven up to 20 mA.
The switching frequency is programmable via an external resistor and can be set between 200 kHz and 2.5 MHz.
Over‑voltage protection is provided on the FB pin, which uses a 1.230 V reference voltage.