Controllers handle complex power requirements

The new LM274x family of high-speed synchronous switching regulator controllers run from a 1 to 16V input power rail and provide output voltages down to 0.6V.

The new LM274x family of high-speed synchronous switching regulator controllers run from a 1 to 16V input power rail and provide output voltages down to 0.6V.

Applications for the LM274x family include set-top boxes, cable modems, rack-mounted equipment, networking products and any other system that employs a DSP, FPGA, ASIC or processor that requires supply voltages of 1.8V or lower.

"The LM274x family from National Semiconductor is addressing the power requirements of a growing market segment of complex electronics that use DSPs, FPGAs and ASICs, and rely on efficient power management solutions to enable smaller end products", said Paul Greenland, Marketing Director for National Semiconductor's Power Management Group.

"This new family of controllers is the next step in National Semiconductor's portfolio of industry-leading power management solutions".

The LM2742, a high-speed, synchronous switching regulator controller, is capable of controlling currents of 0.7 to 20A with up to 95% conversion efficiency.

Power up and down sequencing is achieved with the power-good flag, adjustable soft-start and output enable features.

The LM2742 operates from a low-current 5V bias rail and converts from a 1 to 16V power rail.

It uses a fixed-frequency, voltage-mode pulsewidth modulation (PWM) control architecture, and its switching frequency can be adjusted from 50kHz to 2MHz by setting an external resistor.

Current limit is achieved by monitoring the voltage drop across the on-resistance of the conducting low-side MOSFET, with best-in-class 40ns minimum on-time.

The wide range of operating frequencies gives the power supply designer flexibility to fine-tune component size, EMI and efficiency.

The adaptive, nonoverlapping MOSFET gate drivers and high-side bootstrap driver help maximise efficiency without compromising reliability.

This part keeps the low-side MOSFET switched off during shutdown, preventing the discharge of the output filter capacitor.

The LM2743 is a high-speed, N-channel synchronous buck regulator controller with a 2% 0.6V feedback reference voltage.

It uses a fixed-frequency, voltage-mode PWM control architecture that is adjustable from 50kHz to 1MHz through an external resistor.

This wide range of PWM frequencies gives the power supply designer the flexibility to make tradeoffs among component size, EMI and efficiency.

The power MOSFETs can run on a separate 1 to 16V input voltage rail, and the regulator is biased from a 3 to 6V, 2mA rail.

A power-good flag, precision shutdown threshold and soft-start features make power supply tracking and sequencing easy.

The LM2743 also employs current limit, which is achieved by monitoring the voltage drop across the on-resistance of the conducting low-side MOSFET, as well as an output undervoltage and overvoltage flag.

The adaptive, nonoverlapping MOSFET gate drivers help avoid shoot-through currents while maintaining high efficiency.

The high-side and low-side MOSFETs are the N-channel type, and the IC bootstrap structure enhances the high-side MOSFET for the highest efficiency.

The LM2744 has the same feature set as the LM2743 and includes an external reference that the user can connect to an error amplifier for tighter DC output accuracy.

Available today, National's LM2742 is priced at $1.50 each in 1000-off volumes, the LM2743 is priced at $1.30 each in 1000-off volumes and the LM2744 is priced at $1.20 each in 1000-off volumes.

All three products are available in TSSOP-14 packages.

Back to top