Switching Regulator Suits Cold-Crank Conditions
Linear Technology has announced the LT3694, a 2.6A, 36V step-down switching regulator that is suitable for the load-dump and cold-crank conditions found in automotive applications. Featuring dual linear controllers, the LT3694 operates from a VIN range of 4 to 36V with transient protection to 70V and is packaged in a 4 x 5mm QFN or TSSOP-20E. Its internal 3.5A switch can deliver up to 2.6A of continuous output current at voltages as low as 0.75V.
Its switching frequency is user-programmable from 250kHz to 2.5MHz, enabling the designer to optimise 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 4 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 utilises 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 high 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 synchronisation capability. The LT3694-1 version is available if a clock output signal is required to synchronise other external devices.
Its switching frequency is user-programmable from 250kHz to 2.5MHz, enabling the designer to optimise 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 4 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 utilises 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 high 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 synchronisation capability. The LT3694-1 version is available if a clock output signal is required to synchronise other external devices.
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