The LM274x family of synchronous buck controllers from National Semiconductor offers 1% voltage feedback accuracy across an extended industrial temperature range. The family consists of four controllers—the LM2745, ‘2746, ‘2747, and ‘2748 - each of which is meant to provide precise core regulation. The ICs are also designed to work at higher frequencies.
The controllers feature a 40-ns minimum on-time, making it possible to generate an output of 0.6 V from a 12-V rail at a switching frequency of 1 MHz. In addition, the LM2747 feature set includes pre-bias load start-up capability, soft-start with tracking, a precision enable for sequencing of power rails, and external clock synchronization to reduce interaction with other supplies and sensitive load circuitry.
The LM2746 has the same performance as the LM2747 but does not include the pre-bias load start-up capability or the external clock synchronization feature. The LM2745 has the same feature set as the LM2747, but offers reduced voltage feedback accuracy of 1.5% over the extended temperature range. The LM2748 has the same accuracy as the LM2745, but without an external clock synchronization feature.
Available now, the LM274x family is priced starting at $1.45 in 1000-unit quantities for the LM2746. Samples and evaluation boards for this product family are available.