Synchronous step-down switch regulator controller

The LTC1775 is a synchronous step-down switch regulator controller that uses few external components to drive an external n-channel power mosfet. Current mode control using MOSFET VDS sensing eliminates the need for sensing resistance and improves efficiency. Much like LTC1625

Typical application

The LTC1775 has twice the maximum induced voltage for high-current applications. The frequency of the nominal 150kHz internal oscillator can be synchronized to the external clock in a frequency range of 1.5:1. Burst ModeTM operation at low load current reduces switching losses and low drop-off operation extends the operating time of the battery powered system.

Packaging information

When the main output load is light, the forced continuous mode control pin can assist secondary winding regulation by disabling burst mode operation. Failure protection is provided by a return current limiter and an output overvoltage comparator. External capacitors connected to the RUN/SS pins provide soft startup capability for power sequencing. The wide power range allows input from 4V (4.3V for the LTC1775I) to 36V and output from 1.19V to VIN.

Functional block diagram