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Send til en ven   Udskriv17/2 2012 kl. 11:58
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Stepdown regulator kan justeres ned til 0V med bare én modstand

Linear Technology lancerer synkron rail-to-rail step-down regulator, der ved brug af bare én modstand kan programmeres til at levere 1,5A ved spændinger fra 0V til 15V (in english).

Modern medical, industrial and battery-powered applications continue to require increasingly complex electronic power systems. With the proliferation of low voltage microprocessors and microcontrollers power conversion ICs are required to deliver lower and lower output voltages without compromising efficiency, transient response or output voltage accuracy.

For example, some FPGAs and DSPs currently require output voltages as low as 0.6V from 12V inputs. Additionally, these applications require high efficiency, very accurate output accuracy (+1% over temperature) and very fast transient response to load steps.
As the output voltage can vary anywhere from slightly below the input voltage down to a few hundred millivolts, it is important that the loop dynamics are independent of the output voltage. Finally, high switching frequencies, even with duty cycles as low as 5%, are required to keep switching noise out of noise sensitive frequency bands such as xDSL bands

and keep external components as small as possible, minimizing the solution footprint. 

Linear Technology addresses these challenges and applications with the new LTC3600, a 1.5A, high efficiency, synchronous buck regulator that can be easily paralleled for higher current applications and is adjustable down to 0V with a single resistor.

This new switching regulator architecture uses a 50µA current reference, combined with a single resistor to set the output voltage. This unique design enables easy current sharing between multiple regulators, setting the output voltage for all of the regulators with a single external resistor.

The LTC3600 delivers high performance without any compromises. The device’s wide input voltage capability from 4V to 15V makes it ideal for dual-cell Li-Ion applications, as well as fixed 5V and 12V intermediate bus systems and synchronous rectification delivers efficiencies as high as 96%. 

The LTC3600’s novel design allows dynamic adjustment of output voltage from 0V to VIN-0.5V, offering virtually rail-to-rail performance. The device’s ability to provide zero output enables it to power down individual rails in the system as needed. Its on-chip trimmed reference achieves accuracy of ±1%. Furthermore, output regulation and transient response are independent of output voltage.

Output voltage tracking or soft start is easily programmed via the ISET pin for applications that require power sequencing. The LTC3600’s wide VIN & VOUT capability, tight line and load regulation, high efficiency, low external parts count and parallel capability make it ideal for modern multirail systems.

The LTC3600’s combination of a 3mm x 3mm DFN or a thermally enhanced MSOP-12 package and its 200kHz to 4MHz switching capability enable use of tiny, low cost capacitors and inductors, offering a very compact solution footprint for multirail applications. Additional features include a power good voltage monitor, external synchronization capability and thermal protection.

The LTC3600EDD is available in a 3mm x 3mm DFN-12, and the LTC3600EMSE is offered in a 12-lead, thermally enhanced MSOP package. Industrial grade versions, the LTC3600IDD and LTC3600IMSE, are guaranteed to operate over the -40°C to 125°C operating junction temperature range.
www.linear.com/product/LTC3600

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