# Coupled inductors designed for Volterra chipsets

San Diego, Calif. — Pulse, a Technitrol Company, said it has introduced the industry's first family of coupled inductors for non-isolated step-down DC/DC voltage regulators. The PA131xNL multi-phase coupled inductors are manufactured under a license agreement with Volterra to support its VT1165M and VT1115M chipsets.

The PA131xNL family of off-the-shelf, surface-mount, RoHS-compliant inductors features 2, 3, 4, or 5 phases magnetically coupled together in a single part. Each phase has an equivalent transient inductance (Lk) of 50 nanoHenries (nH) and a magnetizing inductance (Lm) greater than 250 nH. Each phase is rated for 40 amps (A) and has a direct current resistance (DCR) of 0.5 milliohms maximum.

In addition, these parts can accommodate a 5A current imbalance between phases, which ensures operation in less-than-ideal conditions, said the company. When used with Volterra's chipsets, which implement the coupled inductor topology, the inductors are said to provide lower current ripple per phase, improved transient response and higher efficiency. As a result of the lower transient inductance, fewer bulk capacitors are needed to support high-transient-load applications, thus reducing cost, according to the company.

In a non-coupled multi-phase DC/DC converter, each phase has an independent inductor. Though the value of the inductor must be reduced to improve transient response, which increases current ripple per phase and decreases efficiency, this is not the case with a coupled inductor topology.

The company said in a coupled inductor topology, all of the inductors are integrated on the same magnetic core and the interaction of the magnetic fields from each phase enables the use of a lower equivalent inductance for faster transient response without increasing the current ripple per phase. The reduction in ripple current compared to a non-coupled solution is approximately 50% for a 2-phase system, 66% for 3-phase, 73% for 4-phase, and 77% for a 5-phase system.

Package dimensions of the PA131xNL parts are 18.3 x 9.0 x 5.2 mm for PA1312NL, 27.3 x 9.0 x 5.2 mm for PA1313NL, 36.6 x 9.0 x 5. 2 mm for PA1314NL, and 42.7 x 9.0 x 5.2 mm for PA1315NL. Click the link for the PA131xNL datasheet.

Samples are available for approved Volterra customers using the Volterra chipset. Volume production is available. Packaged on tape-and-reel and in trays, pricing is $0.45/piece for the PA1312NL, $0.60/piece for the PA1313NL, $0.75/piece for the PA1314NL, and $0.90/piece for the PA1315NL, in quantities of 50,000. Pricing may vary due to order configuration and shipping destination.

**Pulse**, 1-858-674-8100, www.pulseeng.com