Electronic Design

Power-Supply ICs Reach For Greater Performance

Higher switching frequencies reduce design size while sequencing functions ease power management.

Recently introduced power-supply controllers and low-drop-out (LDO) regulators have raised the performance bar for embedded dc-dc converters.

Linear Technology's LTC3414 is a synchronous buck converter with both high- and low-side MOSFETs on-chip. Its switching frequency is programmable from 300 kHz to 4 MHz. In contrast, comparable existing synchronous buck converters generally switch at frequencies below 1 MHz. The LTC3414's high operating frequency permits the use of smaller external passives, resulting in a complete design footprint that's less than 300 mm2.

Operating from a 2.25- to 5.5-V input, the LTC3414 delivers 4 A at outputs as low as 0.8 V. Efficiency peaks at 95% but is better than 90% over four decades of load current. Units cost $5.95 in 1000-piece quantities. For more, go to www.linear.com.

From Vishay Siliconix, the Si9139 triple-output switching power-supply controller is rated for 50 W output with operation from a 4.5- to 30-V input (see the figure). Housed in a 28-pin SSOP package, the chip integrates two main synchronous step-down controllers rated for up to 6 A each with fixed outputs ranging from 1.5 to 3.3 V. Its third output, a step-up/down controller, has a 500-mA output at an adjustable 1.24 to 20 V. An on-chip 5-V, 30-mA linear regulator provides a fourth output. The chip's two main outputs also supply individual control for power-up sequencing. Pricing in 50,000-piece quantities is $2.50. Go to www.vishay.com for details.

Texas Instruments also picks up the power sequencing torch in the latest versions of its SWIFT family of synchronous buck dc-dc converter ICs. The TPS54x80 features a TRACKIN pin with a multiplexer to implement simultaneous, sequential, or ratiometric sequencing of supply voltages. Further information about the SWIFT family can be found at power.ti.com/sc03065.

In the linear regulator area, the MAX8510/MAX8511/MAX8512 120-mA LDO regulators from Maxim Integrated Products provide high performance in the tiny SC-70 package. With a noise specification of 11 µVRMS, the MAX8510 may qualify for use in RF applications where even the larger SOT-23 packaged regulators may have difficulty. Dropout is just 120 mV at the rated current. A 1-µF ceramic capacitor on the output maintains stability. For more, see www.maxim-ic.com.

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