ACT510x
Rev 1.0, 04-Apr-2018
FUNCTIONAL DESCRIPTION
1. Buck-Boost Structure
The ACT510x is a monolithic buck-boost converter with integrated FETs. Four internal low resistance NMOS switches
minimize the size of the application circuit and reduce power losses to maximize efficiency. Internal high side gate drivers,
which require only the addition of two small external capacitors, further simplify the design process. An advanced switch
control algorithm allows the buck-boost converter to maintain output voltage regulation with input voltages that are above,
below or equal to the input voltage. Transitions between these operating modes are seamless and free of transients and
subharmonic switching.
VIN
VOUT
L
Q1
Q4
Q2
Q3
Figure 3: Diagram for 4-Switches Buck-Boost Converter
Figure 4: Operation Mode and Regions
Figure 3 shows a simplified diagram of how the four power switches are connected to the inductor, VIN, VOUT and GND.
Figure 4 shows the regions of operation for the ACT510x as a function of duty cycle D. The power switches are properly
controlled so the transfer between modes is continuous. When VIN approaches VOUT, the buck-boost region is reached.
Table 1: MOSFET Operation
MODE
Q1
BUCK
SWITCHING
SWITCHING
OFF
BUCK-BOOST
SWITCHING
SWITCHING
SWITCHING
SWITCHING
BOOST
ON
Q2
OFF
Q3
SWITCHING
SWITCHING
Q4
ON
10
ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
