The LM2678 series of regulators are monolithic integrated circuits which provide all of
the active functions for a step-down (buck) switching regulator capable of driving up to 5-A loads
with excellent line and load regulation characteristics. High efficiency (>90%) is obtained
through the use of a low ON-resistance DMOS power switch. The series consists of fixed output
voltages of 3.3 V, 5 V, and 12 V and an adjustable output version.
The SIMPLE SWITCHER® concept provides
for a complete design using a minimum number of external components. A high fixed frequency
oscillator (260 kHz) allows the use of physically smaller sized components. A family of standard
inductors for use with the LM2678 are available from several manufacturers to greatly simplify the
design process.
The LM2678 series also has built-in thermal shutdown, current limiting, and an ON/OFF
control input that can power down the regulator to a low 50-µA quiescent current standby condition.
The output voltage is ensured to a ±2% tolerance. The clock frequency is controlled to within a
±11% tolerance.
