Exploiting its high-voltage analog-bipolar-CMOS-DMOS process (ABCD150-HV), National Semiconductor has created the highly integrated LM5000 power IC line.
One of its first members is the LM5030. This current-mode pulse-width-modulation (PWM) controller combines all of the features needed to implement push-pull and half-bridge power topologies in a thermally enhanced 4- by 4-mm chip-scale package, the LLP-10, or in a 10-pin MSOP.
The LM5030's 15- to 100-V startup regulator eliminates the need for an external regulator built with discretes. This controller targets communications equipment such as central office switches, DSL access multiplexers, high-availability systems, and 48-V distributed power systems.
Other features further simplify power designs. Current-mode control with internal slope compensation simplifies compensation requirements and ensures rejection of line transients. The controller's oscillator can be programmed at frequencies of 100 to 600 kHz using just a single resistor. This eliminates a frequency-programming capacitor and limits the size of external passives with high-frequency switching. The oscillator permits external synchronization, too.
With its two 2-A peak gate drivers, the controller can implement power converters with greater than 150 W of output. A fixed output driver deadtime of 150 ns prevents cross conduction of external MOSFETs as well as transformer saturation. Other functions include dual-mode current-sense limiting, user-programmable soft start, a high-gain-bandwidth error amplifier, and thermal shutdown. Pricing for the LM5030 is $1.85 each per 1000.
Another member of the LM5000 family, the LM5000 chip, is a fully integrated, current-mode PWM regulator in a 16-pin TSSOP or 14-pin LLP. Targeting telecom, automotive, networking, and other applications, it's optimized for use in flyback and boost circuits. Able to generate a high-voltage output with high efficiency, the LM5000 may also be used to build a low-cost auxiliary supply with a low-voltage output (see the figure).
The chip integrates a 3.1- to 40-V startup bias regulator and an 80-V 180-mΩ power MOSFET with a 2-A peak current limit. The IC operates at user-selectable frequencies up to 1.25 MHz. Pricing is $2 each per 1000.