LM2557x and LM557x High Performance Simple Switcher® Series
National Semiconductor's LM557x and LM2557x line of SIMPLE SWITCHER buck regulators feature all of the functions necessary to implement an efficient, high-voltage buck regulator design using minimal external components. The new regulators operate with an input voltage range up to 75V and deliver up to 3A of continuous output current. The patented emulated-current-mode architecture provides superior load transient response in low duty cycle applications that are not addressable by traditional current mode control. Operating frequency is adjustable from 50 kHz to 1 MHz, providing industry-leading dynamic range. To reduce EMI, a frequency synchronization pin allows multiple ICs from the series to self-synchronize or to synchronize to an external clock. The new regulators guarantee robustness with cycle-by-cycle current limit, short-circuit protection and thermal shut-down.
Features
Wide input voltage ranges from 6V to 75V
Emulated current mode architecture offers superior performance:
Excellent transient response
Ultra-short duty cycle
Reduced noise sensitivity
Adjustable switching frequencies between 50 kHz and 1 MHz
Up to 3A of output current
Self synchronizes when connected to other regulators or an external clock
Adjustable soft-start
Full support with industry leading Webench design tool
Available in TSSOP or thermally enhanced ETSSOP packaging
National Semiconductor's LM557x and LM2557x line of SIMPLE SWITCHER buck regulators feature all of the functions necessary to implement an efficient, high-voltage buck regulator design using minimal external components. The new regulators operate with an input voltage range up to 75V and deliver up to 3A of continuous output current. The patented emulated-current-mode architecture provides superior load transient response in low duty cycle applications that are not addressable by traditional current mode control. Operating frequency is adjustable from 50 kHz to 1 MHz, providing industry-leading dynamic range. To reduce EMI, a frequency synchronization pin allows multiple ICs from the series to self-synchronize or to synchronize to an external clock. The new regulators guarantee robustness with cycle-by-cycle current limit, short-circuit protection and thermal shut-down.
