National Semiconductor Corp. has expanded its family of high-voltage buck regulators with the introduction of the LM5005. This high-frequency buck regulator steps down an input voltage from 7 V to 75 V to produce a regulated 2.5-A power supply, adjustable from 1.225 V to 65 V. Reliable and compact, the LM5005 is optimized for 48-V telecom, automotive and industrial power supply applications.
The LM5005 high-voltage switching regulator integrates a 75-V N-channel MOSFET and employs a proprietary scheme that uses emulated, current-mode pulse-width modulation (PWM) to produce a 2.5-A step-down regulator with minimal external components. This proprietary control method generates an internal emulated inductor current ramp, which significantly reduces the noise sensitivity of the controller. This allows the LM5005 to reliably control very small duty cycles so designers can take full advantage of the LM5005’s wide 75-V input and 500-kHz frequency capabilities. In addition, current-mode control provides inherent line voltage feed-forward and simplified loop compensation. The programmable operating frequency can range from 50 kHz to 500 kHz. A novel, bidirectional oscillator synchronization pin allows multiple LM5005 regulators to self-synchronize or switch synchronously with an external clock. Additional protection features include current limit, thermal shutdown and remote shutdown capability.
The device is available in the TSSOP-20 package, featuring an exposed mounting pad to enhance the package’s thermal dissipation. Unit pricing is $3.25 in 1000-unit quantities.