Boost switch-mode battery charger introduction

[MUSIC PLAYING] Now, I'd like to introduce a
variant of the buck charger which can allow you to charge
a higher voltage battery from a low voltage input. This is called
the boost charger. Similar to a buck charger,
a typical boost charger will have four FETs to control
charging and power path. The charger operates as buck
converter running in reverse, thereby generating a higher
output voltage at system. As before, the battery
FET is operated as an LDO to control the current going
into two cell battery stack. The EVM footprint
can be achieved with around 133
millimeters squared, for a solution rated to standard
USB at five volt, three amp. The two cell
battery architecture is used to drive loads requiring
higher voltage and peak currents, such as
motors or speakers. However, this architecture
also dictates the need for self-balancing
in order to maximize energy storage in the stack.

As with buck converters, the
efficiency of the solution can be scaled with cost. This graph shows the efficiency
of BQ25882, TI's boost charger implemented for standard
USB input and two cell output. This device achieves 93%
efficiency at one amp charging. The applications
enabled by this approach include IP cameras,
tablets, portable speakers, electronic point of sale
devices, and much more. The 2S battery
configuration really opens the door for a wide range
of different applications. The boost charger can
charge a two cell battery stack with up to two amps
from a dedicated adapter or a standard five
volt USB source. The circuit can be
implemented with a tiny 133 millimeters square PCB footprint
and can achieve around 93% efficiency.

This device offers a
simple charging solution for two cell designs that
can power higher loads..

As found on YouTube