Dual Boost Plus Inverting DC/DC Converter for CCD/LCD Applications

Additionally, its second 400mA boost channel generates either a constant current to a string of up to six 20mA white LEDs for LCD backlighting, or a constant voltage to bias an OLED display. Its input voltage range of 2.5V to 6V enables it to be powered from Li-Ion to multiple cell Alkaline/NiMH batteries. Switching at a constant 1MHz, the LT3587 uses tiny, low profile capacitors and inductors and generates low noise outputs that are easy to filter. Output voltages can be set with only one resistor per channel, reducing external component count. Packaged in a 3mm x 3mm QFN, the entire solution has less than a 1mm profile and occupies just 50mm2.

The LT3587 uses an intelligent soft-start circuit that allows for the sequential powering of the Boost1 output, followed by the Inverting output with a single capacitor. Internal sequencing circuitry also disables the inverter until the Boost1 output has reached 87% of its final value, optimizing system reliability.