The ZXSC400 is a voltage mode boost converter in the SOT23-6 package. Its low feedback voltage allows the current in a chain of LEDs to be set and accurately monitored with a single resistor giving minimal losses. Its excellent load and line regulation means that for the full supply range from lithium-ion cells, the LED current will typically change by less than 1%. Using high efficiency Zetex switching transistors with ratings of 20V and higher allow many LEDs to be chained in series for the best LED current matching possible.