Step-down controller delivers very low duty cycles

Linear Technology Corp. claims that its LTC3810 high input voltage synchronous step-down switching regulator controller can directly step down voltages from 100V to output voltages ranging from 0.8V to 93 percent of Vin.

This single inductor design eliminates the need for a transformer, said Linear Tech. The device employs a constant on-time valley current mode control architecture to deliver very low duty cycles and extremely fast transient response with accurate cycle-by-cycle current limit without requiring a sense resistor. LTC3810's strong onboard 1Ω gate drivers minimize switching transient losses associated with driving MOSFETs at high frequency and high voltage. To optimize the size of inductors and capacitors, the switching frequency is selectable from 100kHz to 1MHz or can be synchronized to an external source over the same range.

The LTC3810 can be configured for pulse skipping operation to maintain high efficiency at light loads. Its 0.8 volt reference has ?0.75% accuracy over the operating temperature range of -40?C to +85?C. The adjustable soft-start guarantees safe start-up by eliminating turn on overshoot, and the device has a tracking feature to control the output voltage during power up. Applications include 48V power conversion in telecom and basestation power supplies, networking equipment as well as automotive, industrial and avionics systems susceptible to high voltage surges.

The LTC3810 is offered in a 28-lead SSOP package. Pricing for 1,000-piece quantities begin at $3.50 each.