The CAT4238 is a DC/DC step-up converter from Catalyst Semiconductor that provides an accurate constant current ideal for driving LEDs. It features high efficiency, low quiescent current, adjustable output current, low noise, soft start, etc.
The CAT4238 is a 1 MHz fixed‑frequency, low‑noise boost converter that provides a constant current for up to ten series LEDs. It features up to 87 % efficiency, a low quiescent ground current of 0.6 mA, and built‑in protections such as UVLO at 1.9 V and over‑voltage shutdown at 40 V.
Typical applications include battery‑powered handheld devices, portable media players, GPS navigation systems, and other space‑critical products. The device is supplied in a thin SOT‑23‑5 package and can be ordered with various lead finishes and reel configurations.
| Efficiency | Up to 87 % |
|---|---|
| Input Voltage Range | 2.8 V – 5.5 V |
| Switching Frequency | 1 MHz |
| Quiescent Current | 0.6 mA |
| Undervoltage Lockout (UVLO) | 1.9 V |
| Over‑voltage Detection Threshold | 40 V |
| Maximum LED Current | 40 mA per LED |
The device operates at a fixed switching frequency of 1 MHz.
LED current is set by the external resistor R1 using the formula I_LED = 0.3 V / R1.