LM5118/LM5118Q,pdf datasheet (

The LM5118 wide voltage range Buck-Boost switching regulator
controller features all of the functions necessary to implement
a high performance, cost efficient Buck-Boost
regulator using a minimum of external components. The
Buck-Boost topology maintains output voltage regulation
when the input voltage is either less than or greater than the
output voltage making it especially suitable for automotive
applications. The LM5118 operates as a buck regulator while
the input voltage is sufficiently greater than the regulated output
voltage and gradually transitions to the buck-boost mode
as the input voltage approaches the output. This dual mode
approach maintains regulation over a wide range of input
voltages with optimal conversion efficiency in the buck mode
and a glitch-free output during mode transitions. This easy to
use controller includes drivers for the high side buck MOSFET
and the low side boost MOSFET. The regulator’s control
method is based upon current mode control utilizing an emulated
current ramp. Emulated current mode control reduces
noise sensitivity of the pulse-width modulation circuit, allowing
reliable control of the very small duty cycles necessary in
high input voltage applications. Additional protection features
include current limit, thermal shutdown and an enable input.
The device is available in a power enhanced TSSOP-20
package featuring an exposed die attach pad to aid thermal
dissipation.