This product is a PFM inductive boost converter designed for driving 2, 3 or 4 series connected white LEDs from a Li-Ion cell and up to 8 LEDs from a 5V supply. It operates from an input supply of between 2.5V and 5.5V and provides an adjustable output current of up to 50mA. The ZXLD1937 includes the output switch and peak current sense resistor, and can operate with a maximum output voltage of 28V. Typical quiescent current is 60μA and a shutdown function is provided to reduce this current to less than 500nA in the 'off' state.
The ZXLD1937 is a PFM inductive boost converter designed for driving 2‑4 series‑connected white LEDs from a Li‑ion cell or a 5 V supply. It operates from 2.5 V to 5.5 V input and provides an adjustable output current up to 50 mA, with internal PWM filtering for flicker‑free dimming. The device includes an internal switch, peak‑current sense resistor and a shutdown function that reduces quiescent current to less than 500 nA.
Typical applications include mobile phones, digital cameras, PDAs, LCD modules and other portable devices. Output current is set by a resistor on the feedback pin, and can be further reduced with a PWM signal on the EN pin using either true analog (filtered) dimming or gated dimming modes.
| Input voltage range | 2.5 V – 5.5 V |
|---|---|
| Maximum output current | 50 mA |
| Quiescent current (typical) | 60 µA |
| Shutdown current | < 500 nA |
| Switching frequency (max) | 1 MHz |
| Efficiency (typical) | 80 % |
| Maximum output voltage | 28 V |
| Power dissipation | 300 mW |
| Operating temperature range | -40 °C to 85 °C |
| Storage temperature range | -55 °C to 150 °C |
| Maximum junction temperature | 125 °C |
| Package | TSOT23‑5, 1 mm max height |
The device can deliver up to 50 mA of LED current.
LED current is programmed by a resistor on the FB pin; I_LED = Vref / R1 with Vref = 100 mV.
It operates from 2.5 V to 5.5 V input.