National PowerWise buck controllers hit 85% peak efficiency
12/22/2008 7:57 PM EST
Adding to the PowerWise family of DC-DC controllers targeting energy efficiency, National Semiconductor announced four new devices that feature a non-synchronous buck topology and deliver peak energy efficiency of 85%. The LM5085 and LM5088 controllers can operate from inputs as high as 75V while the LM25085 and LM25088 can operate from inputs as high as 42V. All of the products can deliver output voltages as low as 1.2V and load currents over 5A.
The new controllers offer programmable switching frequencies -- allowing the power-supply designer to tradeoff characteristics such as size and energy efficiency. You program the frequency using a single resistor. The products leverage a PWM-based control scheme and also minimize EMI.
The LM5088 and LM25099 are N-channel MOSFET controllers than come in 16-pin TSSOP packages. The products include a frequency dithering feature that varies the switching frequency slightly to reduce EMI peak amplitude by 10dB or more. The devices can also operate as slaves to an external master supply in applications that require multiple tracking supply rails.
The LM5085 and Lm25085 are P-channel MOSFET controllers that suit a tiny footprint via 8-pin SOIC and LLP packages. The designs use a constant-on-time control scheme that provides fast transient response and requires no loop compensation. An integrated P-channel MOSFET minimizes the need for external components and enables 100% duty cycle operation.
The four new products range in price from $0.85 to $1.60 (1000). Get more information from the following web pages.