The switching noise generated by dc-dc converters is unacceptable in applications like medical imaging, sonar, and automated test equipment (ATE). Passive filters can be employed to clean up the converters' outputs, but these filters have limitations. To attenuate low frequencies, passive LC filters require large inductors or capacitors. And while less bulky passive filters can attenuate higher frequencies of 100 kHz or more, they still degrade the power supply's transient response.
Vicor's MicroRAM, an output ripple attenuation module, uses both active and passive filtering to attenuate the conducted differential noise generated by a dc-dc converter while improving the converter's load transient response via point-of-load regulation. Offered in a quarter-brick package, the MicroRAM provides greater than 40 dB of attenuation from 60 Hz to 1 MHz for any supply with 3 to 30 V of dc output at up to 20 A. Response time to a 10-A load transient is roughly 1 µs.
Although Vicor already offers a 40-dB ripple attenuation module (RAM), that product was designed only for use with the company's dc-dc converters and comes in a larger (half-brick) package. In contrast, MicroRAM operates with any dc-dc converter. It can be configured for regulation control either by using the source's remote sense or voltage trim. Also, it supports N+1 redundant and parallel operation with an integrated ORing diode function.
The company plans to introduce a quarter-brick version of MicroRAM rated for 30 A and a 1-in.2 SIP model rated for 10 A and 20 dB of attenuation. Eventually the SIP package will be downsized to 10 by 10 mm through the development of an ASIC.
Pricing starts at $37 in OEM quantities with units available from stock.
Vicor, (800) 735-6200; www.vicr.com/products/datasheets/ds_microram.pdf.