Low-IQ synchronous buck controller for 12 V and 24 V rails
The LTC7803JMSE#PBF is a low quiescent current synchronous step-down (buck) controller from Analog Devices, designed for converting 4.5 V to 40 V input rails down to a regulated positive output. It drives external N-channel MOSFETs in a single-phase synchronous topology, which means the low-side FET replaces the freewheeling diode for higher efficiency across the load range. The controller integrates clock synchronization, frequency control, and phase control, making it suitable for multi-rail systems where switching harmonics must be aligned or spread.
100% duty cycle — what it means for dropout
The LTC7803JMSE#PBF can operate at 100% duty cycle, meaning the high-side FET can stay on continuously. This keeps the output in regulation when the input voltage sags close to the output target.
Switching frequency: 100 kHz to 3 MHz — inductor and EMI trade-offs
The switching frequency is programmable from 100 kHz to 3 MHz via the frequency control pin. Lower frequencies reduce switching losses and simplify layout but require larger inductors.
Temperature grade and environment
Rated for a junction temperature range of -40°C to 150°C, the LTC7803JMSE#PBF is specified for automotive under-hood, industrial motor drives, and outdoor telecom equipment.
Package and thermal management
Housed in a 16-lead MSOP with exposed pad (16-MSOP-EP), the thermal pad must be soldered to a PCB copper plane to dissipate heat from the internal LDO and gate drivers.