Regulator avoids critical noise-sensitive frequency bands

28th October 2014
Siobhan O'Gorman

Featuring a synchronous rectification topology, the LT8609, a 2A, 42V input synchronous step-down switching regulator, has been released by Linear Technology. Avoiding critical noise-sensitive frequency bands, such as AM radio, the topology delivers 93% efficiency while switching at 2MHz.

In no-load standby conditions, Burst Mode operation keeps quiescent current under 2.5µA, making the regulator suitable for always-on systems. With a 3.0 to 42V input voltage range, the device is suitable for automotive applications which need to regulate through cold-crank and stop-start scenarios with input voltages as low as 3.0V and load dump transients greater than 40V. Up to 2A of continuous output current with peak load currents of 3A are delivered by the internal 3.5A switches.

Enabling efficient operation in scenarios such as automotive cold-crank, the LT8609 maintains a minimum dropout voltage of only 200mV at 1A under all conditions. To minimise noise in automotive and industrial environments, spread spectrum frequency modulation and special design techniques offer low-EMI operation. 2MHz constant frequency switching from a 16V input to a 1.5V output is enabled by a fast minimum on-time of only 45ns. The device’s 10-lead thermally enhanced MSOP package combined with it’s high switching frequency allows for small external inductors and capacitors and, therefore, a compact, thermally efficient footprint.

The LT8609, which integrates a boost diode, oscillator, control and logic circuitry into a single die, utilises internal top and bottom high efficiency power switches. While keeping output ripple below 10mVpk-pk, low ripple Burst Mode operation maintains high efficiency at low output currents. Fast transient response and loop stability is enabled by the device’s current-mode topology. Internal compensation, a power good flag, output soft start/tracking and thermal protection are also provided with the regulator.

The LT8609EMSE is available now, in 1,000 unit quantities for $2.50 each. Linear Technology also offers an industrial temperature version of the regulator. The LT8609IMSE, which is tested and guaranteed to operate from a junction temperature range of -40 to 125°C, is sold in 1,000 unit quantities at $2.75 each.

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