National touts first emulated current-mode controller with ultra-wide operating range

Santa Clara, Calif.—National Semiconductor's LM5118 buck-boost regulator uses emulated current-mode control to ensure reliable control of very small duty-cycles over a best-in-class 3-to-75 volts input for automotive, telecommunications and battery-powered systems. Emulated current-mode control, used in place of traditional current-mode topologies, greatly minimizes the effect of PWM switching noise and provides significantly better line and transient response, according to the company. The emulated signal is the sum of an emulation ramp current and the sampled diode current just before switching occurs.

The chip's two-switch configuration lends to its ultra-wide input voltage range. A car's battery voltage can fall momentarily to 4 volts during cold-crank conditions if the battery is weak. The LM5118, part of the company's PowerWise family, will operate at these lower voltages, retaining power to the auto's dashboard display, anti-lock braking and fuel injection control systems, and the multitude of the car's microcontrollers.

The LM5118 features programmable switching frequency up to 500 kHz, ultra-low shutdown current and peak efficiency of 95 percent. The LM5118's buck-boost topology maintains a glitch-free output during mode transitions. The chip includes drivers for the high-side buck MOSFET and the low-side boost MOSFET. Output current (from external MOSFETs) is up to 10 amps. Additional protection features include current limit, thermal shutdown, and an enable input. The LM5118 is offered in a 20-pin thermally enhanced TSSOP package.

Datasheet : Click here.

Pricing :The LM5118 is priced at $2.92 each in 1,000-unit quantities.

National Semiconductor , 1-800-272-9959,

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