Low-noise low-ripple buck converter with integrated ferrite-bead filter compensation

The Texas Instruments TPS6291x devices are a family of high-efficiency, low noise, and low ripple current mode synchronous buck converters. The devices are intended for noise sensitive applications that normally use an LDO for post regulation such as high-speed ADCs, clock and jitter cleaner, serialiser, de-serialiser, and radar applications.

To decrease the output voltage ripple, the device loop compensation is created to operate with an optional second-stage ferrite bead L-C filter. Low-frequency noise levels, similar to a low-noise LDO, are further achieved by filtering the internal voltage reference with a capacitor connected to the NR/SS pin. Combined, these features provide for an output voltage ripple below 10µVRMS.

The device operates at a fixed switching frequency of 2.2MHz, 1.4MHz, or 1MHz, and can be synchronised to an external clock. An optional spread spectrum modulation scheme spreads the DC-DC switching frequency over a wider span, which lowers the mixing spurs.