Synkron DC/DC konverter honorerer de højeste automotive-krav
Linear Technology lancerer 42V quad synkron step-down DC/DC konverter, der opererer fra 3V til 42V inputs med en effektivitet på til 93 procent (in english).
Modern automotive power management ICs continue to require higher performance. As the power requirements for these applications continues to grow, the available space for power conversion solutions continually shrinks requiring even higher power densities.Furthermore, the required electrical performance criteria of these switching regulators becomes more demanding. Offering four independent outputs in the same solution footprint as many single output devices becomes desirable in many applications.
For example, automotive applications running from the battery bus require a well regulated output voltages form 0.8V to 5V, even as the input voltage can swing from under 4V in a cold crank or stop/start scenario up to 40V in a load dump scenario.
Similarly, high efficiency is of paramount importance as it minimizes thermal design considerations while also maximizing battery run time in hybrids and electric vehicles. For applications such as security, navigation, safety and environmental control which are often required to be always on, minimal quiescent current is critical so as not to drain the battery when the car is parked for long periods of time. 2MHz frequency operation avoids noise in critical frequency bands such as AM radio and keeps external components very small. Finally very robust short-circuit and overvoltage protection ensures overall system reliability.
Linear Technology continues to grow its family of synchronous high voltage step-down regulators by adding a quad output synchronous step-down converter which specifically addresses all of the above stated requirements.
LT8602 is a 42V input capable, high efficiency quad output synchronous monolithic step-down switching regulator. Its quad channel design combines two high voltage 2.5A and 1.5A channels with two lower voltage 1.8A channels to provide four independent outputs, delivering voltages as low as 0.8V.
Its synchronous rectification topology delivers up to 93% efficiency while Burst Mode operation keeps quiescent current under 30µA (all channels) in no-load standby conditions, making it ideal for always-on systems. For noise-sensitive applications, the LT8602 utilizes its pulse-skipping mode to minimize switching noise and meet the CISPR25, Class 5 EMI requirements. Switching frequency can be programmed from 250kHz to 2.2MHz and is synchronizable throughout this range.
The LT8602’s 60ns minimum on-time enables 16VIN to 0.8VOUT step-down conversions while switching at 2MHz, enabling designers to avoid critical noise-sensitive frequency bands such as AM radio, while using a very compact solution footprint. Its 3V to 42V input voltage range makes it ideal for automotive applications that must regulate through cold-crank and stop-start scenarios with minimum input voltages as low as 3V and load dump transients in excess of 40V.
Each channel of the LT8602 maintains a minimum dropout voltage of only 200mV (at 1A) under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Programmable power-on reset and power good indicators for each channel ensure overall system reliability. The LT8602’s 40-lead thermally enhanced 6mm x 6mm QFN package and high switching frequency keep external inductors and capacitors small, providing a compact, thermally efficient footprint.
The LT8602 utilizes quad internal top and bottom high efficiency power switches with the necessary boost diodes, oscillator, control and logic circuitry integrated into a single die. Channel 1 and 3 switch 180° out of phase with channels 2 and 4 to reduce output ripple.
Each channel has a separate input for added design flexibility, but most applications will run the two low voltage channels directly from the two high voltage channels to provide a very simple, high frequency quad output design. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mVP-P.
Unique design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8602’s current-mode topology enables fast transient response and excellent loop stability. Other features include internal compensation, power good flags, output soft-start/tracking, short-circuit and thermal protection.
The LT8602 is available in a thermally enhanced 40-lead 6mm x 6mm QFN package. Three temperature grades are available, with operation from –40°C to 125°C (junction) for the extended E- and industrial I-grades.
