Undervoltage and overvoltage lockouts set the driver’s input operating voltage range, while the programmable duty cycle sets the output voltage which turns ratio of the driver. The switching frequency is adjustable from 50kHz to 1MHz and can be synchronised to an external clock. During shutdown, supply current is reduced to less than 1µA. To provide an adjustable soft-start capability, a user-defined RC time constant limits the inrush current at start-up. The driver also features an onboard cross-conduction prevention circuit which increases reliability.
Available in MSOP-10 and 3x3mm DFN-10 packages, the LT3999 E- and I-grade versions operate from a -40 to +125°C junction temperature. The H grade operates from a -40 to +150°C junction temperature, while the MP grade operates from a -55 to +150°C junction temperature. For the E-grade, which is sold in 1,000-piece quantities, prices start at $2.75 each.