Sixty-Volt, Current Mode Synchronous Step-Down Controller
Linear Technology’s LTC3812-5 high input voltage synchronous step-down switching regulator controller directly steps down voltages from 60V to output voltages ranging from 0.8V to 93 percent of VIN. Using a single inductor, the device employs a constant on-time valley current mode control architecture to provide very low duty cycles and fast transient response with accurate cycle-by-cycle current limit without requiring a sense resistor. The LTC3812-5's onboard 1-ohm gate drivers minimize switching transient losses associated with driving MOSFETs at high frequency and high voltage. The switching frequency is selectable from 100 kHz to 1 MHz. The controller can be configured for pulse skipping operation to maintain high efficiency at light loads. Its 0.8V reference has ±0.75 percent accuracy over the operating temperature range of -40°C to +85°C. The programmable soft-start allows users to adjust the start-up time. Integrated bias control generates gate drive power from the input supply during start-up with the addition of a small external SOT23 MOSFET. Additional features include a power good signal, shutdown, undervoltage lockout and output overvoltage protection. Pricing for 1,000-piece quantities begin at $3.25 each.