Its switching frequency is user-programmable from 250kHz to 2.5MHz, enabling the designer to optimize efficiency while avoiding critical noise-sensitive frequency bands. Each integrated LDO controller has an accurate programmable current limit up to 1A to provide an additional level of reliability. Combined with NPN transistors, they can be used to offer dual low noise outputs in addition to the primary channel. Although the LDO controllers can be powered by independent inputs, powering them from the primary switching output ensures both high efficiency and low noise. The combination of its 4mm x 5mm QFN package (or thermally enhanced TSSOP-20E) and high switching frequency, which keeps external capacitors and inductors small, provides a compact, thermally efficient footprint.
The LT3694’s main switcher utilizes a high efficiency 3.5A switch, with the necessary oscillator, control, logic circuitry and LDO controllers integrated into a single die. Special design techniques enable high efficiency over a wide input voltage range and its current mode topology enables fast transient response and excellent loop stability. A diode current limit pin offers an additional level of overload protection. Other features include a power good flag, independent tracking/soft-start pins and programmable undervoltage lockout.
The LT3694 also provides synchronization capability. The LT3694-1 version is available if a clock output signal is required to synchronize other external devices.