National Semiconductor LM21212-1/LM21215 buck regulator range

National Semiconductor has introduced a pair of high-current, synchronous buck regulators with what is claimed to be the industry’s highest efficiency at 97%.

The LM21212-1 and LM21215 are suitable for high-performance FPGAs, ASICs and microprocessors used in a variety of low-voltage applications including wireless, networking and optical communications infrastructure.

Members of the PowerWise energy-efficient product family, the regulators feature integrated high-side and low-side FETs, which simplify design and reduce solution size.

The LM21212-1 features an output current up to 12 A with synchronisable switching frequency and the LM21215 provides a resistor-programmable current limit, allowing up to 15 A of continuous output.

Both products provide peak efficiency greater than 97% from a 5 V input to 3.3 V output and greater than 92% efficiency when regulating a 1.2 V output from a 5 V input.

The regulators are monolithic synchronous types. The LM21212-1 is capable of delivering up to 12 A of continuous output with a switching frequency that can be synchronised to an external oscillator between 300 kHz and 1.5 MHz.

The LM21215 features a fixed 500 kHz switching frequency and is capable of delivering up to 15 A.

The regulators are optimised to work over an input voltage range of 2.95 to 5.5 and produce an output voltage down to 0.6. The voltage-mode control loop provides high noise immunity and narrow duty cycle and can be compensated to be stable with any type of output capacitor for maximum flexibility and ease of use.

A programmable overcurrent protection feature allows a user to specify the peak current level. An internal overvoltage protection circuit provides increased system reliability, while a precision enable pin and integrated UVLO allow turn-on of the device to be tightly controlled and sequenced.

Start-up inrush currents are limited by both an internally fixed and externally adjustable soft-start circuit. Both regulators provide a monotonic start-up into a pre-biased load, preventing the devices from sinking current until the internal soft-start ramp exceeds the voltage at the feedback pin.

Fault detection and supply sequencing are also possible with the integrated power-good circuit.